CN112285787B - System and method for detecting extremely low frequency magnetic field of underwater target from air - Google Patents

System and method for detecting extremely low frequency magnetic field of underwater target from air Download PDF

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CN112285787B
CN112285787B CN202011163619.6A CN202011163619A CN112285787B CN 112285787 B CN112285787 B CN 112285787B CN 202011163619 A CN202011163619 A CN 202011163619A CN 112285787 B CN112285787 B CN 112285787B
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underwater vehicle
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CN112285787A (en
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张宁
常明
程锦房
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Naval University of Engineering PLA
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Abstract

The invention provides a system and a method for detecting an extremely-low frequency magnetic field of an underwater target from air, wherein the system comprises a magnetic field sensor, a signal conditioning circuit and a data acquisition module; the magnetic field sensor is connected with the signal conditioning circuit, the signal conditioning circuit is connected with the data acquisition module, and the data acquisition module is connected with an external computer; the magnetic field sensor is used for collecting magnetic field signals and transmitting the magnetic field signals to the signal conditioning circuit; the signal conditioning circuit comprises an amplifying circuit and a filtering circuit, and the signal conditioning circuit is used for processing the magnetic field signal and transmitting the processed magnetic field signal to the data acquisition module and the computer. The system and the method for detecting the extremely low frequency magnetic field of the underwater target from the air realize effective and accurate detection of the extremely low frequency magnetic field of the underwater vehicle in the air, have wide application range, and can be applied to fixed platforms at seaside, aircrafts and the like.

Description

System and method for detecting extremely low frequency magnetic field of underwater target from air
Technical Field
The invention relates to the field of magnetic field detection of underwater vehicles, in particular to a system and a method for detecting an extremely low frequency magnetic field of an underwater target from air.
Background
When the underwater vehicle navigates, on one hand, a hull generates corrosion current in surrounding seawater, a cathode protection system adopted for preventing the hull from corrosion also generates corrosion-resistant current, and the periodic change of the resistance of a propeller-main shaft-hull loop generates periodic current for corrosion and corrosion-resistant current modulation, and the current generates an extremely low frequency magnetic field with the fundamental frequency of about 1-7 Hz. On the other hand, a rotating magnetic field formed by the presence of nonuniform magnetization or remanence of components such as the main shaft and the propeller is also a very low frequency magnetic field.
Magnetic anomaly detection is the most mature magnetic detection means at present, and the application of the magnetic anomaly detection is generally divided into three aspects, namely, mine magnetic fuzes, underwater magnetic target monitoring such as electromagnetic buoys and underwater monitoring nets, and aviation magnetic detection. The extremely low frequency magnetic field of the underwater vehicle can be used as a signal source for detecting the underwater vehicle. When the magnetic probe is used for magnetic detection of an aviation airplane, high-speed maneuvering detection can be performed on a large-area sea area, and the search efficiency is very high. However, degaussing techniques and degaussing techniques are continuously developed, and the signal source of the target becomes weaker. Therefore, there is a need for an improvement to the existing magnetic anomaly latency detection method to improve the latency detection capability.
Disclosure of Invention
In order to solve the above problems, the present invention provides a system and a method for detecting a very low frequency magnetic field of an underwater target from air.
A detection system for an extremely low frequency magnetic field of an underwater vehicle in the air comprises a magnetic field sensor, a signal conditioning circuit and a data acquisition module; the magnetic field sensor is connected with the signal conditioning circuit, the signal conditioning circuit is connected with the data acquisition module, and the data acquisition module is connected with an external computer;
the magnetic field sensor is used for collecting magnetic field signals and transmitting the magnetic field signals to the signal conditioning circuit; the signal conditioning circuit comprises an amplifying circuit and a filtering circuit, and the signal conditioning circuit is used for processing the magnetic field signal and transmitting the processed magnetic field signal to the data acquisition module and the computer.
In some embodiments, an instrumentation amplifier AD624 is adopted in the amplifying circuit; the magnetic field sensor adopts a three-axis fluxgate sensor Mag-13 or an inductive magnetic field sensor LEMI-120; the data acquisition module adopts an NI USB-6216 acquisition card.
In some embodiments, the filter circuit is a band-pass filter formed by connecting a second-order high-pass active filter and a fourth-order low-pass active filter in series.
In some embodiments, the filtering circuit is an adaptive filter based on the LMS adaptive algorithm.
The invention also provides a method for detecting the air middle-pole low-frequency magnetic field of the underwater vehicle, which adopts the detection system of the air middle-pole low-frequency magnetic field of the underwater vehicle and comprises the following steps:
s1, establishing an extremely low frequency magnetic field model and a magnetic interference compensation model of an underwater vehicle in the air in computer software;
s2, collecting magnetic field signals through a magnetic field sensor, and transmitting the magnetic field signals to a signal conditioning circuit;
s3, amplifying the magnetic field signal through a signal conditioning circuit, filtering out part of interference signals in the magnetic field signal, and transmitting the processed magnetic field signal to a data acquisition module and a computer;
and S4, further processing the data of the data acquisition module through the underwater vehicle in-air extremely low-frequency magnetic field model and the magnetic interference compensation model to calculate the underwater vehicle in-air extremely low-frequency magnetic field.
In some embodiments, in step S1, the step of modeling the magnetic field of the underwater vehicle at the extremely low frequency in the air comprises: the method comprises the steps of taking a horizontal electric dipole and a vertical electric dipole as equivalent sources of a low-frequency magnetic field generated by the underwater vehicle, respectively modeling the low-frequency magnetic field generated by the horizontal electric dipole and the vertical electric dipole in an air layer, modeling the low-frequency magnetic field generated by the rotation of a magnetic dipole, and combining the three to serve as a low-frequency magnetic field model of the underwater vehicle in the air.
Compared with the prior art, the system and the method for detecting the extremely low frequency magnetic field of the underwater target from the air, provided by the invention, realize the effective and accurate detection of the extremely low frequency magnetic field of the underwater vehicle in the air, have wide application range, and can be applied to fixed platforms at sea, aircrafts and the like.
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Fig. 1 is a schematic diagram of an underwater vehicle when detecting with a detection system of a very low frequency magnetic field in the air.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without inventive step, are within the scope of protection of the invention.
Unless otherwise defined, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs.
The invention provides a detection system for a very low-frequency magnetic field of an underwater vehicle in the air, which comprises a magnetic field sensor, a signal conditioning circuit and a data acquisition module, wherein the signal conditioning circuit is connected with the magnetic field sensor; the magnetic field sensor is connected with the signal conditioning circuit, the signal conditioning circuit is connected with the data acquisition module, and the data acquisition module is connected with an external computer; the magnetic field sensor is used for collecting magnetic field signals and transmitting the magnetic field signals to the signal conditioning circuit; the signal conditioning circuit comprises an amplifying circuit and a filter circuit, and the signal conditioning circuit is used for processing the magnetic field signal and then transmitting the magnetic field signal to the data acquisition module and the computer.
In a specific embodiment, an instrumentation amplifier AD624 is adopted in the amplifying circuit; the magnetic field sensor adopts a three-axis fluxgate sensor Mag-13 or an inductive magnetic field sensor LEMI-120; the data acquisition module adopts an NI USB-6216 acquisition card. The filter circuit can adopt a band-pass filter formed by connecting a second-order high-pass active filter and a fourth-order low-pass active filter in series.
Preferably, the filter circuit employs an adaptive filter based on an LMS adaptive algorithm. The LMS adaptive algorithm has the advantages that under the condition that reference noise is not known in advance, a time delay form of a measurement signal can be used as a reference signal, parameters can be continuously adjusted, the requirement on initial parameters is low, an embedded system is easy to realize, the instantaneity is high, broadband noise can be effectively inhibited under the condition of low signal-to-noise ratio, and the line spectrum of a target extremely-low frequency magnetic field signal is enhanced.
The invention also provides a method for detecting the air middle-pole low-frequency magnetic field of the underwater vehicle, which adopts the detection system of the air middle-pole low-frequency magnetic field of the underwater vehicle and comprises the following steps:
s1, establishing an extremely low frequency magnetic field model and a magnetic interference compensation model of an underwater vehicle in the air in computer software;
s2, collecting magnetic field signals through a magnetic field sensor, and transmitting the magnetic field signals to a signal conditioning circuit;
s3, amplifying the magnetic field signal through a signal conditioning circuit, filtering out part of interference signals in the magnetic field signal, and transmitting the processed magnetic field signal to a data acquisition module and a computer;
and S4, further processing the data of the data acquisition module through the underwater vehicle in-air extremely low-frequency magnetic field model and the magnetic interference compensation model to calculate the underwater vehicle in-air extremely low-frequency magnetic field.
Further, in step S1, the step of establishing a model of the extremely low frequency magnetic field of the underwater vehicle in the air includes: the method comprises the steps of taking a horizontal electric dipole and a vertical electric dipole as equivalent sources of a very low frequency magnetic field generated by the underwater vehicle, respectively modeling the very low frequency magnetic field generated by the horizontal electric dipole and the vertical electric dipole in an air layer, modeling the very low frequency magnetic field generated by the rotation of a magnetic dipole, and combining the three to serve as a very low frequency magnetic field model of the underwater vehicle in the air.
In one embodiment, the specific process of modeling is as follows:
when the underwater vehicle is sailing, on the one hand, the hull generates corrosion currents in the surrounding sea water, the cathodic protection system used to prevent hull corrosion also generates corrosion protection currents, and the periodic variation of the resistance of the propeller-main shaft-hull circuit generates periodic currents that generate a very low frequency magnetic field, in addition to the corrosion and corrosion protection currents that are modulated by the current. On the other hand, a rotating magnetic field formed by the presence of nonuniform magnetization or remanence of components such as the main shaft and the propeller is also a very low frequency magnetic field. Thus, the present invention models the current associated with corrosion of an underwater vehicle.
The alternating current formed after the corrosion-related current is modulated by the main shaft generally has two equivalent methods, namely an electric dipole model and a current section model. The current segment describes the current IL between the propeller and the anode of the cathodic protection system (I is the time-harmonic current intensity and L is the length of the current segment). When L is smaller, the current segment model is simplified into an electric dipole model. Experience has shown that when measuring distances greater than twice the length of the current segments, the current segments can be equated with an electrical dipole and the calculations are relatively simple. Therefore, the invention adopts an electric dipole model and models the extremely-low frequency magnetic fields generated by the horizontal electric dipole and the vertical electric dipole in the air layer respectively.
From the basic theory of electromagnetic fields, it is known that a time-varying current necessarily generates a time-varying magnetic field. A horizontal electric dipole or a vertical electric dipole is used as an equivalent source of an underwater vehicle low-frequency magnetic field generation model, and a schematic diagram of the underwater vehicle low-frequency magnetic field generation model under a shallow sea condition is shown in FIG. 1. The positive direction of the X axis corresponds to the direction of a boat bow of the underwater vehicle, the Y axis refers to the direction of a starboard, and the Z axis is vertically downward.
In fig. 1, the harmonic horizontal electric dipole and the vertical electric dipole are considered in the three-layer model composed of medium 0, medium 1, and medium 2. In practice, these three models correspond to air, seawater and seabed, respectively, and the electric dipoles are located in the seawater layer, so as to obtain a Maxwell equation set in a time-harmonic form:
Figure GDA0002822610610000041
wherein: j. the design is a square s Is the current density of the electric dipole; h i And B i Magnetic field intensity vector and magnetic induction intensity vector; e i And D i Respectively representing an electric field strength vector and an electric displacement vector; assuming that all three media are isotropic linear homogeneous media, σ i ，μ i ，ε i I =0,1,2 indicates the field number, respectively, for the electrical conductivity, the magnetic permeability and the dielectric constant.
Introduction of vector magnetic potential A, scalar potential phi and Lorentz specification
Figure GDA0002822610610000051
The helmholtz equation for vector magnetic potential can be derived from equations (1) and (2):
Figure GDA0002822610610000052
wherein k is a propagation constant, and k 2 ＝-jωμσ+ω 2 με。
The method for establishing the horizontal electric dipole model comprises the following steps:
in FIG. 1The coordinate of the horizontal electric dipole is (x) 0 ，0，z 0 ) The vector magnetic potential in the sea water layer is generated by a primary source and a secondary source, which can be expressed as A 1 ＝A 1p +A 1s Wherein A is 1p And A 1s Vector magnetic potential generated by primary source and secondary source, vector magnetic potential A of air layer and seabed layer 0 And A 2 Is generated by a secondary source, which can be denoted as A 0s And A 2s . The vector magnetic potential generated by the primary source of the horizontal electric dipole only has a component in the X direction, and the vector magnetic potential generated by the secondary source has two components in the X direction and the Z direction. Starting from a Sommerfeld basic formula, vector magnetic potential expressions of all field regions are obtained first, and then all magnetic fields are solved by utilizing electromagnetic field boundary conditions.
For medium 1, the vector magnetic bits can be expressed as:
Figure GDA0002822610610000053
and A is 0 、A 1s And A 2 All satisfy the homogeneous Helmholtz equation
Figure GDA0002822610610000054
The general solution can be expressed as:
Figure GDA0002822610610000055
wherein, i =0,2,
Figure GDA0002822610610000056
φ＝arctan(y/(x-x 0 ))，
Figure GDA0002822610610000057
J m (ρ ξ) is an m-th order Bessel function of the first kind. Also known from the Euler equation, e jmφ Phi + jsinum phi, while in the coordinate system (rho, phi, z) there is a (rho, phi, z) = a (rho, -phi, z), so e is obtained jmφ = cosm phi. Combining equation (4) and equation (5), one can obtain:
Figure GDA0002822610610000061
from the infinite boundary condition: when z approaches plus or minus infinity, A 0 And A 2 Should be of limited value. Then there is c 0 (ξ,m)＝0，d 0 (ξ,m)＝0，a 2 (ξ,m)＝0，b 2 (xi, m) =0, then A in formula (6) 0 And A 2 Can be written as:
Figure GDA0002822610610000062
the electromagnetic field air-seawater boundary conditions are as follows:
Figure GDA0002822610610000063
the electromagnetic field seawater-seabed boundary conditions are as follows:
Figure GDA0002822610610000064
the parameters of the vector magnetic potential are solved using the boundary conditions.
The method comprises the following steps: using a third equation in the boundary conditions [ A ] 1x -A 0x ] z＝0 =0 and [ A 2x -A 1x ] z＝d ＝0。
First, using [ A ] 1x -A 0x ] z＝0 =0, then there is,
Figure GDA0002822610610000071
the two equations are equal, and due to the existence of Bessel function, the equation a is combined with the electromagnetic field uniqueness theorem 0 (ξ,m)，a 1 (xi, m) and c 1 M in (xi, m) can only take 0, formula(10) It can be written as,
Figure GDA0002822610610000072
a parametric equation is obtained for the measured values,
Figure GDA0002822610610000073
then, using [ A 2x -A 1x ] z＝d =0, then there is,
Figure GDA0002822610610000074
the above two equations are equal, and the same as the derivation equations (11) and (12) indicates that c 2 (ξ,m)，a 1 (xi, m) and c 1 In (xi, m), m can only take 0, and the formula (13) can be written as,
Figure GDA0002822610610000075
then a parametric equation can be obtained that,
Figure GDA0002822610610000076
step two, utilizing a fourth equation in the boundary condition
Figure GDA0002822610610000081
And
Figure GDA0002822610610000082
first of all utilize
Figure GDA0002822610610000083
To deduce, there are,
Figure GDA0002822610610000084
the two equations are equal, and a parameter equation can be obtained by combining the uniqueness theorem of the electromagnetic field,
Figure GDA0002822610610000085
secondly, then, get the second
Figure GDA0002822610610000086
The derivation is carried out,
Figure GDA0002822610610000087
the two formulas are equal, and a parameter equation can be obtained in the same way,
Figure GDA0002822610610000088
the equations (12), (15), (17) and (19) are combined to obtain the following equation system, and a can be solved 0 (ξ,0)，a 1 (ξ,0)， c 1 (xi, 0) and c 2 (ξ,0)。
Figure GDA0002822610610000089
Step three: using the first equation in the boundary conditions
Figure GDA0002822610610000091
And
Figure GDA0002822610610000092
first, utilize
Figure GDA0002822610610000093
To derive.
For
Figure GDA0002822610610000094
Wherein:
Figure GDA0002822610610000095
it is possible to write out,
Figure GDA0002822610610000096
and is further provided with
Figure GDA0002822610610000097
Wherein the content of the first and second substances,
Figure GDA0002822610610000098
it is possible to write out,
Figure GDA0002822610610000099
combinations (23) and (24) of
Figure GDA0002822610610000101
A parametric equation can be obtained that,
Figure GDA0002822610610000102
the formula contains Bessel function, and combines with electromagnetic field uniqueness theorem, thereby obtaining b 0 (ξ,m)、 b 1 (xi, m) and d 1 In (xi, m), m can only take 1, so the parameter equation (25) can be simplified,
Figure GDA0002822610610000103
secondly, utilize
Figure GDA0002822610610000104
To derive.
Figure GDA0002822610610000105
Wherein:
Figure GDA0002822610610000106
then there is
Figure GDA0002822610610000107
Herein, the formula (22) was derived
Figure GDA0002822610610000108
The method comprises the following steps of (1),
Figure GDA0002822610610000111
is formed by combining a compound of formula (28) and a compound of formula (29)
Figure GDA0002822610610000112
Can derive b 1 (ξ,m)、d 1 (xi, m) and d 2 M in xi, m can only be 1, and a parameter equation is provided by combining the electromagnetic field uniqueness theorem,
Figure GDA0002822610610000113
step four: using a second equation in the boundary conditions
Figure GDA0002822610610000114
And
Figure GDA0002822610610000115
according to the derivation, the simplified vector magnetic potential equation is formed by,
Figure GDA0002822610610000116
first, at
Figure GDA0002822610610000117
In the formula (I), the following expression is shown,
Figure GDA0002822610610000121
combining with the uniqueness theorem of the electromagnetic field to obtain a parameter equation,
Figure GDA0002822610610000122
secondly, in
Figure GDA0002822610610000123
In the formula (I), the following expression is shown,
Figure GDA0002822610610000124
combining the uniqueness theorem of the electromagnetic field to obtain a parameter equation:
Figure GDA0002822610610000125
synthesizing the third and fourth Chinese formulas (26), (30), (34) and (35) to obtain a parameter equation set,
Figure GDA0002822610610000126
in conjunction with equations (20) and (36), the eight parameters of the vector magnetic potential can be solved. Therefore, the vector magnetic potential in the air can be obtained as,
Figure GDA0002822610610000131
wherein:
Figure GDA0002822610610000132
b 0 (ξ,1)＝b 1 (ξ,1)+d 1 (ξ,1)，
Figure GDA0002822610610000133
Figure GDA0002822610610000134
Figure GDA0002822610610000135
Figure GDA0002822610610000136
Figure GDA0002822610610000137
Figure GDA0002822610610000138
Figure GDA0002822610610000139
Figure GDA00028226106100001310
and then in formula (2)
Figure GDA00028226106100001311
The magnetic field of the horizontal electric dipole in the air can be respectively obtained,
Figure GDA0002822610610000141
the method for establishing the vertical electric dipole model comprises the following steps:
the magnetic field generated by vertical electric dipole with same strength in air layer is less than that generated by horizontal electric dipole, and the vertical electric dipole only has vector magnetic potential in vertical direction in each horizontal layered space [84] Thus A is 0 、 A 1 And A 2 Can be expressed as:
Figure GDA0002822610610000142
according to the Euler formula, e jmφ Phi + jsinum phi, while in the coordinate system (rho, phi, z) there is a (rho, phi, z) = a (rho, -phi, z), so e is obtained jmφ = cosm phi. From the infinity boundary condition: when z approaches plus or minus infinity, A 0 And A 2 Is of limited value. Then there is d 0 (ξ, m) =0 and b 2 (ξ, m) =0, and equation (39) can be simplified as follows:
Figure GDA0002822610610000143
Figure GDA0002822610610000151
since the vector magnetic bit has only the z-component, the electromagnetic field boundary conditions can be simplified as follows.
Air-seawater boundary conditions:
Figure GDA0002822610610000152
sea water-sea bed boundary conditions:
Figure GDA0002822610610000153
the method comprises the following steps: using a second equation in the boundary condition
Figure GDA0002822610610000154
And
Figure GDA0002822610610000155
the system of equations can be found:
Figure GDA0002822610610000156
b in the formula (43) by combining the electromagnetic field uniqueness theorem due to the Bessel existence 0 (ξ,m)、b 1 (ξ,m)、 d 1 (xi, m) and d 2 M in (xi, m) can only be 0, so that the process can be simplified to
Figure GDA0002822610610000157
Further, equation (40) can be written as,
Figure GDA0002822610610000161
step two: using the first equation of the boundary conditions
Figure GDA0002822610610000162
And
Figure GDA0002822610610000163
then there is a change in the number of,
Figure GDA0002822610610000164
by
Figure GDA0002822610610000165
And
Figure GDA0002822610610000166
a simplified parametric equation can be obtained,
Figure GDA0002822610610000167
summary parametric equations (44) and (47), having
Figure GDA0002822610610000168
Solving the equation system can obtain four parameters of the vector magnetic potential, therefore, the vector magnetic potential in the air can be obtained,
Figure GDA0002822610610000171
wherein:
Figure GDA0002822610610000172
Figure GDA0002822610610000173
Figure GDA0002822610610000174
Figure GDA0002822610610000175
Figure GDA0002822610610000176
Figure GDA0002822610610000177
by
Figure GDA0002822610610000178
The magnetic field of the vertical electric dipole in the air can be solved,
Figure GDA0002822610610000179
the method for establishing the extremely-low-frequency magnetic field model generated by the rotation of the magnetic dipoles comprises the following steps:
the inhomogeneous magnetization of the shafting of the underwater vehicle and the residual magnetism of the propeller can be equivalent to a uniform magnetic dipole at a longer distance. Assuming that the initial position of the magnetic dipole is the origin and on the axis of the main shaft, the X axis points to the ship bow direction, the Y axis is the starboard direction, and the Z axis is vertically downward. Magnetic moment M = M x ·e x +m y ·e y +m z ·e z In which e is x 、e y And e z Unit vectors of X, Y, Z axes, respectively, m x 、m y And m z The components of the magnetic dipole in the X, Y, and Z axes, respectively. The magnetic dipole makes uniform rotation motion around the X axis at an angular velocity omega.
The total magnetic moment of the magnetic dipole at time t is M '= M' x ·e x +m' y ·e y +m' z ·e z The magnetic moment components in each direction are respectively,
Figure GDA0002822610610000181
then for any point in space (x, y, z), the magnetic field distribution of the magnetic dipole at the origin at time t is
Figure GDA0002822610610000182
Wherein mu 0 The magnetic permeability is vacuum magnetic permeability, r is the vector diameter of a magnetic dipole pointing measuring point, and r = x.e x +y·e y +z·e z 。
Writing formula (52) in three-component form, having
Figure GDA0002822610610000183
Wherein the content of the first and second substances,
Figure GDA0002822610610000184
is the distance from the center of the magnetic dipole to the measurement point.
Due to the fact that the diameter of a main shaft and a propeller of the underwater vehicle is large, the center of an equivalent magnetic dipole deviates from the axis of the main shaft due to uneven magnetization, and the center of the equivalent magnetic dipole equivalently moves around a circle, and therefore the formula (53) can be modified. The connecting center of the propeller and the shaft is taken as an original point, and the distance between the central position of the residual magnetic moment of the shafting and the original point R and the negative direction included angle of the Y shaft are assumed to be
Figure GDA0002822610610000185
Then the magnetic dipole initial position x 0 ＝0，
Figure GDA0002822610610000186
Figure GDA0002822610610000187
The real-time position of the magnetic dipole can be written,
Figure GDA0002822610610000188
the magnetic field generated by the rotation of the magnetic dipole can be written,
Figure GDA0002822610610000189
wherein the content of the first and second substances,
Figure GDA00028226106100001810
in addition, in step S1, the specific steps of establishing the magnetic interference compensation model are as follows:
firstly, respectively establishing a residual magnetic model, an induction magnetic field model and an eddy magnetic field model of a background magnetic field, and combining the residual magnetic model, the induction magnetic field model and the eddy magnetic field model to be used as a total magnetic interference compensation model.
Specifically, in step S1, the step of establishing the residual magnetism model includes:
the remanence is expressed as: h p ＝{p 1 p 2 p 3 }
Then the projection in the direction of the geomagnetic vector at the measurement point is:
Figure GDA0002822610610000191
wherein u i ＝cosθ i Direction cosine of the geomagnetic vector;
the step of establishing the induced magnetic field model comprises the following steps:
the vector of the induced magnetic field at the measurement point is represented as:
Figure GDA0002822610610000192
the projection in the direction of the geomagnetic vector is:
Figure GDA0002822610610000193
wherein:
Figure GDA0002822610610000194
time of flight
a 11 ＝(i 11 -i 33 )B
a 22 ＝(i 22 -i 33 )B
Let a 33 =0, at this time
Figure GDA0002822610610000201
The step of establishing an eddy current magnetic field model comprises the following steps:
the vector of the induced magnetic field at the measurement point is represented as:
Figure GDA0002822610610000202
according to the property of directional cosine, there are:
Figure GDA0002822610610000203
u 1 u′ 1 +u 2 u′ 2 +u 3 u′ 3 ＝0
order:
Figure GDA0002822610610000204
the projection of the eddy magnetic field in the direction of the geomagnetic vector can be expressed as:
Figure GDA0002822610610000205
thus, the overall magnetic disturbance compensation model is:
Figure GDA0002822610610000206
it can be understood that after the extremely low frequency magnetic field model of the underwater vehicle in the air and the background magnetic interference compensation model are established, a simulation test method can be used for generating a regression equation set related to model parameters, and then each parameter in the model is solved, so that the method is applied to actual underwater vehicle detection. In addition, before practical application, the underwater vehicle model can be tested in a sea water pool, and model parameters are improved according to test results so as to further improve the detection capability of the underwater vehicle model.
In conclusion, the system and the method for detecting the extremely low frequency magnetic field of the underwater target from the air provided by the invention realize the effective and accurate detection of the extremely low frequency magnetic field of the underwater vehicle in the air, have wide application range and can be applied to fixed platforms at seaside, aircrafts and the like.
The above-described embodiments are intended to illustrate the objects, aspects and advantages of the present invention, and it should be understood that the above-described embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be within the scope of the present invention.

Claims (5)

1. A detection system for a very low frequency magnetic field of an underwater vehicle in the air is characterized by comprising a magnetic field sensor, a signal conditioning circuit and a data acquisition module; the magnetic field sensor is connected with the signal conditioning circuit, the signal conditioning circuit is connected with the data acquisition module, and the data acquisition module is connected with an external computer;
the magnetic field sensor is used for collecting magnetic field signals and transmitting the magnetic field signals to the signal conditioning circuit; the signal conditioning circuit comprises an amplifying circuit and a filtering circuit, and is used for processing a magnetic field signal and transmitting the processed magnetic field signal to the data acquisition module and the computer;
establishing an underwater vehicle in-air extremely-low frequency magnetic field model and a magnetic interference compensation model in computer software;
the method for establishing the underwater vehicle in-air extremely-low frequency magnetic field model comprises the following steps: the method comprises the following steps of taking a horizontal electric dipole and a vertical electric dipole as equivalent sources of a low-frequency magnetic field generated by an underwater vehicle, respectively modeling the low-frequency magnetic field generated by the horizontal electric dipole and the vertical electric dipole in an air layer, modeling the low-frequency magnetic field generated by the rotation of a magnetic dipole, and combining the three to serve as a low-frequency magnetic field model of the underwater vehicle in the air;
and, the step of modeling the extremely low frequency magnetic field generated by the rotation of the magnetic dipole specifically comprises:
the initial position of the magnetic dipole is used as an original point, the X axis points to the ship bow direction, the Y axis is the starboard direction, the Z axis is vertical downward, and the magnetic moment M = M x ·e x +m y ·e y +m z ·e z Wherein e is x 、e y And e z Unit vectors of X, Y, Z axes, respectively, m x 、m y And m z The components of the magnetic dipole on the X axis, the Y axis and the Z axis are respectively, and the magnetic dipole rotates around the X axis at a constant speed at an angular speed omega;
the total magnetic moment of the magnetic dipole at time t is M '= M' x ·e x +m' y ·e y +m' z ·e z The magnetic moment components in each direction are respectively:
Figure FDA0003838065620000011
then for any point in space (x, y, z), the magnetic field distribution of the magnetic dipole at the origin at time t is:
Figure FDA0003838065620000012
wherein mu 0 The magnetic permeability is vacuum magnetic permeability, r is the vector diameter of a magnetic dipole pointing measuring point, and r = x.e x +y·e y +z·e z ；
Writing equation (52) in three-component form, there is:
Figure FDA0003838065620000013
wherein, the first and the second end of the pipe are connected with each other,
Figure FDA0003838065620000014
the distance from the center of the magnetic dipole to the measuring point;
therefore, formula (53) can be modified by using the connection center of the propeller and the shaft as the origin, and assuming that the center position of the residual magnetic moment of the shafting is far from the origin R and forms an included angle with the negative direction of the Y axis
Figure FDA0003838065620000021
Then the magnetic dipole initial position x 0 ＝0，
Figure FDA0003838065620000022
Figure FDA0003838065620000023
The real-time position of the magnetic dipole can be written,
Figure FDA0003838065620000024
the magnetic field generated by the rotation of the magnetic dipole can be written as:
Figure FDA0003838065620000025
wherein the content of the first and second substances,
Figure FDA0003838065620000026
2. the system for detecting the extremely low frequency magnetic field in the air of the underwater vehicle as claimed in claim 1, wherein an instrumentation amplifier AD624 is adopted in the amplifying circuit; the magnetic field sensor adopts a three-axis fluxgate sensor Mag-13 or an inductive magnetic field sensor LEMI-120; the data acquisition module adopts an NI USB-6216 acquisition card.
3. The system for detecting the extremely low frequency magnetic field in the air of the underwater vehicle as claimed in claim 1, wherein the filter circuit is a band-pass filter formed by connecting a second-order high-pass active filter and a fourth-order low-pass active filter in series.
4. The system for detecting the extremely low frequency magnetic field in the air of an underwater vehicle as recited in claim 1, wherein said filter circuit is an adaptive filter based on the LMS adaptive algorithm.
5. A method for detecting the extremely low frequency magnetic field in the air of an underwater vehicle, which is characterized in that the system for detecting the extremely low frequency magnetic field in the air of the underwater vehicle according to any one of claims 1 to 4 is adopted, and the method comprises the following steps:
s1, establishing an extremely low frequency magnetic field model and a magnetic interference compensation model of an underwater vehicle in the air in computer software;
s2, collecting magnetic field signals through a magnetic field sensor, and transmitting the magnetic field signals to a signal conditioning circuit;
s3, amplifying the magnetic field signal through a signal conditioning circuit, filtering out part of interference signals in the magnetic field signal, and transmitting the processed magnetic field signal to a data acquisition module and a computer;
s4, further processing data of the data acquisition module through the underwater vehicle in-air extremely low-frequency magnetic field model and the magnetic interference compensation model to calculate an underwater vehicle in-air extremely low-frequency magnetic field;
in the step S1, the step of establishing the underwater vehicle in-air extremely-low frequency magnetic field model comprises the following steps: the method comprises the following steps of taking a horizontal electric dipole and a vertical electric dipole as equivalent sources of a low-frequency magnetic field generated by an underwater vehicle, respectively modeling the low-frequency magnetic field generated by the horizontal electric dipole and the vertical electric dipole in an air layer, modeling the low-frequency magnetic field generated by the rotation of a magnetic dipole, and combining the three to serve as a low-frequency magnetic field model of the underwater vehicle in the air;
the step of modeling the extremely low frequency magnetic field generated by the rotation of the magnetic dipole specifically includes:
the initial position of the magnetic dipole is used as an original point, the X axis points to the ship bow direction, the Y axis is the starboard direction, the Z axis is vertical downward, and the magnetic moment M = M x ·e x +m y ·e y +m z ·e z Wherein e is x 、e y And e z Unit vectors of X, Y, Z axes, respectively, m x 、m y And m z The components of the magnetic dipole on the X axis, the Y axis and the Z axis are respectively, and the magnetic dipole rotates around the X axis at a constant speed at an angular speed omega;
the total magnetic moment of the magnetic dipole at time t is M '= M' x ·e x +m' y ·e y +m' z ·e z The magnetic moment components in each direction are respectively:
Figure FDA0003838065620000031
then for any point in space (x, y, z), the magnetic field distribution of the magnetic dipole at the origin at time t is:
Figure FDA0003838065620000032
wherein mu 0 For vacuum permeability, r is the vector diameter of the magnetic dipole pointing measurement point, r = x · e x +y·e y +z·e z ；
Writing the equation (52) in three-component form, there is:
Figure FDA0003838065620000033
wherein the content of the first and second substances,
Figure FDA0003838065620000034
the distance from the center of the magnetic dipole to the measuring point;
therefore, formula (53) can be modified by using the connection center of the propeller and the shaft as the origin, and assuming that the center position of the residual magnetic moment of the shafting is far from the origin R and forms an included angle with the negative direction of the Y axis
Figure FDA0003838065620000035
Then the magnetic dipole initial position x 0 ＝0，
Figure FDA0003838065620000036
Figure FDA0003838065620000037
The real-time position of the magnetic dipole can be written,
Figure FDA0003838065620000038
the magnetic field generated by the rotation of the magnetic dipole can be written as:
Figure FDA0003838065620000041
wherein the content of the first and second substances,
Figure FDA0003838065620000042
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基于MSP432的船舶极低频磁场测量系统设计;孙玉绘 等;《水雷战与舰船防护》;20170831;第25卷(第3期);第52-55页 *

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