JP2015101158A - Device and method for estimating magnetism of hull - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable only magnetism of a hull to be simply and rapidly estimated by deducting a magnetic field caused by UEP from an output value of a magnetic sensor installed inboard.SOLUTION: Magnetic sensors 6-1 to 6-3 and a processor 3, which are installed inboard, and electrodes 1-1 to 1-2 and an electrical conductivity meter 4, which serve as UEP sensors mounted on a bottom, are used. The processor 3 determines a magnetic field caused by UEP in a magnetic sensor position from measurement values of the electrodes 1-1 to 1-2 and the electrical conductivity meter 4, determines the magnetic field based on magnetism of a hull by deducting the magnetic field by UEP from an output value of the magnetic sensor, and estimates the magnetism of the hull from the magnetic field based on the magnetism of the hull.

Description

  The present invention relates to a magnetic sensor for estimating hull magnetism based on measurement values from a magnetic sensor installed in a ship, an underwater electric potential (UEP) sensor installed in a ship bottom, and an underwater conductivity meter. About.

  A magnetic field generated from a ship is formed by superimposing a magnetic field generated by hull magnetism composed of permanent magnetism and induced magnetism (due to geomagnetism) and a UEP-induced magnetic field generated by a corrosion-proof current flowing through the bottom of the ship. .

  Hull magnetism is generated inside a ship, and the generation source thereof is a ship body or a ship-mounted product that is a magnetic material.

  The UEP-induced magnetic field is generated outside the ship, and the generation mechanism is that corrosion occurs when a ship component composed of various dissimilar metals touches seawater, which is an electrical conductor. Therefore, as a means to prevent hull corrosion, the galvanic anode method in which sacrificial protective zinc is stretched around the hull instead of the hull, and current is applied to keep the hull potential constant to prevent corrosion. There is an external power supply anti-corrosion system. Although these methods can prevent the hull from being corroded, UEP is generated around the hull instead, thereby generating a magnetic field.

  Since the magnetic field generated from the ship is subject to threats such as mines or detectors equipped with magnetic sensors, it is necessary to reduce the magnetic field to ensure safe navigation of the ship.

  Patent Document 1 below estimates the ship's magnetism from the output value of the magnetic sensor installed in the ship with reference to the measurement value from the magnetic sensor installed on the seabed, and determines the demagnetizing coil current value based on the estimated value. It is about the system.

  The following Patent Document 2 relates to a method and apparatus for reducing UEP generated from a ship by applying a current into the sea from an electrode installed outside the hull.

JP-A-8-78234 JP 2011-88542 A

  FIG. 2 is an explanatory view schematically showing the magnetic field generated from the hull 20. The hull magnetism 21 is visualized by a bar magnet, and the hull 20 made of, for example, a steel material and a propulsion made of, for example, a brass material. The UEP-induced magnetic field 25 generated by the UEP current 24 flowing when the container 23 comes into contact with water is shown.

  2, the demagnetizing coils 22-1 to 22-2 are disposed so as to surround the hull magnetism 21, and the energization amount of the demagnetizing coils 22-1 to 22-2 is adjusted to thereby adjust the hull magnetism 21. Although the UEP-induced magnetic field 25 generated outside the hull 20 cannot be surrounded by the degaussing coils 22-1 to 22-2, the magnetic field can be effectively reduced. Can not.

  On the other hand, the UEP-induced magnetic field 25 shown in FIG. 2 can be reduced by reducing the UEP current 24 that causes the generation of the UEP-induced magnetic field according to, for example, Patent Document 2 described above. Can not be reduced.

  Since the demagnetizing coil 22 installed in the hull is a device that apparently reduces the amount of magnetism of the hull magnetism 21, when effectively reducing magnetism by the degaussing coil 22, It is necessary to be able to estimate only the magnetic quantity of the hull magnetism 21.

  FIG. 3 schematically shows the magnetic field for each cause of occurrence, and the magnetic sensor 6 installed in the hull 20 outputs a value in which a magnetic field 31 caused by the hull magnetism and a magnetic field 33 caused by the UEP current 24 are superimposed. Therefore, it is necessary to remove the influence of the UEP-induced magnetic field 33 from the output value of the magnetic sensor 6.

  In addition to the magnetic field due to the hull magnetism, the UEP-induced magnetic field is superimposed on the output value of the magnetic sensor installed on the ship, which is the basis for calculating the demagnetizing current value in Patent Document 1, thus making the invention more effective. Therefore, there is room for improvement in a method for estimating only ship magnetism, such as subtracting the UEP-induced magnetic field from the output value of the onboard magnetic sensor.

  The present invention has been made paying attention to this problem, and a hull magnetic estimator which can easily and quickly estimate only the hull magnetism by subtracting the UEP-induced magnetic field from the output value of the magnetic sensor installed in the hull. And to provide a method.

One embodiment of the present invention is a ship body magnetic estimator. This ship magnetism estimation device includes a magnetic sensor and a processor installed in the ship, a UEP sensor and an electric conductivity meter attached to the ship bottom,
The processor obtains a UEP-induced magnetic field at the magnetic sensor position from the measured values of the UEP sensor and an electric conductivity meter, and subtracts the UEP-induced magnetic field from the output value of the magnetic sensor to obtain a magnetic field based on ship magnetism. The hull magnetism is estimated from the magnetic field based on the hull magnetism.

  The said aspect WHEREIN: It is good to provide the indicator which displays the estimation result of the said ship body magnetism.

  The said aspect WHEREIN: It is good to provide the recording apparatus which records the estimation result of the said ship body magnetism.

  Another embodiment of the present invention is a hull magnetic field estimation method. This ship magnetism estimation method uses a magnetic sensor and a processor installed in the ship, and a UEP sensor and an electric conductivity meter attached to the bottom of the ship. In the processor, the measured values of the UEP sensor and the electric conductivity meter are used. Obtaining a UEP-induced magnetic field at the magnetic sensor position, subtracting the UEP-induced magnetic field from the output value of the magnetic sensor to obtain a magnetic field based on ship magnetism, and estimating ship magnetism from the magnetic field based on the ship magnetism And a step of performing.

  It should be noted that any combination of the above-described constituent elements, and those obtained by converting the expression of the present invention between methods and systems are also effective as aspects of the present invention.

  According to the hull magnetism estimation apparatus and method according to the present invention, it is possible to obtain information on hull magnetism that is indispensable for determining a demagnetizing coil applied current value that is required when demagnetizing hull magnetism by a degaussing coil.

Explanatory drawing which shows embodiment of the ship body magnetic estimation apparatus and method which concern on this invention. Explanatory drawing which shows typically about ship body magnetism, a UEP cause magnetic field, and a demagnetizing coil. Explanatory drawing which looked from right behind the hull which shows typically that the magnetic field by a hull magnetism, and a UEP cause magnetic field overlap in a ship.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or equivalent component, member, process, etc. which are shown by each drawing, and the overlapping description is abbreviate | omitted suitably. In addition, the embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

  FIG. 1 is an embodiment of the present invention, and for example, a set of underwater potential measuring electrodes 1-1 to 1-2 as a UEP sensor and one piece of the bottom of the ship 10 (outer bottom surface of the hull). An electrical conductivity meter 4 capable of measuring the electrical conductivity in water is disposed (attached), electrodes 1-1 to 1-2 are connected via cables 2-1 to 2-2, and electrical conductivity meter 4 is dedicated. It is coupled (connected) to a processor 3 including a computer via a cable 5. In the hull of the ship 10, for example, three-axis magnetic sensors 6-1 to 6-3 that detect magnetic fields in the X, Y, and Z directions, which are three orthogonal axes, are located at the front, rear, and intermediate positions of the ship 10, for example. It is installed (attached), and is coupled to the processor 3 via magnetic information cables 7-1 to 7-3. The processing result of the processor 3 is coupled to the display 9 via the connection cable 8, and the processing result is displayed on the display 9. The processing result of the processor 3 is recorded by the recording device 15.

The processor 3 detects the potential difference V between the electrodes 1-1 and 1-2, and calculates the UEP current value I = VS flowing under the ship bottom underwater from the result and the measured value S from the electric conductivity meter 4. For example, it is assumed that a linear current flows between the electrodes 1-1 and 1-2 according to the Bio-Saval formula (the following formula (1)), and the distance from the current I to the magnetic sensor is R and the distance R the permeability mu, when placed circular constant and [pi, estimates the UEP due field B _U in each magnetic sensor position of the (step 1).
B _U = μI / (4πR) (1)

The processing unit 3 detects a potential difference V of the electrodes 1-1 and 1-2, the measurement value S from the result and the electrical conductivity meter 4, to estimate the UEP due magnetic field B _U example by a finite element method The method is fine.

Further, processor 3 detects a potential difference V of the electrodes 1-1 and 1-2, the measurement value S from the result and the electrical conductivity meter 4, to estimate the UEP due magnetic field B _U by e.g. BEM The method is fine.

The processor 3 is, net of UEP due field _{B U} from the magnetic field detected values _{B T} of the magnetic sensors 6-1 to 6-3 to obtain the magnetic field _{B S} based on the hull magnetic (Step 2). Based on the magnetic field B _S based on the hull magnetism, the hull magnetic quantity is calculated according to, for example, Patent Document 1 (step 3). That is, the processor 3 sequentially executes steps 1, 2, and 3. The display 9 displays the output value from the processor 3 (the ship magnetism estimation result). Further, the output value from the processor 3 (hull magnetism estimation result) is recorded by the recording device 15.

  According to the present embodiment, it is possible to easily and quickly estimate the hull magnetism that is indispensable for determining the demagnetizing coil applied current value that is required when the hull magnetism is demagnetized by the degaussing coil. Further, the ship magnetism can be estimated even when the ship 10 is anchored or navigating at an arbitrary place, and the place where the ship magnetism is estimated is not limited to a specific place.

  The present invention has been described above by taking the embodiment as an example. However, it is understood by those skilled in the art that various modifications can be made to each component and each processing process of the embodiment within the scope of the claims. By the way. Hereinafter, modifications will be described.

  In the above embodiment, the case where the number of magnetic sensors arranged on the hull is exemplified, but the number is not limited to three, and the number is arbitrary.

1-1, 1-2 Underwater potential measurement electrodes 2-1, 2-2, 5, 7-1, 7-2, 7-3, 8 Cable 3 Processor 4 Conductivity meter 6, 6-1, 6 -2, 6-3 Magnetic sensor 9 Display 10 Ship 15 Recording device 20 Hull 21 Schematic hull magnetism 22-1, 22-2 Demagnetizing coil 23 Propulsion device

One embodiment of the present invention is a ship body magnetic estimator. This hull magnetism estimation device includes a magnetic sensor and a processor installed in the ship, a submerged potential measuring electrode and an electric conductivity meter that form a set attached to the bottom of the ship,
The processor determines a UEP due field at the magnetic sensor position from the electric conductivity measurement of the potential difference and the electrical conductivity meter between water potential measuring electrodes forming the pair, the UEP from the output value of the magnetic sensor The magnetic field based on the hull magnetism is obtained by subtracting the induced magnetic field, and the hull magnetism is estimated from the magnetic field based on the hull magnetism.

Another embodiment of the present invention is a hull magnetic field estimation method. This hull magnetism estimation method uses a magnetic sensor and a processor installed in the ship, a submerged potential measuring electrode and an electric conductivity meter that are attached to the bottom of the ship,
In the processor, determining a UEP due field at the magnetic sensor position from the electric conductivity measurement of the potential difference and the electrical conductivity meter between water potential measuring electrodes forming the pair, from the output value of the magnetic sensor The steps of obtaining a magnetic field based on hull magnetism by subtracting the UEP-induced magnetic field and estimating a hull magnetism from the magnetic field based on the hull magnetism are performed.

Claims (4)

A magnetic sensor and a processor installed in the ship, a UEP sensor and an electric conductivity meter attached to the bottom of the ship,
The processor obtains a UEP-induced magnetic field at the magnetic sensor position from the measured values of the UEP sensor and an electric conductivity meter, and subtracts the UEP-induced magnetic field from the output value of the magnetic sensor to obtain a magnetic field based on ship magnetism. A hull magnetism estimation apparatus characterized by obtaining hull magnetism from a magnetic field based on the hull magnetism.   The hull magnetism estimation apparatus according to claim 1, further comprising a display for displaying the hull magnetism estimation result.   The hull magnetism estimation device according to claim 1, further comprising a recording device that records the estimation result of the hull magnetism. Using a magnetic sensor and a processor installed in the ship, a UEP sensor and an electric conductivity meter attached to the ship bottom,
In the processor, a step of obtaining a UEP-induced magnetic field at the magnetic sensor position from measured values of the UEP sensor and an electric conductivity meter, and subtracting the UEP-induced magnetic field from an output value of the magnetic sensor, based on ship magnetism. A hull magnetism estimation method comprising: obtaining a magnetic field; and estimating a hull magnetism from a magnetic field based on the hull magnetism.

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