A magnetic field dynamic compensation system and method suitable for underwater vehicles

Abstract

The present application relates to a kind of magnetic field dynamic compensation system and method suitable for underwater vehicle.The system of the present application includes at least 2 magnetic field intensity sensors, at least 2 magnetic field gradient sensors, data collector, a set of longitudinal coil L, a set of transverse coil A, a set of vertical coil V, a set of magnetic field compensation power supply, magnetic field dynamic compensation controller and display terminal.The present application is suitable for the magnetic field dynamic compensation system of underwater vehicle, can simultaneously carry out real-time compensation to the residual fixed magnetism of underwater vehicle, fixed magnetic field variation and induced magnetic field, and the magnetic field compensation precision is high, system is simplified, algorithm is simple, and adaptability is strong.

Description

Technical Field

[0001] This invention relates to the field of underwater vehicle demagnetization technology, and in particular to a device and its method for dynamically and in real-time compensating for the fixed magnetism and induced magnetism of an underwater vehicle using a shipborne magnetic field compensation system. Background Technology

[0002] The overall magnetic field of an underwater vehicle can be divided into two categories: fixed magnetic field and induced magnetic field. Traditionally, the fixed magnetic field is demagnetized through demagnetization, while the induced magnetic field is compensated in real time by an onboard magnetic field compensation system. Although the fixed magnetic field of an underwater vehicle can reach a certain level after demagnetization, it will still change during navigation due to various factors such as the Earth's magnetic field, seawater pressure, wind and waves, and equipment operation. Over time, the fixed magnetic field characteristics of the underwater vehicle will increase, causing the overall magnetic characteristics of the underwater vehicle to exceed control limits.

[0003] Dynamic magnetic field compensation technology refers to a technology that addresses the changing fixed magnetic field of an underwater vehicle during navigation, particularly the short-term reversible changes in the fixed magnetic field caused by the instantaneous pressure of seawater during descent. This is achieved by deploying a number of sensors at key locations within the underwater vehicle to measure the internal magnetic field, track these changes in real time, and optimize the current output of the demagnetizing winding to reduce the magnetic characteristic signal of the underwater vehicle. Dynamic magnetic field compensation technology can truly achieve "on-demand demagnetization," providing optimal compensation at the target depth and ensuring the long-term magnetic stealth performance of the underwater vehicle. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing shipborne magnetic field compensation systems for underwater vehicles, which can only compensate for induced magnetic fields. This invention proposes a simplified, algorithmic, and effective dynamic magnetic field compensation system for underwater vehicles.

[0005] This invention uses only one shipborne magnetic field compensation system hardware platform to perform real-time compensation for the induced magnetism of underwater vehicles, as well as real-time compensation for the fixed magnetism of underwater vehicles, with good control effect and applicability.

[0006] This invention proposes a dynamic magnetic field compensation system suitable for underwater vehicles, wherein the underwater vehicle has a conning tower or superstructure made of low-magnetic material. The dynamic magnetic field compensation system includes: a magnetic field strength sensor, a magnetic field gradient sensor, a data acquisition unit, a longitudinal coil L, a transverse coil A, a vertical coil V, a magnetic field compensation power supply, a dynamic magnetic field compensation controller, and a display terminal.

[0007] The magnetic field strength sensor is installed in the conning tower or superstructure of the underwater vehicle, located on the inner side of the underwater vehicle, and is used to measure the geomagnetic field parameters at the location of the underwater vehicle.

[0008] The magnetic field gradient sensor is installed in the conning tower or superstructure of the underwater vehicle, located on the inner side of the underwater vehicle, and is used to measure the magnetic field parameters of the underwater vehicle. The two types of sensors are grouped and distributed. They can be distributed on the top of the hull and in various parts around it.

[0009] The data acquisition unit collects magnetic field parameters from the magnetic field sensor and the magnetic field gradient sensor, and transmits the measurement data to the magnetic field dynamic compensation controller. Based on the acquired magnetic field parameters, the magnetic field dynamic compensation controller calculates magnetic field compensation currents to compensate for the longitudinal, lateral, and vertical magnetization components of the underwater vehicle.

[0010] The magnetic field compensation power supply provides corresponding magnetic field compensation current to the longitudinal coil L, the transverse coil A, and the vertical coil V.

[0011] The longitudinal coil L uses the magnetic field compensation current provided by the magnetic field compensation power supply to generate a magnetic field component that counteracts the longitudinal magnetization of the underwater vehicle.

[0012] The lateral coil A uses the magnetic field compensation current provided by the magnetic field compensation power supply to generate a magnetic field component that counteracts the lateral magnetization of the underwater vehicle.

[0013] The vertical coil V uses the magnetic field compensation current provided by the magnetic field compensation power supply to generate a magnetic field component that counteracts the vertical magnetization of the underwater vehicle.

[0014] The display terminal is used to receive and display the status information of the magnetic field compensation power supply and the magnetic field measurement information.

[0015] Furthermore, the magnetic field dynamic compensation controller calculates the magnetic field compensation current in the following manner:

[0016] (1) Based on the measured magnetic field gradient information, extract the change in magnetic field gradient and calculate the change in fixed magnetic field at a predetermined depth.

[0017] (2) Calculate the Earth's magnetic field components based on the measured magnetic field strength information;

[0018] (3) Calculate the induced magnetic field from the Earth's magnetic field obtained in step (2) based on the linear proportional relationship between the induced magnetic field and the Earth's magnetic field obtained in advance.

[0019] (4) Based on the pre-measured efficiencies of the longitudinal coil L, the transverse coil A and the vertical coil V, the currents of the longitudinal coil L, the transverse coil A and the vertical coil V are calculated from the pre-measured fixed magnetic field of the underwater vehicle, the change in the fixed magnetic field obtained in step (1) and the induced magnetic field obtained in step (3).

[0020] For each set of sensors at each measurement point, the following calculations are performed.

[0021] The change in a fixed magnetic field is calculated using the following method:

[0022] (1.1) The gradient change ΔH of the x component of the magnetic field in the x, y and z directions, measured by the first magnetic field gradient sensor (1). xx1 ΔH xy1 ΔH xz1 The magnetic moment ΔM of the underwater vehicle's ellipsoid in three directions is calculated using the following formula. x1 ΔM y1 ΔM z1 ;

[0023]

[0024] in:

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031] In the formula: x, y, and z are the coordinates of the magnetic field gradient sensor relative to the center point of the underwater vehicle, and g is the half focal length of the underwater vehicle ellipsoid.

[0032] (1.2) The gradient changes ΔH of the z component of the magnetic field in the x, y and z directions, as measured by the second magnetic field gradient sensor 2. zx2 ΔH zy2 ΔH zz2 The magnetic moment ΔM of the underwater vehicle's ellipsoid in three directions is calculated using the following formula. x2 ΔM y2 ΔM z2 ;

[0033]

[0034] in:

[0035]

[0036]

[0037]

[0038]

[0039] (1.3) Determine the three-directional magnetic moment ΔM of the underwater vehicle ellipsoid obtained in steps (1.1) and (1.2). x1 ΔM y1 ΔM z1 and ΔM x2 ΔM y2 ΔM z2 If the difference is less than a predetermined threshold, the magnetic field gradient sensor measurement is considered correct and valid. The magnetic moment ΔM is calculated by taking the average of the two values. x ΔM y and ΔM z ;

[0040] (4) Calculate the magnetic moment ΔM x ΔM y and ΔM z The change in the fixed magnetic field at a predetermined depth for an underwater vehicle can be calculated using the following formula.

[0041]

[0042]

[0043]

[0044] In the formula: Among them, the spacecraft is approximated as an ellipsoid. Let m be the semi-focal length of the ellipsoid, a and b be the semi-major and semi-minor axes of the ellipsoid, respectively, and m be the semi-focal length of the ellipsoid. x m y m z Let x, y, and z represent the magnetic moments in the three directions, respectively. Given the magnetic moments of the ellipsoid in the three directions, the three components of the magnetic field at any point in space can be calculated using the above formula.

[0045] Furthermore, the Earth's magnetic field is calculated using the following method:

[0046] (2.1) The three components of the magnetic field H obtained by magnetic field strength sensor 1 x1 H y1 H z1Based on the pre-measured linear proportional relationship between the induced magnetic field at the location of sensor 1 and the Earth's magnetic field, the three components H of the Earth's magnetic field are calculated. Dx1 H Dy1 H Dz1 The linear proportional relationship is obtained by simulating changes in the Earth's magnetic field using an external excitation magnetic field;

[0047] (2.2) The three components of the magnetic field H obtained by magnetic field strength sensor 2 x2 H y2 H z2 Based on the pre-measured linear proportional relationship between the induced magnetic field at the location of the magnetic field strength sensor 2 and the Earth's magnetic field, the three components H of the Earth's magnetic field are calculated. Dx2 H Dy2 H Dz2 ;

[0048] (2.3) Determine the three components H of the Earth's magnetic field calculated in steps (2.1) and (2.2). Dx1 H Dy1 H Dz1 and H Dx2 H Dy2 H Dz2 If the difference is less than a predetermined threshold, the magnetic field strength sensor measurement is considered correct and valid. The mean of both values ​​is used to calculate the geomagnetic field H. Dx H Dy H Dz .

[0049] Further, step (4) includes:

[0050] Suppose that there are K magnetic field measurement points in the underwater vehicle. Substitute the coordinates of different magnetic field measurement points into the formula in step (1) above to calculate the magnetic field component H at each measurement point. zK The relationship between the change in demagnetizing winding current and the magnetic field to be compensated can be expressed by the following formula:

[0051]

[0052] In the formula: Let ΔI represent the demagnetization winding efficiency of the longitudinal magnetic field z-component of the i-th X-direction winding at the j-th external measurement point, respectively. XQi The compensation current to be determined is given by the demagnetizing winding efficiency, which characterizes the magnetic field generated by a unit current in the demagnetizing winding at a certain external measurement point.

[0053] This system of equations is overdetermined. The least squares method is used to solve it, yielding ΔI. XQi The approximate solution serves as the adjustment amount for the longitudinal demagnetizing winding current. Similarly, by incorporating the transverse and vertical magnetic field components, the transverse and vertical winding currents can be obtained respectively.

[0054] On the other hand, the present invention provides a method for dynamic magnetic field compensation applicable to underwater vehicles, the method being used to perform dynamic magnetic field compensation on said underwater vehicle having a conning tower or superstructure made of low magnetic material.

[0055] The method includes:

[0056] The magnetic field compensation current is calculated using the following method:

[0057] (1) Based on the measured magnetic field gradient information, extract the change in magnetic field gradient and calculate the change in fixed magnetic field at a predetermined depth.

[0058] (2) Calculate the Earth's magnetic field components based on the measured magnetic field strength information;

[0059] (3) Calculate the induced magnetic field from the Earth's magnetic field obtained in step (2) based on the linear proportional relationship between the induced magnetic field and the Earth's magnetic field obtained in advance.

[0060] (4) Based on the pre-measured efficiencies of the longitudinal coil L, the transverse coil A and the vertical coil V, the currents of the longitudinal coil L, the transverse coil A and the vertical coil V are calculated from the pre-measured fixed magnetic field of the underwater vehicle, the change in the fixed magnetic field obtained in step (1) and the induced magnetic field obtained in step (3).

[0061] To cancel out the X, Y, and Z components of the vector sum of the magnetic field to be compensated (i.e., the fixed magnetic field, the change in the fixed magnetic field, and the induced magnetic field) to zero, the X, Y, and Z components generated by the currents in the longitudinal, transverse, and vertical coils are calculated using efficiency calculations to compensate for the magnetic field. The calculation process involves solving an overdetermined system of equations with more equations than variables, typically using the least squares method. After compensation, the magnetic field can only approach zero. The number of measurement points is greater than the number of overdetermined equations.

[0062] It should be noted that this invention is mainly applicable to underwater vehicles with a generally ellipsoidal structure and uses an ellipsoidal model for approximate calculations.

[0063] The magnetic field dynamic compensation system for underwater vehicles proposed in this invention has the following advantages:

[0064] (1) The magnetic field compensation accuracy is high, and it can simultaneously control the changes in the induced magnetism, residual fixed magnetism and fixed magnetic field of the underwater vehicle in real time.

[0065] (2) The algorithm is simple, has low computational overhead, and is easy to implement;

[0066] (3) Existing distributed magnetic field compensation systems can acquire dynamic magnetic field compensation capabilities by introducing this invention, which is highly adaptable and easy to upgrade. Attached Figure Description

[0067] Figure 1 This is a block diagram illustrating the composition principle of a dynamic magnetic field compensation system for underwater vehicles according to the present invention. Detailed Implementation

[0068] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0069] like Figure 1 As shown, the magnetic field dynamic compensation system for underwater vehicles of the present invention includes at least two magnetic field strength sensors, at least two magnetic field gradient sensors, a data acquisition unit, a set of longitudinal coils L, a set of transverse coils A, a set of vertical coils V, a set of magnetic field compensation power supply, a magnetic field dynamic compensation controller, and a display terminal.

[0070] The magnetic field strength sensor is installed in the conning tower or superstructure of the underwater vehicle, made of low magnetic material, on the upper inner side of the vehicle, and is used to measure the geomagnetic field parameters at the location of the underwater vehicle.

[0071] The magnetic field gradient sensor is installed in the conning tower or superstructure of an underwater vehicle made of low magnetic material, located on the upper inner side of the vehicle, and is used to measure the magnetic field parameters (gradient) of the underwater vehicle.

[0072] The data acquisition unit acquires the magnetic field parameters obtained by the magnetic field sensor and the magnetic field gradient sensor, and transmits the measurement data to the magnetic field dynamic compensation controller. The magnetic field dynamic compensation controller calculates the magnetic field compensation current based on the acquired magnetic field parameters to offset the magnetic field components of the longitudinal, lateral and vertical magnetization of the underwater vehicle.

[0073] The magnetic field compensation power supply provides corresponding magnetic field compensation current to the longitudinal coil L, the transverse coil A, and the vertical coil V.

[0074] The longitudinal coil L uses the magnetic field compensation current provided by the magnetic field compensation power supply to generate a magnetic field component that counteracts the longitudinal magnetization of the underwater vehicle.

[0075] The transverse coil A uses the magnetic field compensation current provided by the magnetic field compensation power supply to generate a magnetic field component that counteracts the transverse magnetization of the underwater vehicle.

[0076] The vertical coil V uses the magnetic field compensation current provided by the magnetic field compensation power supply to generate a magnetic field component that counteracts the vertical magnetization of the underwater vehicle.

[0077] The display terminal is used to receive and display the status information of the magnetic field compensation power supply and the magnetic field measurement information.

[0078] The magnetic field dynamic compensation system for underwater vehicles proposed in this invention calculates the magnetic field compensation current using the following method:

[0079] (1) Based on the measured magnetic field gradient information, extract the change in magnetic field gradient and calculate the change in fixed magnetic field at a predetermined depth.

[0080] (2) Calculate the Earth's magnetic field components based on the measured magnetic field strength information;

[0081] (3) Calculate the induced magnetic field from the Earth's magnetic field obtained in step (2) based on the linear proportional relationship between the induced magnetic field and the Earth's magnetic field obtained in advance.

[0082] (4) Based on the pre-measured efficiencies of the longitudinal coil L, the transverse coil A and the vertical coil V, the currents of the longitudinal coil L, the transverse coil A and the vertical coil V are calculated from the pre-measured fixed magnetic field of the underwater vehicle, the change in the fixed magnetic field obtained in step (1) and the induced magnetic field obtained in step (3).

[0083] The magnetic field dynamic compensation system for underwater vehicles proposed in this invention calculates the change in a fixed magnetic field using the following method:

[0084] (1) The gradient changes ΔH of the x component of the magnetic field in the x, y, and z directions, as measured by magnetic field gradient sensor 1. xx1 ΔH xy1 ΔH xz1 The magnetic moment ΔM of the underwater vehicle's ellipsoid in three directions is calculated using the following formula. x1 ΔM y1 ΔM z1 ;

[0085]

[0086] in:

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093] In the formula: x, y, and z are the coordinates of the magnetic field gradient sensor relative to the center point of the underwater vehicle, and g is the half focal length of the underwater vehicle ellipsoid.

[0094] (2) The gradient changes ΔH of the z component of the magnetic field in the x, y, and z directions, as measured by the magnetic field gradient sensor 2.zx2 ΔH zy2 ΔH zz2 The magnetic moment ΔM of the underwater vehicle's ellipsoid in three directions is calculated using the following formula. x2 ΔM y2 ΔM z2 ;

[0095]

[0096] in:

[0097]

[0098]

[0099]

[0100]

[0101] (3) Determine the three-directional magnetic moment ΔM of the underwater vehicle ellipsoid obtained in steps (1) and (2). x1 ΔM y1 ΔM z1 and ΔM x2 ΔM y2 ΔM z2 If the difference is less than a predetermined threshold, the magnetic field gradient sensor measurement is considered correct and valid. The magnetic moment ΔM is calculated by taking the average of the two values. x ΔM y and ΔM z ;

[0102] (4) Calculate the magnetic moment ΔM x ΔM y and ΔM z The change in the fixed magnetic field of an underwater vehicle at a predetermined depth is calculated based on the formula for the magnetic field of an ellipsoid.

[0103] The magnetic field dynamic compensation system for underwater vehicles proposed in this invention calculates the Earth's magnetic field using the following method:

[0104] (1) The three components of the magnetic field H measured by magnetic field strength sensor 1 x1 H y1 H z1 Based on the pre-measured linear proportional relationship between the induced magnetic field at the location of sensor 1 and the Earth's magnetic field, the three components H of the Earth's magnetic field are calculated. Dx1 H Dy1 H Dz1 ;

[0105] (2) The three components of the magnetic field H measured by magnetic field strength sensor 2 x2 Hy2 H z2 Based on the pre-measured linear proportional relationship between the induced magnetic field at the location of the magnetic field strength sensor 2 and the Earth's magnetic field, the three components H of the Earth's magnetic field are calculated. Dx2 H Dy2 H Dz2 ;

[0106] (3) Determine the three components of the Earth's magnetic field H obtained in steps (1) and (2). Dx1 H Dy1 H Dz1 and H Dx2 H Dy2 H Dz2 If the difference is less than a predetermined threshold, the magnetic field strength sensor measurement is considered correct and valid. The mean of both values ​​is used to calculate the geomagnetic field H. Dx H Dy H Dz .

[0107] The change in a fixed magnetic field is calculated using the following method:

[0108] (1.1) The gradient changes ΔH of the x-component of the magnetic field in the x, y, and z directions, as measured by magnetic field gradient sensor 1. xx1 ΔH xy1 ΔH xz1 The magnetic moment ΔM of the underwater vehicle's ellipsoid in three directions is calculated using the following formula. x1 ΔM y1 ΔM z1 ;

[0109]

[0110] in:

[0111]

[0112]

[0113]

[0114]

[0115]

[0116]

[0117] In the formula: x, y, and z are the coordinates of the magnetic field gradient sensor relative to the center point of the underwater vehicle, and g is the half focal length of the underwater vehicle ellipsoid.

[0118] (1.2) The gradient changes ΔH of the z component of the magnetic field in the x, y and z directions, as measured by the magnetic field gradient sensor 2. zx2 ΔH zy2 ΔH zz2 The magnetic moment ΔM of the underwater vehicle's ellipsoid in three directions is calculated using the following formula. x2 ΔM y2 ΔM z2 ;

[0119]

[0120] in:

[0121]

[0122]

[0123]

[0124]

[0125] (1.3) Determine the three-directional magnetic moment ΔM of the underwater vehicle ellipsoid obtained in steps (1.1) and (1.2). x1 ΔM y1 ΔM z1 and ΔM x2 ΔM y2 ΔM z2 If the difference is less than a predetermined threshold, the magnetic field gradient sensor measurement is considered correct and valid. The magnetic moment ΔM is calculated by taking the average of the two values. x ΔM y and ΔM z ;

[0126] (4) Calculate the magnetic moment ΔM x ΔM y and ΔM z The change in the fixed magnetic field at a predetermined depth for an underwater vehicle can be calculated using the following formula.

[0127]

[0128]

[0129]

[0130] In the formula: Among them, the spacecraft is approximated as an ellipsoid. Let m be the semi-focal length of the ellipsoid, a and b be the semi-major and semi-minor axes of the ellipsoid, respectively, and m be the semi-focal length of the ellipsoid. x m y mz Let x, y, and z represent the magnetic moments in the three directions, respectively. Given the magnetic moments of the ellipsoid in the three directions, the three components of the magnetic field at any point in space can be calculated using the above formula.

[0131] In order to cancel out the directional components of the vector sum of the three magnetic fields to be compensated (i.e., the fixed magnetic field, the change in the fixed magnetic field, and the induced magnetic field) to zero, the longitudinal, transverse, and vertical magnetic fields of the magnetic field to be compensated are compensated by the longitudinal coil L, the transverse coil A, and the vertical coil V, respectively.

[0132] Based on the pre-measured efficiencies of the longitudinal coil L, transverse coil A, and vertical coil V, the currents of the longitudinal coil L, transverse coil A, and vertical coil V are calculated using the pre-measured fixed magnetic field of the underwater vehicle, the change in the fixed magnetic field obtained in step (1), and the induced magnetic field obtained in step (3).

[0133] If there are K measurement points (set inside or around the aircraft), the relationship between the change in demagnetizing winding current and the magnetic field to be compensated can be expressed by the following formula:

[0134]

[0135] In the formula: Let ΔI represent the demagnetization winding efficiency of the longitudinal magnetic field z-component of the i-th X-direction winding at the j-th external measurement point, respectively. XQi The compensation current to be determined is [value]. The demagnetizing winding efficiency characterizes the magnetic field generated by a unit current in the demagnetizing winding at an external measuring point. It can be measured at a measuring station.

[0136] In this invention, the linear proportional relationship between the induced magnetic field and the Earth's magnetic field, the remaining fixed magnetic field of the underwater vehicle, and the coil efficiency are obtained through actual measurement, and the corresponding data are stored in the magnetic field dynamic compensation controller.

[0137] This invention can avoid the decrease in magnetic field control accuracy of underwater vehicles due to excessive magnetic field measurement errors. The predetermined threshold for magnetic moment calculation reflects the proportion of magnetic moment difference to the magnetic moment of the underwater vehicle, and a typical value can be set to 5%; the predetermined threshold for magnetic field calculation reflects the proportion of magnetic field difference to the background geomagnetic field, and a typical value can be set to 1%.

[0138] The magnetic field dynamic compensation system for underwater vehicles proposed in this invention can automatically switch to the traditional geomagnetic calculation mode when the magnetic field sensor fails. Based on the latitude and longitude information sent by the navigation system, the geomagnetic field parameters are determined according to the geomagnetic map. The induced magnetic field is calculated in combination with the heading and attitude of the underwater vehicle, and then the demagnetizing winding current is calculated. This can simultaneously take into account the functions of the traditional magnetic field compensation system.

[0139] This invention is not limited to the specific embodiments described above. Those skilled in the art can implement this invention using various other specific embodiments based on the disclosed content of the embodiments and accompanying drawings. Therefore, any design that adopts the design structure and concept of this invention and makes some simple changes or modifications falls within the protection scope of this invention.

Claims

1. A dynamic magnetic field compensation system for an underwater vehicle, the underwater vehicle having a conning tower or superstructure made of a low-magnetic material, characterized in that, The magnetic field dynamic compensation system includes: a magnetic field strength sensor, a magnetic field gradient sensor, a data acquisition unit, a longitudinal coil L, a transverse coil A, a vertical coil V, a magnetic field compensation power supply, a magnetic field dynamic compensation controller, and a display terminal. The magnetic field strength sensor is installed in the conning tower or superstructure of the underwater vehicle and is used to measure the geomagnetic field parameters at the location of the underwater vehicle. The magnetic field gradient sensor is installed in the conning tower or superstructure of the underwater vehicle and is used to measure the magnetic field parameters of the underwater vehicle. The data acquisition unit collects magnetic field parameters from the magnetic field sensor and the magnetic field gradient sensor, and transmits the measurement data to the magnetic field dynamic compensation controller. Based on the acquired magnetic field parameters, the magnetic field dynamic compensation controller calculates magnetic field compensation currents to compensate for the longitudinal, lateral, and vertical magnetization components of the underwater vehicle. The magnetic field compensation power supply provides corresponding magnetic field compensation current to the longitudinal coil L, the transverse coil A, and the vertical coil V. The longitudinal coil L uses the magnetic field compensation current provided by the magnetic field compensation power supply to generate a magnetic field component that counteracts the longitudinal magnetization of the underwater vehicle. The lateral coil A uses the magnetic field compensation current provided by the magnetic field compensation power supply to generate a magnetic field component that counteracts the lateral magnetization of the underwater vehicle. The vertical coil V uses the magnetic field compensation current provided by the magnetic field compensation power supply to generate a magnetic field component that counteracts the vertical magnetization of the underwater vehicle. The display terminal is used to receive and display the status information of the magnetic field compensation power supply and the magnetic field measurement information.

2. The magnetic field dynamic compensation system for underwater vehicles according to claim 1, characterized in that, The magnetic field dynamic compensation controller calculates the magnetic field compensation current using the following method: Step (1) Based on the measured magnetic field gradient information, extract the change in magnetic field gradient and calculate the change in fixed magnetic field at a predetermined depth. Step (2) Calculate the Earth's magnetic field components based on the measured magnetic field strength information; Step (3) Calculate the induced magnetic field from the Earth's magnetic field obtained in step (2) based on the linear proportional relationship between the induced magnetic field and the Earth's magnetic field obtained in advance. Step (4) Based on the pre-measured efficiencies of the longitudinal coil L, transverse coil A, and vertical coil V, the currents of the longitudinal coil L, transverse coil A, and vertical coil V are calculated from the pre-measured fixed magnetic field of the underwater vehicle, the change in the fixed magnetic field obtained in step (1), and the induced magnetic field obtained in step (3).

3. The magnetic field dynamic compensation system for underwater vehicles according to claim 2, characterized in that, The change in the fixed magnetic field of the aircraft is calculated using the following method: (1.1) The gradient change ΔH of the x component of the magnetic field in the x, y and z directions, measured by the first magnetic field gradient sensor (1). xx1 ΔH xy1 ΔH xz1 The magnetic moment ΔM of the underwater vehicle's ellipsoid in three directions is calculated using the following formula. x1 ΔM y1 ΔM z1 ; in: In the formula: x, y, and z are the coordinates of the magnetic field gradient sensor relative to the center point of the underwater vehicle, and g is the half focal length of the underwater vehicle's ellipsoid. (1.2) The gradient changes ΔH of the z component of the magnetic field in the x, y and z directions, as measured by the second magnetic field gradient sensor (2). zx2 ΔH zy2 ΔH zz2 The magnetic moment ΔM of the underwater vehicle's ellipsoid in three directions is calculated using the following formula. x2 ΔM y2 ΔM z2 ; in: (1.3) Determine the three-directional magnetic moment ΔM of the underwater vehicle ellipsoid obtained in steps (1.1) and (1.2). x1 ΔM y1 ΔM z1 and ΔM x2 ΔM y2 ΔM z2 If the difference is less than a predetermined threshold, the magnetic field gradient sensor measurement is considered correct and valid. The magnetic moment ΔM is calculated by taking the average of the two values. x ΔM y and ΔM z ; (4) Calculate the magnetic moment ΔM x ΔM y and ΔM z The change in the fixed magnetic field at a predetermined depth for an underwater vehicle can be calculated using the following formula. In the formula: Among them, the spacecraft is approximated as an ellipsoid. Let m be the semi-focal length of the ellipsoid, a and b be the semi-major and semi-minor axes of the ellipsoid, respectively, and m be the semi-focal length of the ellipsoid. x m y m z Let x, y, and z represent the magnetic moments in the three directions, respectively. Given the magnetic moments of the ellipsoid in the three directions, the three components of the magnetic field at any point in space can be calculated using the above formula.

4. The magnetic field dynamic compensation system for underwater vehicles according to claim 2 or 3, characterized in that, The Earth's magnetic field is calculated using the following method: (2.1) The three components of the magnetic field H measured by the first magnetic field strength sensor (1) x1 H y1 H z1 And based on the linear proportional relationship between the induced magnetic field at the location of the first magnetic field strength sensor (1) and the Earth's magnetic field, the three components H of the Earth's magnetic field are calculated. Dx1 H Dy1 H Dz1 The linear proportional relationship is obtained by simulating changes in the Earth's magnetic field using an external excitation magnetic field; (2.2) The three components of the magnetic field H measured by the second magnetic field strength sensor (2) x2 H y2 H z2 And based on the linear proportional relationship between the induced magnetic field at the location of the second magnetic field strength sensor (2) and the Earth's magnetic field, the three components H of the Earth's magnetic field are calculated. Dx2 H Dy2 H Dz2 ; (2.3) Determine the three components H of the Earth's magnetic field calculated in steps (2.1) and (2.2). Dx1 H Dy1 H Dz1 and H Dx2 H Dy2 H Dz2 If the difference is less than a predetermined threshold, the magnetic field strength sensor measurement is considered correct and valid. The mean of both values ​​is used to calculate the geomagnetic field H. Dx H Dy H Dz .

5. The magnetic field dynamic compensation system for underwater vehicles according to claim 3, characterized in that, Step (4) includes: Suppose there are K magnetic field measurement points set up in or around the underwater vehicle. Substitute the coordinates of different magnetic field measurement points into the formula in step (1) above to calculate the magnetic field component H at each measurement point. zK The relationship between the change in demagnetizing winding current and the magnetic field to be compensated can be expressed by the following formula: In the formula: Let ΔI represent the demagnetization winding efficiency of the longitudinal magnetic field z-component of the i-th X-direction winding at the j-th external measurement point, respectively. XQi The compensation current to be determined is given by the demagnetizing winding efficiency, which characterizes the magnetic field generated by a unit current in the demagnetizing winding at an external measurement point. This system of equations is overdetermined. The least squares method is used to solve it, yielding ΔI. XQi The approximate solution, as the adjustment amount of the longitudinal demagnetizing winding current, can be used to obtain the transverse and vertical winding currents in the same way.

6. A method for dynamic magnetic field compensation suitable for underwater vehicles, characterized in that, The method is used for dynamic magnetic field compensation of an underwater vehicle as described in claim 1, which has a conning tower or superstructure made of a low-magnetic material. The method includes: The magnetic field compensation current is calculated as follows: (1) Based on the measured magnetic field gradient information, extract the change in magnetic field gradient and calculate the change in fixed magnetic field at a predetermined depth. (2) Calculate the Earth's magnetic field components based on the measured magnetic field strength information; (3) Calculate the induced magnetic field from the Earth's magnetic field obtained in step (2) based on the linear proportional relationship between the induced magnetic field and the Earth's magnetic field obtained in advance. (4) Based on the pre-measured efficiencies of the longitudinal coil L, the transverse coil A and the vertical coil V, the currents of the longitudinal coil L, the transverse coil A and the vertical coil V are calculated from the pre-measured fixed magnetic field of the underwater vehicle, the change in the fixed magnetic field obtained in step (1) and the induced magnetic field obtained in step (3).

7. The method for dynamic magnetic field compensation for underwater vehicles according to claim 6, characterized in that, The change in a fixed magnetic field is calculated using the following method: (1.1) The gradient changes ΔH of the x component of the magnetic field in the x, y, and z directions, as measured by magnetic field gradient sensor 1. xx1 ΔH xy1 ΔH xz1 The magnetic moment ΔM of the underwater vehicle's ellipsoid in three directions is calculated using the following formula. x1 ΔM y1 ΔM z1 ; in: In the formula: x, y, and z are the coordinates of the magnetic field gradient sensor relative to the center point of the underwater vehicle, and g is the half focal length of the underwater vehicle's ellipsoid. (1.2) The gradient changes ΔH of the z component of the magnetic field in the x, y and z directions, as measured by the magnetic field gradient sensor 2. zx2 ΔH zy2 ΔH zz2 The magnetic moment ΔM of the underwater vehicle's ellipsoid in three directions is calculated using the following formula. x2 ΔM y2 ΔM z2 ; in: (1.3) Determine the three-directional magnetic moment ΔM of the underwater vehicle ellipsoid obtained in steps (1.1) and (1.2). x1 ΔM y1 ΔM z1 and ΔM x2 ΔM y2 ΔM z2 If the difference is less than a predetermined threshold, the magnetic field gradient sensor measurement is considered correct and valid. The magnetic moment ΔM is calculated by taking the average of the two values. x ΔM y and ΔM z ; (4) Calculate the magnetic moment ΔM x ΔM y and ΔM z The change in the fixed magnetic field at a predetermined depth for an underwater vehicle can be calculated using the following formula. In the formula: Among them, the spacecraft is approximated as an ellipsoid. Let m be the semi-focal length of the ellipsoid, a and b be the semi-major and semi-minor axes of the ellipsoid, respectively, and m be the semi-focal length of the ellipsoid. x m y m z Let x, y, and z represent the magnetic moments in the three directions, respectively. Given the magnetic moments of the ellipsoid in the three directions, the three components of the magnetic field at any point in space can be calculated using the above formula.

8. The method for dynamic magnetic field compensation for underwater vehicles according to claim 6, characterized in that, The Earth's magnetic field is calculated using the following method: (2.1) The three components of the magnetic field H obtained by magnetic field strength sensor 1 x1 H y1 H z1 Based on the pre-measured linear proportional relationship between the induced magnetic field at the location of magnetic field sensor 1 and the Earth's magnetic field, the three components H of the Earth's magnetic field are calculated. Dx1 H Dy1 H Dz1 The linear proportional relationship is obtained by simulating changes in the Earth's magnetic field using an external excitation magnetic field; (2.2) The three components of the magnetic field H obtained by magnetic field strength sensor 2 x2 H y2 H z2 Based on the pre-measured linear proportional relationship between the induced magnetic field at the location of the magnetic field strength sensor 2 and the Earth's magnetic field, the three components H of the Earth's magnetic field are calculated. Dx2 H Dy2 H Dz2 ; (2.3) Determine the three components H of the Earth's magnetic field calculated in steps (2.1) and (2.2). Dx1 H Dy1 H Dz1 and H Dx2 H Dy2 H Dz2 If the difference is less than a predetermined threshold, the magnetic field strength sensor measurement is considered correct and valid. The mean of both values ​​is used to calculate the geomagnetic field H. Dx H Dy H Dz .

9. The method for dynamic magnetic field compensation for underwater vehicles according to claim 6, characterized in that, Step (4) includes: Suppose there are K magnetic field measurement points set up in or around the underwater vehicle. Substitute the coordinates of different magnetic field measurement points into the formula in step (1) above to calculate the magnetic field component H at each measurement point. zK The relationship between the change in demagnetizing winding current and the magnetic field to be compensated can be expressed by the following formula: In the formula: Let ΔI represent the demagnetization winding efficiency of the longitudinal magnetic field z-component of the i-th X-direction winding at the j-th external measurement point, respectively. XQi The compensation current to be determined is given by the demagnetizing winding efficiency, which characterizes the magnetic field generated by a unit current in the demagnetizing winding at an external measurement point. This system of equations is overdetermined. The least squares method is used to solve it, yielding ΔI. XQi The approximate solution, as the adjustment amount of the longitudinal demagnetizing winding current, can be used to obtain the transverse and vertical winding currents in the same way.

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