CN111123173B - Deep and far sea magnetic force abnormity detection system and detection method based on buoy - Google Patents

Deep and far sea magnetic force abnormity detection system and detection method based on buoy Download PDF

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CN111123173B
CN111123173B CN201911257126.6A CN201911257126A CN111123173B CN 111123173 B CN111123173 B CN 111123173B CN 201911257126 A CN201911257126 A CN 201911257126A CN 111123173 B CN111123173 B CN 111123173B
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buoy
magnetic
magnetic field
interference
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CN111123173A (en
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梁冠辉
裴彦良
刘保华
于凯本
刘晨光
阚光明
宗乐
吕彬
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First Institute of Oceanography MNR
National Deep Sea Center
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National Deep Sea Center
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/0206—Three-component magnetometers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/032—Measuring direction or magnitude of magnetic fields or magnetic flux using magneto-optic devices, e.g. Faraday or Cotton-Mouton effect
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
    • G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/42—Determining position

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Abstract

The invention discloses a deep and far sea magnetic anomaly detection system and a detection method based on a buoy, wherein the system comprises the buoy, a data collector, an attitude sensor, a wave sensor, a three-component fluxgate sensor and a cesium optical pump magnetic sensor are arranged in an instrument cabin of the buoy, and a Beidou communication terminal and GNSS positioning equipment are mounted at the top of the buoy; the method can eliminate the existing interference by calculating the interference magnetic field of the buoy and the background magnetic field of the seawater, has high sensitivity, can correctly identify the target, directly and accurately measure the direction of the target, and provides accurate data for military operations such as early warning, attack and the like.

Description

Deep and far sea magnetic force abnormity detection system and detection method based on buoy
Technical Field
The invention relates to the field of deep sea magnetic anomaly monitoring, in particular to a deep and far sea magnetic anomaly detection system and method based on buoys.
Background
Ships and submarines in the sea are comprehensive mechanical electronic equipment, and electromagnetic fields generated by communication equipment, electrical equipment, electronic circuits, power transmission lines and the like in the ships and the submarines are integrated; the shell is made of ferromagnetic substances such as steel, the residual magnetization of the ferromagnetic substances in the shell can generate a fixed magnetic field, the magnetic substances can generate an induction magnetic field under the magnetization effect of the earth magnetic field, the eddy magnetic field generated by cutting the earth magnetic field when the ferromagnetic substances in the shell move, the superposition of the magnetic fields can cause the distortion of the earth magnetic field to generate local magnetic anomaly of the earth magnetic field, and the overwater and underwater targets such as ships and submarines can be detected and identified by accurately measuring the local magnetic anomaly.
The American navy has been researching and applying aviation magnetic exploration potential technology from the 40 th century, a high-sensitivity magnetic exploration system is installed on an anti-diving airplane, and a target is distinguished and determined by measuring local magnetic anomaly caused by magnetic objects such as submarines in the ocean. The magnetometer and the accessory equipment with high sensitivity and the magnetic detection system formed by a reasonable and effective data acquisition and processing algorithm can correctly identify the target, directly and accurately measure the direction of the target and provide accurate data for military operations such as early warning, attack and the like.
In deep sea oceans, the ocean buoy becomes one of important means for ocean observation with the advantages of low cost, flexible arrangement and strong cruising ability, can carry out long-term continuous observation in a designated sea area, and carries out real-time data communication with land. Therefore, detection of magnetic anomalies by means of buoys is a relatively effective detection means, and no research on this aspect is available at present.
In the detection process of magnetic anomaly by using the buoy, the buoy platform can bring certain magnetic interference, and the main sources are three types: a fixed magnetic field, an eddy current magnetic field, and an induced magnetic field. The main sources of the fixed magnetic field are the magnetic property of the buoy body material, and the interference caused by the electromagnetic field generated when the electronic equipment in the buoy is electrified and works. The part of magnetic interference is irrelevant to an external geomagnetic field, has unchanged amplitude and direction, is a fixed magnetic field of the buoy platform, and has a larger proportion in the total magnetic interference of the buoy, and the amplitude is generally dozens of nT. The induced magnetic field is generated by the action of the geomagnetic field on the soft magnetic material (such as a buoy aluminum bracket) in the buoy, and the amplitude and the direction of the induced magnetic field are influenced by the relative position of the amplitude level buoy coordinate system of the geomagnetic field and the geomagnetic field. The eddy magnetic field is an electromagnetic field generated by induced current (i.e. eddy current) generated by cutting the geomagnetic field by a loop formed by the metal material of the buoy platform, and the amplitude and the direction of the electromagnetic field are influenced by the amplitude and the direction of the change rate of the geomagnetic field and the speed and the acceleration of the movement of the buoy platform.
Therefore, the magnetic interference caused by the buoy itself needs to be removed in the magnetic anomaly measurement algorithm to obtain more accurate magnetic anomaly information.
Disclosure of Invention
In order to solve the technical problems, the invention provides a buoy-based deep and far sea magnetic anomaly detection system and a detection method, so as to achieve the purposes of fixed-point long-term magnetic anomaly monitoring in a sensitive area in the sea and accurate monitoring results.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a deep and far sea magnetic force abnormity detection system based on a buoy comprises the buoy, wherein a data collector, an attitude sensor, a wave sensor, a three-component fluxgate sensor and a cesium optical pump magnetic force sensor are arranged in an instrument cabin of the buoy, and a Beidou communication terminal and GNSS positioning equipment are mounted at the top of the buoy;
the cesium optical pump magnetic sensor is used for measuring the total magnetic field value of the sea area where the buoy is located, and comprises a geomagnetic field, a buoy interference magnetic field, a seawater background magnetic field and target magnetic anomaly;
the three-component fluxgate sensor is used for measuring the three-axis component of the geomagnetic field of the sea area where the buoy is located in the buoy coordinate system;
the attitude sensor is used for measuring the yaw angle, roll angle and pitch angle of the buoy;
the data of the three-component fluxgate sensor and the data of the attitude sensor are used for magnetic interference compensation of the cesium optical pump magnetic sensor;
the wave sensor is used for measuring wave parameters of the sea area where the buoy is located, calculating a seawater background magnetic field generated by seawater motion of the sea area where the buoy is located, and improving the accuracy of magnetic anomaly measurement;
the GNSS positioning equipment provides time and position information for the magnetic data, and determines the magnetic inclination angle of the sea area where the buoy is located according to the position information;
the data are collected and stored by a data collector and are converted into a buoy coordinate system, magnetic interference compensation resolving and magnetic anomaly resolving are carried out, and found magnetic anomaly information is sent back to the land through a Beidou communication terminal.
In the scheme, the cesium optical pump magnetic sensor is placed at the bottommost layer of the instrument cabin, and the vertical central axis of the cesium optical pump magnetic sensor is superposed with the vertical central axis of the buoy; the installation position of the wave sensor is coincided with the gravity center of the whole buoy, the Z axis of the coordinate system of the wave sensor is coincided with the central axis of the buoy, and the X axis and the Y axis are parallel to the X axis and the Y axis of the coordinate system of the buoy; and the Z axis of the coordinate system of the attitude sensor is superposed with the vertical central axis of the buoy.
In the scheme, the data collector collects frequency signals output by the cesium optical pump magnetic force sensor through the timer interface, collects voltage signals output by the three-component fluxgate sensor through the 16-bit A/D port, collects data of the attitude sensor, the wave sensor and the GNSS positioning device through the serial port, is connected with the Beidou communication terminal through the serial port, and sends back found magnetic anomaly information to the land.
The deep and far sea magnetic force abnormity detection method based on the buoy adopts the deep and far sea magnetic force abnormity detection system based on the buoy, and comprises the following steps:
(1) performing magnetic interference compensation calculation on a buoy platform before the buoy comes out of the sea, wherein the magnetic interference compensation calculation comprises the measurement of a fixed magnetic interference scalar value of the buoy platform and the measurement and calculation of a magnetic interference compensation coefficient when the buoy platform runs;
(2) the buoy completing the magnetic interference compensation calculation is arranged in a designated sea area, and data of a cesium optical pump magnetic sensor, a three-component fluxgate sensor, an attitude data sensor, GNSS positioning equipment and a wave sensor are collected;
(3) substituting the fixed magnetic interference scalar value obtained by calculation in the step (1) and a magnetic interference compensation coefficient when the buoy platform runs, and the data of the cesium optical pump magnetic sensor, the three-component fluxgate sensor, the attitude data sensor and the GNSS positioning device acquired in the step (2) into a compensation equation to obtain a magnetic field value after the interference magnetic field of the buoy platform is eliminated;
(4) then carrying out spectrum analysis on the obtained magnetic field value after the interference magnetic field of the buoy platform is eliminated, and judging whether magnetic anomaly exists or not;
(5) calculating a seawater background magnetic field by using data measured by a wave sensor, and if no magnetic anomaly exists, subtracting the seawater background magnetic field from the magnetic field value obtained in the step (3) after the interference magnetic field of the buoy platform is eliminated, so as to obtain a geomagnetic field of a sea area where the buoy is located;
when magnetic anomaly occurs, the seawater background magnetic field and the geomagnetic field of the sea area where the buoy is located are subtracted by the magnetic field value which is obtained by calculation when the magnetic anomaly occurs and after the interference magnetic field of the buoy platform is eliminated, and a target magnetic anomaly value is obtained.
In the above scheme, in the step (1), the method for measuring the fixed magnetic interference scalar value of the buoy platform comprises the following steps: selecting a water tank with small magnetic field gradient, firstly measuring the geomagnetic field of the water tank area by using a cesium optical pump magnetic sensor, then installing the cesium optical pump magnetic sensor on a buoy, and statically placing the buoy in the water tank area to measure the magnetic field value, wherein the difference between the cesium optical pump magnetic sensor and the buoy is the fixed magnetic interference scalar value of the buoy platform.
In the above scheme, in the step (1), the method for measuring and calculating the magnetic interference compensation coefficient when the buoy platform operates is as follows:
and (2) putting the buoy into the selected water pool, simulating the actual motion state of the buoy during offshore work, and comprising three periodic actions of rotating, rolling and pitching by operating the buoy, namely rotating around three axes of a coordinate system for 3 times, wherein each action is performed for 6-8 seconds, the rotating action amplitude is 360 degrees, the rolling action amplitude and the pitching action amplitude are selected to be +/-30 degrees, the processes are repeated for four times at 0 degrees, 90 degrees, 180 degrees and 270 degrees of the heading angle of the buoy respectively, the data of the cesium optical pump magnetic sensor, the three-component fluxgate sensor, the attitude sensor and the GNSS positioning equipment are simultaneously acquired and stored by the buoy in the whole process, and then the magnetic interference compensation coefficient during the operation of the buoy platform is obtained through a magnetic compensation algorithm.
In a further technical scheme, a specific method for solving the magnetic interference compensation coefficient when the buoy platform runs by the magnetic compensation algorithm comprises the following steps:
firstly, establishing a coordinate system in a buoy platform system, and then establishing a magnetic interference model: selecting a cesium optical pump magnetic sensor as an origin of a buoy coordinate system, selecting an X axis and a Y axis of a buoy platform to be parallel to an X axis and a Y axis of an attitude sensor due to bilateral symmetry of a buoy, and selecting a Z axis to be vertically upward; the theta angle is an included angle between the heading and the magnetic north, namely a heading angle, the magnetic north direction is 0 degrees, the anticlockwise direction is positive, the pitch angle of the buoy is lambda, and the roll angle is psi; phi is a magnetic inclination angle which is related to the longitude and latitude of the buoy, the northern hemisphere is positive, and the southern hemisphere is negative;
the included angles between the geomagnetic field vector and the three coordinate axes are respectively set as follows: x, Y, Z, calculating the direction cosine of the magnetic field vector on three coordinate axes in any attitude according to the attitude angle and the magnetic inclination angle of the buoy as shown in the formula (1):
cosX＝cosφsinθcosψ+sinφsinψ， (1a)
cosY＝cosφcosθcosλ+sinφsinλ， (1b)
cosZ＝sinφcosψ-cosφsinθsinψ， (1c)
disturbing magnetic field value B of buoy platformdThe formula for calculation of (t) is:
Bd(t)＝Bpd+Bid(t)+Bed(t)， (2)
in the above formula, BpdA fixed magnetic field for the buoy platform; b isidAn induced magnetic field of the buoy platform; b isedAn eddy magnetic field for the buoy platform; t is time;
fixed magnetic field B of buoy platformpdThe vector expression in the buoy coordinate system is as follows:
Figure BDA0002310579730000041
in the above formula, the first and second carbon atoms are,
Figure BDA0002310579730000042
is a unit vector of three coordinate axes of the buoy platform, PX、PY、PZThe projections of the fixed magnetic field on the three coordinate axes are three fixed magnetic field interference coefficients in the magnetic interference model;
induced magnetic field B of buoy platformid(t) the formula of the calculation in three coordinate axes is as follows (4):
BidX(t)＝Be(t)[a11(cosX)2+a12cosXcosY+a13cosXcosZ]， (4a)
BidY(t)＝Be(t)[a21cosYcosX+a22(cosY)2+a23cosYcosZ]， (4b)
BidZ(t)＝Be(t)[a31cosZcosX+a32cosZcosY+a33(cosZ)2]， (4c)
in the above formula, Be(t) is the earth's magnetic field, a11A magnetic interference coefficient of an induced magnetic field generated on an X axis for the X component of the earth magnetic field; a is12A magnetic interference coefficient of an induced magnetic field generated on the Y axis for the X component of the earth magnetic field; a is13The magnetic interference coefficient of the induced magnetic field generated on the Z axis for the X component of the geomagnetic field; a is21A magnetic interference coefficient of an induced magnetic field generated on the X axis for the Y component of the earth magnetic field; a is22A magnetic interference coefficient of an induced magnetic field generated on the Y axis for the earth magnetic field Y component; a is23The magnetic interference coefficient of the induced magnetic field generated on the Z axis for the Y component of the earth magnetic field; a is31The magnetic interference coefficient of the induced magnetic field generated on the X axis for the Z component of the earth magnetic field; a is32Magnetic field of induced magnetic field generated on Y-axis for Z-component of earth magnetic fieldAn interference coefficient; a is33The magnetic interference coefficient of the induced magnetic field generated on the Z axis for the Z component of the earth magnetic field;
buoy platform eddy magnetic field Bed(t) the formula for the calculation in three coordinate axes is as follows (5):
Figure BDA0002310579730000051
Figure BDA0002310579730000052
Figure BDA0002310579730000053
in the above formula, b11A magnetic interference coefficient of an eddy current magnetic field generated on the X-axis for the X-component of the earth magnetic field; b12A magnetic interference coefficient of an eddy current magnetic field generated on the Y-axis for the X-component of the earth magnetic field; b13A magnetic interference coefficient of an eddy current magnetic field generated on the Z-axis for the X-component of the earth magnetic field; b21A magnetic interference coefficient of an eddy current magnetic field generated on the X-axis for the Y-component of the earth magnetic field; b22A magnetic interference coefficient of an eddy current magnetic field generated on the Y-axis for the Y-component of the earth magnetic field; b23The magnetic interference coefficient of the eddy current magnetic field generated on the Z axis for the Y component of the earth magnetic field; b31The magnetic interference coefficient of the eddy current magnetic field generated on the X axis for the Z component of the earth magnetic field; b32The magnetic interference coefficient of the eddy current magnetic field generated on the Y axis for the Z component of the earth magnetic field; b33The magnetic interference coefficient of the eddy current magnetic field generated on the Z axis for the Z component of the earth magnetic field;
the magnetic interference compensation equation is as follows:
Be(t)＝Bt(t)-Bd(t)， (6)
in the above formula, Be(t) is the geomagnetic field, which refers to the measurement value of the cesium optical pump magnetic sensor when no float is placed in the magnetic interference test; b ist(t) is the measured value of the cesium optical pump magnetic sensor after the buoy is placed in the magnetic interference test; b isd(t) for floating platformsThe value of the disturbing magnetic field is expressed by formulas (2), (3), (4) and (5), and after the formula (6) is expanded under the three-axis coordinate system of the buoy platform, the formula (7) is shown:
Be(t)cosX＝Bt(t)cosX-PX-BidX(t)-BedX(t)， (7a)
Be(t)cosY＝Bt(t)cosY-PY-BidY(t)-BedY(t)， (7b)
Be(t)cosZ＝Bt(t)cosZ-PZ-BidZ(t)-BedZ(t)， (7b)
all data collected in the step of measuring the magnetic interference coefficient of the buoy platform are substituted into a formula (7), and the magnetic interference compensation coefficient P can be obtained by solving an equation setX、PY、PZ、a11、a12、a13、a21、a22、a23、a31、a32、a33、b11、b12、b13、b21、b22、b23、b31、b32、b33。
In a further technical scheme, the specific method of the step (3) is as follows:
setting the magnetic field value of the buoy laying sea area to be H after eliminating the interference magnetic field of the buoy platform0(t) the reading value of the cesium optical pump magnetic sensor is Ht(t) heading angle theta, pitch angle lambda, roll angle phi and geomagnetic inclination angle phi of the buoy, wherein Ht(t), theta, lambda, psi and phi are obtained by real-time measurement and calculation of the buoy, then the theta, the lambda, the psi and the phi are substituted into the formula (1), and the cosines cosX, cosY and cosZ in three directions of the buoy coordinate system are solved in real time;
magnetic interference compensation coefficient PX、PY、PZ、a11、a12、a13、a21、a22、a23、a31、a32、a33、b11、b12、b13、b21、b22、b23、b31、b32、b33By passingThe magnetic interference compensation before the buoy is deployed is obtained, and the magnetic interference compensation is input into a data collector of the buoy before the buoy is deployed;
after the buoy is laid, the interference value of the fixed magnetic field of the buoy platform is unchanged, and the buoy can be used
Figure BDA0002310579730000061
Expressed, the calculation formula is:
Figure BDA0002310579730000062
h for induced magnetic field interference value of buoy platform after buoy deploymentid(t) represents the calculation formula in three coordinate axes as:
HidX(t)＝H0(t)[a11(cosX)2+a12cosXcosY+a13cosXcosZ]， (9a)
HidY(t)＝H0(t)[a21cosYcosX+a22(cosY)2+a23cosYcosZ]， (9b)
HidZ(t)＝H0(t)[a31cosZcosX+a32cosZcosY+a33(cosZ)2]， (9c)
h for eddy magnetic field interference value of buoy platform after buoy deploymented(t) represents the calculation formula in three coordinate axes as:
Figure BDA0002310579730000063
Figure BDA0002310579730000064
Figure BDA0002310579730000065
the value of the interference magnetic field of the buoy platform after the buoy is laid is set to be Hd(t) the formula is：
Figure BDA0002310579730000066
The magnetic interference compensation equation after the buoy is arranged is as follows:
H0(t)＝Ht(t)-Hd(t)， (12)
expanding the formula (12) under a three-axis coordinate system of the buoy platform as follows:
H0(t)cosX＝Ht(t)cosX-PX-HidX(t)-HedX(t)， (13a)
H0(t)cosY＝Ht(t)cosY-PY-HidY(t)-HedY(t)， (13b)
H0(t)cosZ＝Ht(t)cosZ-PZ-HidZ(t)-HedZ(t)， (13c)
in the above formula, only H0(t) is an unknown quantity, and can be obtained by solving an equation to obtain a magnetic field value H after the interference magnetic field of the buoy platform is eliminated0(t)。
In a further technical scheme, the specific method of the step (4) is as follows: for the obtained magnetic field value H after eliminating the interference magnetic field of the buoy platform0(t) carrying out fast Fourier transform and obtaining the frequency spectrum of the data, wherein the Fourier transform point is N, if the frequency spectrum amplitude at the frequency of 0.0015-0.5Hz is more than 5N, the data is considered to have magnetic anomaly, if the frequency spectrum amplitude is less than 5N, the data is considered to have no magnetic anomaly, and if the frequency spectrum amplitude exceeds 20N, the equipment is considered to have a fault.
In a further technical scheme, the specific method of the step (5) is as follows:
when no magnetic anomaly occurs, eliminating the magnetic field value H after the interference magnetic field of the buoy platform in the ocean0(t) consists of two parts: geomagnetic field He(t) and the background magnetic field H of seawaterw(t) that is
H0(t)＝He(t)+Hw(t)， (14)
Seawater background magnetic field Hw(t) the calculation formula is as follows：
Figure BDA0002310579730000071
In the above formula,. mu.0Is magnetic permeability, σ is electric conductivity, k is wave number, αnAmplitude of the nth wave, ωnIs the angular frequency of the nth wave, thetanAn included angle between the propagation direction of the nth wave and the X-axis direction is defined, and z is a vertical coordinate value of sea waves;
after the buoy is fixed in the sea area after deployment, the buoy is considered to be deployed in the geomagnetic field H of the sea areae(t) is a fixed value and is obtained from the equations (14) and (15);
after magnetic anomaly occurs, eliminating the magnetic field value H after the interference magnetic field of the buoy platform in the ocean0(t)' consists of three parts: geomagnetic field He(t) ocean background field Hw(t) and magnetic anomaly Hs(t) thus, magnetic anomaly H in the oceansThe formula for calculation of (t) is:
Hs(t)＝H0(t)′-He(t)-Hw(t)， (16)。
according to the deep and far sea magnetic anomaly detection system and the detection method based on the buoy, the magnetic anomaly monitoring is applied to the buoy, the manufacturing cost is low, the system is suitable for long-term fixed-point magnetic anomaly detection in deep and far sea, the existing interference can be eliminated by calculating the buoy interference magnetic field and the sea water background magnetic field, the sensitivity is high, the target can be correctly identified, the direction of the target can be directly and accurately determined, and accurate data can be provided for military operations such as early warning and attack.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below.
FIG. 1 is a schematic diagram of a system for detecting magnetic anomaly in deep and open sea based on buoys according to an embodiment of the present invention;
FIG. 2 is an established coordinate system of the buoy;
fig. 3 is a schematic flow chart of a method for detecting magnetic force anomaly in deep and open sea based on a buoy according to an embodiment of the present invention.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
The invention provides a buoy-based deep and open sea magnetic force anomaly detection system and a detection method.
The system comprises a buoy, a data collector, an attitude sensor, a wave sensor, a three-component fluxgate sensor and a cesium optical pump magnetic sensor are arranged in an instrument cabin of the buoy, and a Beidou communication terminal and GNSS positioning equipment are mounted at the top of the buoy;
the cesium optical pump magnetic sensor is used for measuring the total magnetic field value of a sea area where the buoy is located, and comprises a geomagnetic field (about 50000nT), a buoy interference magnetic field (about tens nT), a seawater background magnetic field (about tens nT) and a target magnetic anomaly (about tens nT); the three-component fluxgate sensor is used for measuring the three-axis component of the geomagnetic field of the sea area where the buoy is located in the buoy coordinate system; the attitude sensor is used for measuring the yaw angle, roll angle and pitch angle of the buoy; the data of the three-component fluxgate sensor and the data of the attitude sensor are used for magnetic interference compensation of the cesium optical pump magnetic sensor;
the wave sensor is used for measuring wave parameters of the sea area where the buoy is located and calculating a seawater background magnetic field generated by seawater motion of the sea area where the buoy is located, so that the accuracy of magnetic anomaly measurement is improved; the GNSS positioning equipment provides time and position information for the magnetic data, and determines the magnetic inclination angle of the sea area where the buoy is located according to the position information; the data are collected and stored by a data collector and are converted into a buoy coordinate system, magnetic interference compensation resolving and magnetic anomaly resolving are carried out, and found magnetic anomaly information is sent back to the land through a Beidou communication terminal.
In order to establish a buoy coordinate system conveniently, the cesium optical pump magnetic sensor is placed at the bottommost layer of the instrument chamber, and the vertical central axis of the cesium optical pump magnetic sensor is superposed with the vertical central axis of the buoy; the installation position of the wave sensor is coincided with the gravity center of the whole buoy, the Z axis of the coordinate system of the wave sensor is coincided with the central axis of the buoy, and the X axis and the Y axis are parallel to the X axis and the Y axis of the coordinate system of the buoy; and the Z axis of the coordinate system of the attitude sensor is superposed with the vertical central axis of the buoy.
In this embodiment, data collection station gathers the frequency signal of cesium optical pump magnetic force sensor output through the timer interface, gathers the voltage signal of three-component fluxgate sensor output through 16 AD ports, gathers attitude sensor, wave sensor and GNSS positioning device's data through the serial ports, is connected with big dipper communication terminal through the serial ports, sends the magnetic anomaly information of discovery back to land. The data update rate of the cesium optical pump magnetic sensor, the three-component fluxgate sensor, the attitude sensor and the GNSS positioning equipment is 10Hz, and the data update rate of the wave sensor is 20 Hz.
The high-sensitivity magnetic detection system is very sensitive to the magnetic interference response of a near field, and the magnetic interference of the buoy platform must be reduced as much as possible, namely the buoy material adopts nonmagnetic or weak magnetic material as much as possible, and the requirements of long-distance transportation and distribution of deep and far sea buoys and the applicability of the magnetic detection system on the buoy platform are considered. The buoy has the following main technical characteristics: the buoy adopts a disc type structure with the diameter less than or equal to 3 m; the floating body is made of PE materials, polyurea is sprayed on the surface of the floating body, the floating body is guaranteed to have enough strength and corrosion resistance, an instrument cabin and a battery cabin are arranged in the floating body, a high-sensitivity magnetic detection system is arranged in the instrument cabin, the central axis of the instrument cabin is overlapped with the central axis of the floating body, and a battery pack is arranged in the battery cabin; the anchor system comprises an anchor rope, a floating ball, an acoustic releaser, an anchor chain and an anchor block, wherein the anchor rope is a nylon rope or a polypropylene cable, the floating ball is a glass floating ball, connecting pieces close to the buoy are all made of aluminum, parts formed by ferromagnetic materials such as the acoustic releaser, the anchor chain and the anchor block are close to the sea bottom, and the distance from the parts to the buoy is more than 1000 meters.
A method for detecting magnetic force abnormality of deep and open sea based on buoys is shown in FIG. 3, and comprises the following steps:
firstly, magnetic interference compensation calculation of a buoy platform is carried out before the buoy comes out of the sea, and the magnetic interference compensation calculation comprises measurement of a fixed magnetic interference scalar value of the buoy platform and measurement and calculation of a magnetic interference compensation coefficient when the buoy platform runs;
the method for measuring the fixed magnetic interference scalar value of the buoy platform comprises the following steps: selecting a water tank with small magnetic field gradient, firstly measuring the geomagnetic field of the water tank area by using a cesium optical pump magnetic sensor, then installing the cesium optical pump magnetic sensor on a buoy, and statically placing the buoy in the water tank area to measure the magnetic field value, wherein the difference between the cesium optical pump magnetic sensor and the buoy is the fixed magnetic interference scalar value of the buoy platform.
The method for measuring and calculating the magnetic interference compensation coefficient during the operation of the buoy platform comprises the following steps:
and (2) putting the buoy into the selected water pool, simulating the actual motion state of the buoy during offshore work, and comprising three periodic actions of rotating, rolling and pitching by operating the buoy, namely rotating around three axes of a coordinate system for 3 times, wherein each action is performed for 6-8 seconds, the rotating action amplitude is 360 degrees, the rolling action amplitude and the pitching action amplitude are selected to be +/-30 degrees, the processes are repeated for four times at 0 degrees, 90 degrees, 180 degrees and 270 degrees of the heading angle of the buoy respectively, the data of the cesium optical pump magnetic sensor, the three-component fluxgate sensor, the attitude sensor and the GNSS positioning equipment are simultaneously acquired and stored by the buoy in the whole process, and then the magnetic interference compensation coefficient during the operation of the buoy platform is obtained through a magnetic compensation algorithm.
Specifically, the specific method for solving the magnetic interference compensation coefficient during the operation of the buoy platform by the magnetic compensation algorithm is as follows:
firstly, a coordinate system is established in a buoy platform system, as shown in fig. 2, and then a magnetic interference model is constructed: selecting a cesium optical pump magnetic sensor as an origin of a buoy coordinate system, selecting an X axis and a Y axis of a buoy platform to be parallel to an X axis and a Y axis of an attitude sensor due to bilateral symmetry of a buoy, and selecting a Z axis to be vertically upward; the theta angle is an included angle between the heading and the magnetic north, namely a heading angle, the magnetic north direction is 0 degrees, the anticlockwise direction is positive, the pitch angle of the buoy is lambda, and the roll angle is psi; phi is a magnetic inclination angle which is related to the longitude and latitude of the buoy, the northern hemisphere is positive, and the southern hemisphere is negative;
the included angles between the geomagnetic field vector and the three coordinate axes are respectively set as follows: x, Y, Z, calculating the direction cosine of the magnetic field vector on three coordinate axes in any attitude according to the attitude angle and the magnetic inclination angle of the buoy as shown in the formula (1):
cosX＝cosφsinθcosψ+sinφsinψ，(1a)
cosY＝cosφcosθcosλ+sinφsinλ，(1b)
cosZ＝sinφcosψ-cosφsinθsinψ，(1c)
disturbing magnetic field value B of buoy platformdThe formula for calculation of (t) is:
Bd(t)＝Bpd+Bid(t)+Bed(t)， (2)
in the above formula, BpdA fixed magnetic field for the buoy platform; b isidAn induced magnetic field of the buoy platform; b isedAn eddy magnetic field for the buoy platform; t is time;
fixed magnetic field B of buoy platformpdThe vector expression in the buoy coordinate system is as follows:
Figure BDA0002310579730000101
in the above formula, the first and second carbon atoms are,
Figure BDA0002310579730000102
is a unit vector of three coordinate axes of the buoy platform, PX、PY、PZThe projections of the fixed magnetic field on the three coordinate axes are three fixed magnetic field interference coefficients in the magnetic interference model;
induced magnetic field B of buoy platformid(t) the formula of the calculation in three coordinate axes is as follows (4):
BidX(t)＝Be(t)[a11(cosX)2+a12cosXcosY+a13cosXcosZ]， (4a)
BidY(t)＝Be(t)[a21cosYcosX+a22(cosY)2+a23cosYcosZ]， (4b)
BidZ(t)＝Be(t)[a31cosZcosX+a32cosZcosY+a33(cosZ)2]， (4c)
in the above formula, Be(t) is the earth's magnetic field, a11A magnetic interference coefficient of an induced magnetic field generated on an X axis for the X component of the earth magnetic field; a is12A magnetic interference coefficient of an induced magnetic field generated on the Y axis for the X component of the earth magnetic field; a is13The magnetic interference coefficient of the induced magnetic field generated on the Z axis for the X component of the geomagnetic field; a is21A magnetic interference coefficient of an induced magnetic field generated on the X axis for the Y component of the earth magnetic field; a is22A magnetic interference coefficient of an induced magnetic field generated on the Y axis for the earth magnetic field Y component; a is23The magnetic interference coefficient of the induced magnetic field generated on the Z axis for the Y component of the earth magnetic field; a is31The magnetic interference coefficient of the induced magnetic field generated on the X axis for the Z component of the earth magnetic field; a is32The magnetic interference coefficient of the induced magnetic field generated on the Y axis for the Z component of the earth magnetic field; a is33The magnetic interference coefficient of the induced magnetic field generated on the Z axis for the Z component of the earth magnetic field;
buoy platform eddy magnetic field Bed(t) the formula for the calculation in three coordinate axes is as follows (5):
Figure BDA0002310579730000103
Figure BDA0002310579730000104
Figure BDA0002310579730000111
in the above formula, b11A magnetic interference coefficient of an eddy current magnetic field generated on the X-axis for the X-component of the earth magnetic field; b12A magnetic interference coefficient of an eddy current magnetic field generated on the Y-axis for the X-component of the earth magnetic field; b13A magnetic interference coefficient of an eddy current magnetic field generated on the Z-axis for the X-component of the earth magnetic field; b21A magnetic interference coefficient of an eddy current magnetic field generated on the X-axis for the Y-component of the earth magnetic field; b22A magnetic interference coefficient of an eddy current magnetic field generated on the Y-axis for the Y-component of the earth magnetic field; b23For the Y component of the earth's magnetic field in the Z axisThe magnetic interference coefficient of the generated eddy magnetic field; b31The magnetic interference coefficient of the eddy current magnetic field generated on the X axis for the Z component of the earth magnetic field; b32The magnetic interference coefficient of the eddy current magnetic field generated on the Y axis for the Z component of the earth magnetic field; b33The magnetic interference coefficient of the eddy current magnetic field generated on the Z axis for the Z component of the earth magnetic field;
the magnetic interference compensation equation is as follows:
Be(t)＝Bt(t)-Bd(t)， (6)
in the above formula, Be(t) is the geomagnetic field, which refers to the measurement value of the cesium optical pump magnetic sensor when no float is placed in the magnetic interference test; b ist(t) is the measured value of the cesium optical pump magnetic sensor after the buoy is placed in the magnetic interference test; b isdAnd (t) is the value of the disturbing magnetic field of the buoy platform, and is represented by formulas (2), (3), (4) and (5), and after the formula (6) is expanded under a triaxial coordinate system of the buoy platform, the formula (7) is shown:
Be(t)cosX＝Bt(t)cosX-PX-BidX(t)-BedX(t)， (7a)
Be(t)cosY＝Bt(t)cosY-PY-BidY(t)-BedY(t)， (7b)
Be(t)cosZ＝Bt(t)cosZ-PZ-BidZ(t)-BedZ(t)， (7b)
all data collected in the step of measuring the magnetic interference coefficient of the buoy platform are substituted into a formula (7), and the magnetic interference compensation coefficient P can be obtained by solving an equation setX、PY、PZ、a11、a12、a13、a21、a22、a23、a31、a32、a33、b11、b12、b13、b21、b22、b23、b31、b32、b33。
(2) The buoy completing the magnetic interference compensation calculation is arranged in a designated sea area, and data of a cesium optical pump magnetic sensor, a three-component fluxgate sensor, an attitude data sensor, GNSS positioning equipment and a wave sensor are collected;
(3) substituting the fixed magnetic interference scalar value obtained by calculation in the step (1) and a magnetic interference compensation coefficient when the buoy platform runs, and the data of the cesium optical pump magnetic sensor, the three-component fluxgate sensor, the attitude data sensor and the GNSS positioning device acquired in the step (2) into a compensation equation to obtain a magnetic field value after the interference magnetic field of the buoy platform is eliminated;
setting the magnetic field value of the buoy laying sea area to be H after eliminating the interference magnetic field of the buoy platform0(t) the reading value of the cesium optical pump magnetic sensor is Ht(t) heading angle theta, pitch angle lambda, roll angle phi and geomagnetic inclination angle phi of the buoy, wherein Ht(t), lambda, psi and phi are obtained by real-time measurement and calculation of the buoy, then theta, lambda, psi and phi are substituted into the formula (1), and cosines cosX, cosY and cosZ in three directions of the buoy coordinate system are solved in real time;
magnetic interference compensation coefficient PX、PY、PZ、a11、a12、a13、a21、a22、a23、a31、a32、a33、b11、b12、b13、b21、b22、b23、b31、b32、b33The magnetic interference compensation is obtained in the magnetic interference compensation work before the buoy is arranged, and the magnetic interference compensation is input into a data collector of the buoy before the buoy is arranged;
after the buoy is laid, the interference value of the fixed magnetic field of the buoy platform is unchanged, and the buoy can be used
Figure BDA0002310579730000121
Expressed, the calculation formula is:
Figure BDA0002310579730000122
h for induced magnetic field interference value of buoy platform after buoy deploymentid(t) represents the calculation formula in three coordinate axes as:
HidX(t)＝H0(t)[a11(cosX)2+a12cosXcosY+a13cosXcosZ]， (9a)
HidY(t)＝H0(t)[a21cosYcosX+a22(cosY)2+a23cosYcosZ]， (9b)
HidZ(t)＝H0(t)[a31cosZcosX+a32cosZcosY+a33(cosZ)2]， (9c)
h for eddy magnetic field interference value of buoy platform after buoy deploymented(t) represents the calculation formula in three coordinate axes as:
Figure BDA0002310579730000123
Figure BDA0002310579730000124
Figure BDA0002310579730000125
the value of the interference magnetic field of the buoy platform after the buoy is laid is set to be Hd(t) the calculation formula is:
Figure BDA0002310579730000126
the magnetic interference compensation equation after the buoy is arranged is as follows:
H0(t)＝Ht(t)-Hd(t)， (12)
expanding the formula (12) under a three-axis coordinate system of the buoy platform as follows:
H0(t)cosX＝Ht(t)cosX-PX-HidX(t)-HedX(t)， (13a)
H0(t)cosY＝Ht(t)cosY-PY-HidY(t)-HedY(t)， (13b)
H0(t)cosZ＝Ht(t)cosZ-PZ-HidZ(t)-HedZ(t)， (13c)
in the above formula, only H0(t) is an unknown quantity, and can be obtained by solving an equation to obtain a magnetic field value H after the interference magnetic field of the buoy platform is eliminated0(t)。
(4) Then carrying out spectrum analysis on the obtained magnetic field value after the interference magnetic field of the buoy platform is eliminated, and judging whether magnetic anomaly exists or not;
for the obtained magnetic field value H after eliminating the interference magnetic field of the buoy platform0(t) carrying out fast Fourier transform and obtaining the frequency spectrum of the data, wherein the Fourier transform point is N, if the frequency spectrum amplitude at the frequency of 0.0015-0.5Hz is more than 5N, the data is considered to have magnetic anomaly, if the frequency spectrum amplitude is less than 5N, the data is considered to have no magnetic anomaly, and if the frequency spectrum amplitude exceeds 20N, the equipment is considered to have a fault.
(5) Calculating a seawater background magnetic field by using data measured by a wave sensor, and if no magnetic anomaly exists, subtracting the seawater background magnetic field from the magnetic field value obtained in the step (3) after the interference magnetic field of the buoy platform is eliminated, so as to obtain a geomagnetic field of a sea area where the buoy is located;
when magnetic anomaly occurs, the seawater background magnetic field and the geomagnetic field of the sea area where the buoy is located are subtracted by the magnetic field value which is obtained by calculation when the magnetic anomaly occurs and after the interference magnetic field of the buoy platform is eliminated, and a target magnetic anomaly value is obtained.
When no magnetic anomaly occurs, eliminating the magnetic field value H after the interference magnetic field of the buoy platform in the ocean0(t) consists of two parts: geomagnetic field He(t) and the background magnetic field H of seawaterw(t) that is
H0(t)＝He(t)+Hw(t)， (14)
Seawater background magnetic field Hw(t) the calculation formula is as follows:
Figure BDA0002310579730000131
in the above formula,. mu.0Is magnetic permeability, σ is electric conductivity, k is wave number, αnAmplitude of nth wave，ωnIs the angular frequency of the nth wave, thetanAn included angle between the propagation direction of the nth wave and the X-axis direction is defined, and z is a vertical coordinate value of sea waves;
after the buoy is fixed in the sea area after deployment, the buoy is considered to be deployed in the geomagnetic field H of the sea areae(t) is a fixed value and is obtained from the equations (14) and (15);
after magnetic anomaly occurs, eliminating the magnetic field value H after the interference magnetic field of the buoy platform in the ocean0(t)' consists of three parts: geomagnetic field He(t) ocean background field Hw(t) and magnetic anomaly Hs(t) thus, magnetic anomaly H in the oceansThe formula for calculation of (t) is:
Hs(t)＝H0(t)′-He(t)-Hw(t)， (16)。
the previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (9)

1. A deep and far sea magnetic force abnormity detection method based on a buoy is adopted, and the deep and far sea magnetic force abnormity detection system based on the buoy is characterized by comprising the buoy, a data collector, an attitude sensor, a wave sensor, a three-component fluxgate sensor and a cesium optical pump magnetic force sensor are arranged in an instrument cabin of the buoy, and a Beidou communication terminal and GNSS positioning equipment are mounted at the top of the buoy;
the cesium optical pump magnetic sensor is used for measuring the total magnetic field value of the sea area where the buoy is located, and comprises a geomagnetic field, a buoy interference magnetic field, a seawater background magnetic field and target magnetic anomaly;
the three-component fluxgate sensor is used for measuring the three-axis component of the geomagnetic field of the sea area where the buoy is located in the buoy coordinate system;
the attitude sensor is used for measuring the yaw angle, roll angle and pitch angle of the buoy;
the data of the three-component fluxgate sensor and the data of the attitude sensor are used for magnetic interference compensation of the cesium optical pump magnetic sensor;
the wave sensor is used for measuring wave parameters of the sea area where the buoy is located, calculating a seawater background magnetic field generated by seawater motion of the sea area where the buoy is located, and improving the accuracy of magnetic anomaly measurement;
the GNSS positioning equipment provides time and position information for the magnetic data, and determines the magnetic inclination angle of the sea area where the buoy is located according to the position information;
the data are collected and stored by a data collector and are converted into a buoy coordinate system, magnetic interference compensation resolving and magnetic anomaly resolving are carried out, and found magnetic anomaly information is sent back to the land through a Beidou communication terminal;
the detection method comprises the following steps:
(1) performing magnetic interference compensation calculation on a buoy platform before the buoy comes out of the sea, wherein the magnetic interference compensation calculation comprises the measurement of a fixed magnetic interference scalar value of the buoy platform and the measurement and calculation of a magnetic interference compensation coefficient when the buoy platform runs;
(2) the buoy completing the magnetic interference compensation calculation is arranged in a designated sea area, and data of a cesium optical pump magnetic sensor, a three-component fluxgate sensor, an attitude sensor, GNSS positioning equipment and a wave sensor are collected;
(3) substituting the fixed magnetic interference scalar value obtained by calculation in the step (1) and a magnetic interference compensation coefficient when the buoy platform runs, and the data of the cesium optical pump magnetic sensor, the three-component fluxgate sensor, the attitude sensor and the GNSS positioning device acquired in the step (2) into a compensation equation to obtain a magnetic field value after the interference magnetic field of the buoy platform is eliminated;
(4) then carrying out spectrum analysis on the obtained magnetic field value after the interference magnetic field of the buoy platform is eliminated, and judging whether magnetic anomaly exists or not;
(5) calculating a seawater background magnetic field by using data measured by a wave sensor, and if no magnetic anomaly exists, subtracting the seawater background magnetic field from the magnetic field value obtained in the step (3) after the interference magnetic field of the buoy platform is eliminated, so as to obtain a geomagnetic field of a sea area where the buoy is located;
when magnetic anomaly occurs, the seawater background magnetic field and the geomagnetic field of the sea area where the buoy is located are subtracted by the magnetic field value which is obtained by calculation when the magnetic anomaly occurs and after the interference magnetic field of the buoy platform is eliminated, and a target magnetic anomaly value is obtained.
2. The buoy-based deep and open sea magnetic force anomaly detection method as claimed in claim 1, wherein the cesium optical pump magnetic force sensor is placed at the bottommost layer of the instrument chamber, and the vertical central axis of the cesium optical pump magnetic force sensor coincides with the vertical central axis of the buoy; the installation position of the wave sensor is coincided with the gravity center of the whole buoy, the Z axis of the coordinate system of the wave sensor is coincided with the central axis of the buoy, and the X axis and the Y axis are respectively parallel to the X axis and the Y axis of the coordinate system of the buoy; and the Z axis of the coordinate system of the attitude sensor is superposed with the vertical central axis of the buoy.
3. The buoy-based deep open sea magnetic force anomaly detection method according to claim 1, wherein the data collector collects frequency signals output by a cesium optical pump magnetic force sensor through a timer interface, collects voltage signals output by a three-component fluxgate sensor through a 16-bit A/D port, collects data of an attitude sensor, a wave sensor and GNSS positioning equipment through a serial port, is connected with a Beidou communication terminal through the serial port, and sends found magnetic anomaly information back to the land.
4. The method for detecting magnetic force anomaly in deep and open sea based on buoy of claim 1, wherein in the step (1), the fixed magnetic interference scalar value of the buoy platform is determined by the following method: selecting a water tank with small magnetic field gradient, firstly measuring the geomagnetic field of the water tank area by using a cesium optical pump magnetic sensor, then installing the cesium optical pump magnetic sensor on a buoy, and statically placing the buoy in the water tank area to measure the magnetic field value, wherein the difference between the cesium optical pump magnetic sensor and the buoy is the fixed magnetic interference scalar value of the buoy platform.
5. The method for detecting the magnetic force anomaly in the deep and open sea based on the buoy as claimed in claim 4, wherein in the step (1), the method for measuring and calculating the magnetic interference compensation coefficient when the buoy platform operates is as follows:
and (2) putting the buoy into the selected water pool, simulating the actual motion state of the buoy during offshore work, and comprising three periodic actions of rotating, rolling and pitching by operating the buoy, namely rotating around three axes of a coordinate system for 3 times, wherein each action is performed for 6-8 seconds, the rotating action amplitude is 360 degrees, the rolling action amplitude and the pitching action amplitude are selected to be +/-30 degrees, the processes are repeated for four times at 0 degrees, 90 degrees, 180 degrees and 270 degrees of the heading angle of the buoy respectively, the data of the cesium optical pump magnetic sensor, the three-component fluxgate sensor, the attitude sensor and the GNSS positioning equipment are simultaneously acquired and stored by the buoy in the whole process, and then the magnetic interference compensation coefficient during the operation of the buoy platform is obtained through a magnetic compensation algorithm.
6. The buoy-based deep open sea magnetic force anomaly detection method according to claim 5, wherein the specific method for solving the magnetic interference compensation coefficient during the operation of the buoy platform by the magnetic compensation algorithm is as follows:
firstly, establishing a coordinate system in a buoy platform system, and then establishing a magnetic interference model: selecting a cesium optical pump magnetic sensor as an origin of a buoy coordinate system, selecting an X axis and a Y axis of a buoy platform to be parallel to an X axis and a Y axis of an attitude sensor due to bilateral symmetry of a buoy, and selecting a Z axis to be vertically upward; the theta angle is an included angle between the heading and the magnetic north, namely a heading angle, the magnetic north direction is 0 degrees, the anticlockwise direction is positive, the pitch angle of the buoy is lambda, and the roll angle is psi; phi is a magnetic inclination angle which is related to the longitude and latitude of the buoy, the northern hemisphere is positive, and the southern hemisphere is negative;
the included angles between the geomagnetic field vector and the three coordinate axes are respectively set as follows: x, Y, Z, calculating the direction cosine of the magnetic field vector on three coordinate axes in any attitude according to the attitude angle and the magnetic inclination angle of the buoy as shown in the formulas (1a), (1b) and (1 c):
cosX＝cosφsinθcosψ+sinφsinψ， (1a)
cosY＝cosφcosθcosλ+sinφsinλ， (1b)
cosZ＝sinφcosψ-cosφsinθsinψ， (1c)
disturbing magnetic field value B of buoy platformdThe formula for calculation of (t) is:
Bd(t)＝Bpd+Bid(t)+Bed(t)， (2)
in the above formula, BpdA fixed magnetic field for the buoy platform; b isidAn induced magnetic field of the buoy platform; b isedAn eddy magnetic field for the buoy platform; t is time;
fixed magnetic field B of buoy platformpdThe vector expression in the buoy coordinate system is as follows:
Figure FDA0003243897670000035
in the above formula, the first and second carbon atoms are,
Figure FDA0003243897670000032
is a unit vector of three coordinate axes of the buoy platform, PX、PY、PZThe projections of the fixed magnetic field on the three coordinate axes are three fixed magnetic field interference coefficients in the magnetic interference model;
induced magnetic field B of buoy platformid(t) the formula for the projection on the three coordinate axes is given by equations (4a), (4b) and (4 c):
BidX(t)＝Be(t)[a11(cosX)2+a12 cosX cosY+a13 cosX cosZ]， (4a)
BidY(t)＝Be(t)[a21 cosY cosX+a22(cosY)2+a23 cosY cosZ]， (4b)
BidZ(t)＝Be(t)[a31 cosZ cosX+a32 cosZ cosY+a33(cosZ)2]， (4c)
in the above formula, Be(t) is the earth's magnetic field, a11A magnetic interference coefficient of an induced magnetic field generated on an X axis for the X component of the earth magnetic field; a is12A magnetic interference coefficient of an induced magnetic field generated on the Y axis for the X component of the earth magnetic field; a is13The magnetic interference coefficient of the induced magnetic field generated on the Z axis for the X component of the geomagnetic field; a is21A magnetic interference coefficient of an induced magnetic field generated on the X axis for the Y component of the earth magnetic field; a is22A magnetic interference coefficient of an induced magnetic field generated on the Y axis for the earth magnetic field Y component; a is23The magnetic interference coefficient of the induced magnetic field generated on the Z axis for the Y component of the earth magnetic field; a is31The magnetic interference coefficient of the induced magnetic field generated on the X axis for the Z component of the earth magnetic field; a is32The magnetic interference coefficient of the induced magnetic field generated on the Y axis for the Z component of the earth magnetic field; a is33The magnetic interference coefficient of the induced magnetic field generated on the Z axis for the Z component of the earth magnetic field;
buoy platform eddy magnetic field Bed(t) the formula for the projection on the three coordinate axes is given by equations (5a), (5b) and (5 c):
Figure FDA0003243897670000033
Figure FDA0003243897670000034
Figure FDA0003243897670000041
in the above formula, b11A magnetic interference coefficient of an eddy current magnetic field generated on the X-axis for the X-component of the earth magnetic field; b12A magnetic interference coefficient of an eddy current magnetic field generated on the Y-axis for the X-component of the earth magnetic field; b13A magnetic interference coefficient of an eddy current magnetic field generated on the Z-axis for the X-component of the earth magnetic field; b21A magnetic interference coefficient of an eddy current magnetic field generated on the X-axis for the Y-component of the earth magnetic field; b22Magnetic interference system of eddy magnetic field generated on Y-axis for Y-component of earth magnetic fieldCounting; b23The magnetic interference coefficient of the eddy current magnetic field generated on the Z axis for the Y component of the earth magnetic field; b31The magnetic interference coefficient of the eddy current magnetic field generated on the X axis for the Z component of the earth magnetic field; b32The magnetic interference coefficient of the eddy current magnetic field generated on the Y axis for the Z component of the earth magnetic field; b33The magnetic interference coefficient of the eddy current magnetic field generated on the Z axis for the Z component of the earth magnetic field;
the magnetic interference compensation equation is as follows:
Be(t)＝Bt(t)-Bd(t)， (6)
in the above formula, Be(t) is the geomagnetic field, which refers to the measurement value of the cesium optical pump magnetic sensor when no float is placed in the magnetic interference test; b ist(t) is the measured value of the cesium optical pump magnetic sensor after the buoy is placed in the magnetic interference test; b isdAnd (t) is the value of the disturbing magnetic field of the buoy platform, which is expressed by formulas (2), (3), (4a), (4b), (4c), (5a), (5b) and (5c), and after the formula (6) is developed under the triaxial coordinate system of the buoy platform, the formula (7a), (7b) and (7c) are shown in the specification:
Be(t)cosX＝Bt(t)cosX-PX-BidX(t)-BedX(t)， (7a)
Be(t)cosY＝Bt(t)cosY-PY-BidY(t)-BedY(t)， (7b)
Be(t)cosZ＝Bt(t)cosZ-PZ-BidZ(t)-BedZ(t)， (7b)
substituting all data collected in the step of measuring the magnetic interference coefficient of the buoy platform into equations (7a), (7b) and (7c), solving an equation set to obtain a magnetic interference compensation coefficient PX、PY、PZ、a11、a12、a13、a21、a22、a23、a31、a32、a33、b11、b12、b13、b21、b22、b23、b31、b32、b33。
7. The buoy-based deep open sea magnetic force anomaly detection method according to claim 6, wherein the specific method of the step (3) is as follows:
setting the magnetic field value of the buoy laying sea area to be H after eliminating the interference magnetic field of the buoy platform0(t) the reading value of the cesium optical pump magnetic sensor is Ht(t) heading angle theta, pitch angle lambda, roll angle phi and geomagnetic inclination angle phi of the buoy, wherein Ht(t), theta, lambda, psi and phi are obtained by real-time measurement and calculation of the buoy, then the theta, the lambda, the psi and the phi are substituted into the formula (1), and the cosines cosX, cosY and cosZ in three directions of the buoy coordinate system are solved in real time;
magnetic interference compensation coefficient PX、PY、PZ、a11、a12、a13、a21、a22、a23、a31、a32、a33、b11、b12、b13、b21、b22、b23、b31、b32、b33The magnetic interference compensation is obtained in the magnetic interference compensation work before the buoy is arranged, and the magnetic interference compensation is input into a data collector of the buoy before the buoy is arranged;
after the buoy is laid, the interference value of the fixed magnetic field of the buoy platform is unchanged, and the buoy can be used
Figure FDA0003243897670000051
Expressed, the calculation formula is:
Figure FDA0003243897670000052
h for induced magnetic field interference value of buoy platform after buoy deploymentid(t) represents the formula for the projection on the three coordinate axes:
HidX(t)＝H0(t)[a11(cosX)2+a12 cosX cosY+a13 cosX cosZ]， (9a)
HidY(t)＝H0(t)[a21 cosY cosX+a22(cosY)2+a23 cosY cosZ]， (9b)
HidZ(t)＝H0(t)[a31 cosZ cosX+a32 cosZ cosY+a33(cosZ)2]， (9c)
h for eddy magnetic field interference value of buoy platform after buoy deploymented(t) represents the formula for the projection on the three coordinate axes:
Figure FDA0003243897670000053
Figure FDA0003243897670000054
Figure FDA0003243897670000055
the value of the interference magnetic field of the buoy platform after the buoy is laid is set to be Hd(t) the calculation formula is:
Figure FDA0003243897670000056
the magnetic interference compensation equation after the buoy is arranged is as follows:
H0(t)＝Ht(t)-Hd(t)， (12)
expanding the formula (12) under a three-axis coordinate system of the buoy platform as follows:
H0(t)cosX＝Ht(t)cosX-PX-HidX(t)-HedX(t)， (13a)
H0(t)cosY＝Ht(t)cosY-PY-HidY(t)-HedY(t)， (13b)
H0(t)cosZ＝Ht(t)cosZ-PZ-HidZ(t)-HedZ(t)， (13c)
the upper typeIn (1), only H0(t) is an unknown quantity, and can be obtained by solving an equation to obtain a magnetic field value H after the interference magnetic field of the buoy platform is eliminated0(t)。
8. The buoy-based deep open sea magnetic force anomaly detection method according to claim 7, wherein the specific method of the step (4) is as follows: for the obtained magnetic field value H after eliminating the interference magnetic field of the buoy platform0(t) carrying out fast Fourier transform and obtaining the frequency spectrum of the buoy platform, setting the number of Fourier transform points as N, and if the frequency spectrum amplitude is more than 5N at the frequency of 0.0015-0.5Hz, considering that the obtained magnetic field value H after the interference magnetic field of the buoy platform is eliminated0(t) magnetic anomaly exists, and if the magnetic anomaly is less than 5N, the obtained magnetic field value H after the interference magnetic field of the buoy platform is eliminated is considered0(t) there is no magnetic anomaly, and if it exceeds 20N, the device is considered to be malfunctioning.
9. The buoy-based deep open sea magnetic force anomaly detection method according to claim 7, wherein the specific method of the step (5) is as follows:
when no magnetic anomaly occurs, eliminating the magnetic field value H after the interference magnetic field of the buoy platform in the ocean0(t) consists of two parts: geomagnetic field He(t) and the background magnetic field H of seawaterw(t) that is
H0(t)＝He(t)+Hw(t)， (14)
Seawater background magnetic field Hw(t) the calculation formula is as follows:
Figure FDA0003243897670000061
in the above formula,. mu.0Is magnetic permeability, σ is electric conductivity, k is wave number, αnAmplitude of the nth wave, ωnIs the angular frequency of the nth wave, thetanAn included angle between the propagation direction of the nth wave and the X-axis direction is defined, and z is a vertical coordinate value of sea waves;
the buoy is arranged behind the fixed sea areaConsidering that the buoy is arranged in the geomagnetic field H of the sea areae(t) is a fixed value and is obtained from the equations (14) and (15);
after magnetic anomaly occurs, eliminating the magnetic field value H after the interference magnetic field of the buoy platform in the ocean0(t)' consists of three parts: geomagnetic field He(t) ocean background field Hw(t) and magnetic anomaly Hs(t) thus, magnetic anomaly H in the oceansThe formula for calculation of (t) is:
Hs(t)＝H0(t)′-He(t)-Hw(t)， (16)。
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