JP2007101354A - Azimuth measuring device and system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an azimuth measuring device and an azimuth measuring system capable of quickly acquiring the remaining magnetism value of a magnetic sensor and exactly measuring the azimuth of bow direction. <P>SOLUTION: A magnetic sensor compass 3 calculates the bow azimuth ψm, based on a detected magnetism true value obtained by subtracting a remaining magnetism value from the detected magnetism value detected by a 3-axis magnetic sensor 38. The remaining magnetism value is calculated from the detected magnetism value detected by the 3-axis magnetic sensor 38 and standard terrestrial magnetism gained, based on terrestrial magnetism data stored in a terrestrial magnetism data memory 22. A satellite measuring compass 2 calculates a bow azimuth ψs from signals received with satellite receivers 34a and 34b. A selector 10 inputs the bow azimuth ψs in a bow azimuth display 12 as a bow azimuth ψ when the receiving status of the satellite receiver 34a is good, and inputs the bow azimuth ψm as the bow azimuth ψ when the receiving status of the satellite receiver 34a is no good. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus and a system for measuring the heading direction of a ship based on an output value of a magnetic sensor.

  Magnetic sensors that detect geomagnetism are widely used as means for measuring the heading direction of a ship. The magnetic sensor is fixed to the ship, detects magnetism in three orthogonal directions, and outputs the value. Since the direction of the magnetic field lines of the geomagnetism is known, it is possible to know the heading direction of the ship based on the detected magnetic values in the three-axis directions.

  In general, the magnetism detection value indicated by the magnetic sensor includes a residual magnetism value indicated when the magnetism value to be detected is zero. Therefore, it is necessary to measure the residual magnetic value in advance and set the value obtained by subtracting the residual magnetic value from the magnetism detection value as the true value of the magnetic value.

  In order to measure the remanent magnetic value, conventionally, the detected value of the geomagnetism in the biaxial direction in the horizontal plane is acquired while rotating the ship on which the magnetic sensor is fixed on a calm water surface. Specifically, for example, an x-axis defined in the bow direction and a y-axis perpendicular to the x-axis are defined on the deck surface of the ship 100 as shown in FIG. A locus of points on the Hx-Hy plane expressed by the value Hx and the detected value Hy in the y-axis direction is drawn. Since the locus is a circle centered on the coordinate point indicating the remanent magnetic value as shown in FIG. 4, the remanent magnetic values ΔHx and ΔHy included in the detected values Hx and Hy are obtained by obtaining the center coordinates of the circle. Can be obtained.

  However, in such a configuration, since it is necessary to actually rotate the ship on the water surface, it takes a lot of time to acquire the residual magnetic value. In addition, the residual magnetic value in the direction of the axis perpendicular to the deck surface among the three axis directions cannot be acquired, and the influence of the residual magnetic value in the direction of the axis perpendicular to the deck surface is removed when measuring the heading direction. Since this is not possible, there is a problem that an error is included in the heading direction measured when the ship is tilted.

  The present invention has been made to solve such a problem, and is capable of quickly acquiring a remanent magnetic value of a magnetic sensor and accurately measuring a heading direction heading and a heading. Provide a measurement system.

  An azimuth measuring apparatus according to the present invention is based on a reference magnetic information acquisition unit that acquires reference magnetic information that is information relating to a reference value of geomagnetism, a magnetic sensor that detects geomagnetism and outputs the value, and the reference magnetic information A correction unit for correcting the output value of the magnetic sensor, and measuring the heading direction of the ship based on the output value of the magnetic sensor corrected by the correction unit.

  In the azimuth measuring apparatus according to the present invention, the correction unit calculates a correction value for the output value of the magnetic sensor based on the reference magnetic information and the output value of the magnetic sensor; Correction value storage means for storing the correction value calculated by the correction value calculation means, and configured to correct the output value of the magnetic sensor based on the correction value stored in the correction value storage means. Is preferred.

  In the azimuth measuring apparatus according to the present invention, the reference magnetic information acquisition unit includes a positioning unit that performs positioning based on a signal transmitted from a satellite, and the reference magnetic information is based on a positioning result of the positioning unit. It is preferable to obtain the configuration.

  The azimuth measuring device according to the present invention includes a positioning azimuth measuring device that receives a signal transmitted from a satellite and measures a azimuth in a bow direction of a ship based on the received signal. One of the positioning azimuth measuring devices is selected according to the reception status of the signal transmitted from the satellite at the positioning azimuth measuring device, and the ship is selected by either the selected azimuth measuring device or the positioning azimuth measuring device. It is possible to configure an azimuth measurement system that measures the azimuth in the bow direction.

  According to the present invention, the heading direction of a ship can be measured quickly and accurately.

  FIG. 1 shows the configuration of a heading measurement apparatus 1 according to an embodiment of the present invention. The heading measurement apparatus 1 includes a satellite positioning compass 2, a magnetic sensor compass 3, a selection unit 10, a heading display unit 12, a horizontal conversion unit 14, a direction conversion unit 16, a residual magnetic value calculation unit 18, a geomagnetic data acquisition unit 20, A geomagnetic data storage unit 22, an azimuth reverse conversion unit 24, a horizontal reverse conversion unit 26, an attitude angle detection unit 28, and a smoothing unit 30 are provided.

  The bow direction measuring apparatus 1 is mounted on a ship 100. FIGS. 2A and 2B are views for explaining the definition of the heading direction (hereinafter referred to as the heading direction ψ) of the ship 100 in which the heading measuring apparatus 1 is mounted. The heading ψ is represented by an angle formed by the horizontal component in the bow direction of the ship 100 and the north direction. The heading direction ψ is positive in the direction of rotation from the north direction to the west direction.

  The ship 100 defines a ship coordinate system O (xyz coordinate system) fixed to the ship 100 with a certain point in the ship 100 as an origin O. Further, the origin Or is made the same as the origin O of the ship coordinate system O, and a horizontal coordinate system Or (xr-yr-zr coordinate system) in which the negative direction of the zr axis is the vertical direction and the yr axis is orthogonal to the x axis is defined. . The xy plane with the bow direction of the ship 100 as the x axis is a plane parallel to the deck surface of the ship 100, the yr axis of the horizontal coordinate system Or is the pitch axis, and the x axis of the ship coordinate system O is the roll axis. And The deck surface is defined as being fixed to the ship 100 and is a plane that is horizontal when the ship 100 is on a horizontal water surface. The inclination of the ship 100 with respect to the horizontal plane is represented by a roll angle φ and a pitch angle θ. The pitch angle θ is a rotation angle in which the x axis rotates in the counterclockwise direction in the xr-zr plane with the origin Or as the center, and the roll angle φ is the rotation of the x axis at the pitch angle θ. Further, the rotation angle is positive when the x axis is the rotation axis and the y axis is rotated clockwise as viewed from the positive direction of the x axis.

  FIG. 2B shows the relationship between the horizontal coordinate system Or defining the heading azimuth ψ and the true azimuth coordinate system Oe. In the true azimuth coordinate system Oe (xe-ye-ze coordinate system), the positive direction of the xe axis is the north direction, the negative direction of the ze axis is the vertical direction, and the origin Oe is the same as the origin Or of the horizontal coordinate system Or. The bow direction ψ is defined by an angle formed by the xe axis of the true azimuth coordinate system Oe and the xr axis of the horizontal coordinate system Or, and the direction rotated counterclockwise on the xe-ye plane is positive.

  The bow direction measuring apparatus 1 calculates and displays the bow direction ψ by using either the satellite positioning compass 2 or the magnetic sensor compass 3. Since the satellite positioning compass 2 receives a signal transmitted from a positioning satellite such as a GPS satellite and calculates the heading ψs based on the received signal, it can calculate the heading ψs when the reception condition is not good. Can not. For example, the reception situation often deteriorates when the ship 100 is navigating under a bridge, a port with many obstacles, a cove, and the like. Therefore, the heading measuring apparatus 1 is configured to display the heading ψm calculated by the magnetic sensor compass 3 as the heading ψ when the reception status of the signal transmitted from the positioning satellite is not good.

  The satellite positioning compass 2 includes antennas 32a and 32b, satellite receivers 34a and 34b, and a heading calculation unit 36. The antennas 32 a and 32 b are provided at predetermined positions on the ship 100. Satellite receiving units 34a and 34b receive signals transmitted from positioning satellites such as GPS satellites via antennas 32a and 32b, respectively. The satellite receivers 34a and 34b acquire the position coordinates in a coordinate system (hereinafter referred to as an absolute coordinate system) with the center of the earth of the antennas 32a and 32b as the origin, and input them to the heading calculation unit 36. For acquisition of the position coordinates, a single positioning method based on the pseudorange and the time error correction amount, an interference positioning method, or the like can be used. The heading calculation unit 36 calculates the heading ψs based on the position coordinates of the antennas 32 a and 32 b in the absolute coordinate system, and inputs them to the selection unit 10, the direction conversion unit 16, and the direction reverse conversion unit 24.

  The satellite receiver 34a has a deteriorated reception status such as the electric field intensity of the signal transmitted from the positioning satellite is less than a predetermined value, or the bit error rate of the demodulated digital signal exceeds a predetermined value. In some cases, the reception disable signal is input to the selection unit 10, the residual magnetic value storage unit 42, and the standard geomagnetic storage unit 48. The satellite reception unit 34b inputs the position coordinates in the absolute coordinate system of the antenna 32b and the current year extracted from the received signal to the geomagnetic data acquisition unit 20.

  Instead of the configuration in which the satellite reception unit 34 a inputs the reception incapability signal to the selection unit 10, the satellite reception unit 34 b can also have a configuration in which the reception inability signal is input to the selection unit 10. Further, instead of the satellite receiving unit 34b inputting the position coordinates of the antenna 32b and the current year in the geomagnetic data acquisition unit 20, the satellite reception unit 34a receives the position coordinates of the antenna 32a and the current year in the geomagnetic data acquisition unit 20. It can also be set as the structure input into. Further, in addition to the configuration in which the bow direction ψs is acquired by the satellite receivers 34a and 34b, the configuration in which the bow direction ψs is acquired by applying a satellite receiver that measures the moving speed and direction of the ship 100 may be adopted. it can.

  The magnetic sensor compass 3 includes a three-axis magnetic sensor 38, a residual magnetic value subtraction unit 40, a residual magnetic value storage unit 42, a horizontal conversion unit 44, a heading calculation unit 46, and a standard geomagnetic storage unit 48.

  The triaxial magnetic sensor 38 is fixed to the deck surface of the ship 100. The three-axis magnetic sensor 38 detects magnetic values in the x-axis direction, the y-axis direction, and the z-axis direction, and inputs the detected magnetic values (Hx, Hy, Hz) to the residual magnetic value subtraction unit 40 and the horizontal conversion unit 14. To do. The detected magnetic values Hx, Hy, and Hz are a component of the detected magnetic value in the x-axis direction, a component in the y-axis direction, and a component in the z-axis direction, respectively.

  The residual magnetic value storage unit 42 stores the residual magnetic values (ΔHx, ΔHy, ΔHz) acquired and input in advance. The process for acquiring the residual magnetic value will be described later.

  The residual magnetic value subtraction unit 40 reads the residual magnetic value (ΔHx, ΔHy, ΔHz) from the residual magnetic value storage unit 42, and calculates the residual magnetic value (ΔHx, ΔHy, ΔHz) from the detected magnetic value (Hx, Hy, Hz). The value is subtracted and input to the horizontal conversion unit 44 as a magnetic true value (Tx, Ty, Tz).

  The horizontal conversion unit 44 acquires the roll angle φ and the pitch angle θ of the boat 100 from the attitude angle detection unit 28. Then, based on the roll angle φ and the pitch angle θ, the magnetic true value (Tx, Ty, Tz) is converted into a horizontal coordinate system magnetic true value (Txr, Tyr, Tzr) converted into a value in the horizontal coordinate system Or, Input to the heading calculation unit 46. The attitude angle detection unit 28 is preferably configured by a biaxial acceleration sensor (not shown) fixed to the deck surface of the ship 100. In this case, the two-axis acceleration sensor detects the acceleration in the x-axis direction and the y-axis direction, and the roll angle φ and the pitch angle θ are calculated based on the detected values.

  The standard geomagnetism storage unit 48 is a standard geomagnetism value (Hxe0, Hxe0, which is acquired in advance based on geomagnetism data that is data related to an international standard geomagnetic reference field (IGRF) that is available to the public. Hye0, Hze0) is stored. Standard geomagnetism values (Hxe0, Hye0, Hze0) indicate values in the true azimuth coordinate system Oe defined in FIG. The process for acquiring this value will be described later.

  The heading calculation unit 46 calculates the heading ψm based on the standard geomagnetism values (Hxe0, Hye0, Hze0) read from the standard geomagnetic storage unit 48 and the horizontal true coordinate system magnetic values (Txr, Tyr, Tzr). calculate. Specifically, the bow direction ψm is calculated as follows. (1) The heading calculation unit 46 calculates a horizontal coordinate system geomagnetic direction ψ0 that is an angle of the horizontal component vector (Txr, Tyr) of the horizontal coordinate system magnetic true value (Txr, Tyr, Tzr) with respect to the xr axis. The horizontal coordinate system geomagnetic direction ψ 0 is positive in the clockwise direction around the origin Or in the xr-yr plane. (2) The heading calculation unit 46 is an angle from the north direction to the east direction of the horizontal component of geomagnetism based on the horizontal component vector (Hxe0, Hye0) of standard geomagnetism values (Hxe0, Hye0, Hze0). The deflection angle D is calculated. That is, the deflection angle D is an angle of the horizontal component of geomagnetism with respect to the xe axis, with the clockwise direction centering on the origin Oe in the xe-ye plane being positive. (3) The heading calculation unit 46 calculates the heading ψm by subtracting the deviation angle D from the horizontal coordinate system geomagnetic direction ψ0. The heading ψm calculated in this way indicates an azimuth in which the north direction is 0 ° and the rotation direction from the north direction toward the west is positive. That is, as shown in FIG. 3, from the horizontal coordinate system geomagnetic direction ψ0, which is an angle with respect to the xr axis of the horizontal component vector (Txr, Tyr) with the clockwise direction centered on the origin Or as the center in the xr-yr plane, By subtracting the declination D having the same rotational direction as the positive direction, the heading ψm with the counterclockwise direction centered on the origin Oe on the xe-ye plane is obtained.

  The selection unit 10 acquires the heading azimuth ψm from the magnetic sensor compass 3 and inputs it to the heading azimuth display unit 12 as the heading azimuth ψ when a signal that cannot be received from the satellite receiving unit 34 a of the satellite positioning compass 2 is input. Further, when no signal is not received from the satellite receiver 34a of the satellite positioning compass 2, the heading azimuth ψs is acquired from the satellite positioning compass 2 and input to the bow azimuth display unit 12 as the bow azimuth ψ. The heading display unit 12 displays the heading ψ input from the selection unit 10. As the heading display unit 12, it is preferable to apply a display such as a cathode ray tube display or a liquid crystal display.

  Next, a process in which the bow direction measuring apparatus 1 acquires a residual magnetic value and stores it in the residual magnetic value storage unit 42 will be described.

  The horizontal conversion unit 14 acquires the roll angle φ and the pitch angle θ of the ship 100 from the attitude angle detection unit 28. Then, based on the roll angle φ and the pitch angle θ, the detected magnetic value (Hx, Hy, Hz) input from the triaxial magnetic sensor 38 is converted into a value in the horizontal coordinate system Or (horizontal coordinate system detected magnetic value ( Hxr, Hyr, Hzr) and input to the azimuth conversion unit 16.

  The azimuth conversion unit 16 converts the horizontal coordinate system detected magnetic value (Hxr, Hyr, Hzr) into a value in the true azimuth coordinate system Oe based on the bow azimuth ψs input from the bow azimuth calculation unit 36. The system detection magnetic value (Hxe, Hye, Hze) is converted and input to the residual magnetic value calculation unit 18.

  On the other hand, the geomagnetic data acquisition unit 20 refers to the geomagnetic data stored in the geomagnetic data storage unit 22 based on the position coordinates of the antenna 32b input from the satellite reception unit 34b, and determines the geomagnetic data at the position coordinates of the antenna 32b. The value is input as a standard geomagnetism value (Hxe0, Hye0, Hze0) to the residual magnetic value calculation unit 18 and the standard geomagnetism storage unit 48.

  Here, it is preferable to apply an international standard geomagnetic field (IGRF) or the like as the geomagnetic data. According to the IGRF, by designating the current year and the position coordinate in the absolute coordinate system, the value of geomagnetism at the position coordinate can be acquired as the value in the true orientation coordinate system Oe. The geomagnetic data storage unit 22 stores the latest IGRF.

  The residual magnetic value calculation unit 18 subtracts the standard geomagnetism values (Hxe0, Hye0, Hze0) from the true magnetic coordinate system detection magnetic values (Hxe, Hye, Hze) to obtain the true magnetic coordinate system residual magnetic values (ΔHxe, ΔHye, ΔHze) is calculated and input to the azimuth reverse conversion unit 24.

  The azimuth inverse conversion unit 24 calculates the true azimuth coordinate system residual magnetic values (ΔHxe, ΔHye, ΔHze) in the horizontal coordinate system Or based on the bow azimuth φs input from the bow azimuth calculation unit 36 of the satellite positioning compass 2. The horizontal coordinate system residual magnetic values (ΔHxr, ΔHyr, ΔHzr) converted to are converted into the horizontal inverse conversion unit 26.

  The horizontal inverse conversion unit 26 acquires the roll angle φ and the pitch angle θ of the ship 100 from the attitude angle detection unit 28. Based on the roll angle φ and the pitch angle θ, the measured residual magnetic value obtained by converting the horizontal coordinate system residual magnetic values (ΔHxr, ΔHyr, ΔHzr) input from the azimuth reverse conversion unit 24 into values in the ship coordinate system O. It is converted into (Δhx, Δhy, Δhz) and input to the smoothing unit 30. The smoothing unit 30 averages time fluctuations of the actually measured residual magnetic values (Δhx, Δhy, Δhz), and inputs the averaged residual magnetic values (ΔHx, ΔHy, ΔHz) to the residual magnetic value storage unit 42 of the magnetic sensor compass 3.

  The residual magnetic value storage unit 42 receives new residual magnetic values (ΔHx, ΔHy, ΔHz), and updates and stores the values when no reception disable signal is input. And when the reception impossible signal is inputted, the residual magnetic values (ΔHx, ΔHy, ΔHz) inputted immediately before the reception impossible signal is inputted are held.

  Similarly, the standard geomagnetism storage unit 48 receives a new standard geomagnetism value (Hxe0, Hye0, Hze0) and updates and stores the value when no signal is not received. And while the reception impossible signal is input, the standard geomagnetism values (Hxe0, Hye0, Hze0) input immediately before the reception disabled signal is input are held.

  With such a configuration of the heading measurement apparatus 1 and the processing executed by the heading measurement apparatus 1, the residual magnetic value of the three-axis magnetic sensor 38 can be acquired quickly and accurately.

  Further, the residual magnetic value storage unit 42 and the standard geomagnetic storage unit 48 hold the value input immediately before the reception impossible signal is input while the reception disabled signal is input. When the magnetic sensor compass 3 calculates the heading ψm when the reception status is not good, a value acquired while the reception status is good is used. As a result, when the reception status at the satellite receiving unit 34b is good, the bow direction ψs calculated by the satellite positioning compass 2 is displayed on the bow direction display unit 12 as the bow direction ψ, and the reception status at the satellite reception unit 34b is displayed. When it is not good, the heading direction ψm calculated by the magnetic sensor compass 3 can be displayed on the heading direction display unit 12 as the heading direction ψm.

It is a figure which shows the structure of the bow direction measuring apparatus which concerns on embodiment of this invention. It is a figure which shows the relationship between the ship coordinate system O and the horizontal coordinate system Or. It is a figure which shows the relationship between horizontal coordinate system Or and true azimuth | direction coordinate system Oe. It is a figure which shows the relationship between horizontal coordinate system geomagnetic azimuth | direction (psi) 0, declination D, and bow direction (psi) m. It is a figure which shows the locus | trajectory on the Hx-Hy plane of the point determined with the detected value Hx of the x-axis direction and the detected value Hy of the y-axis direction drawn with rotation of a ship.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bow direction measuring device, 2 Satellite positioning compass, 3 Magnetic sensor compass, 10 Selection part, 12 Bow direction display part, 14, 44 Horizontal conversion part, 16 Direction conversion part, 18 Residual magnetic value calculation part, 20 Geomagnetic data acquisition part , 22 Geomagnetic data storage unit, 24 azimuth reverse conversion unit, 26 horizontal reverse conversion unit, 28 attitude angle detection unit, 30 smoothing unit, 32a, 32b antenna, 34a, 34b satellite reception unit, 36, 46 bow direction calculation unit, 38 3-axis magnetic sensor, 40 residual magnetic value subtraction unit, 42 residual magnetic value storage unit, 48 standard geomagnetic storage unit, 100 ship.

Claims (4)

A reference magnetic information acquisition unit that acquires reference magnetic information that is information relating to a reference value of geomagnetism;
A magnetic sensor that detects geomagnetism and outputs the value,
A correction unit that corrects an output value of the magnetic sensor based on the reference magnetic information;
With
An azimuth measuring device for measuring the azimuth of a bow direction of a ship based on an output value of a magnetic sensor corrected by the correction unit. The azimuth measuring apparatus according to claim 1,
The correction unit is
Correction value calculation means for calculating a correction value for the output value of the magnetic sensor based on the reference magnetic information and the output value of the magnetic sensor;
Correction value storage means for storing the correction value calculated by the correction value calculation means;
With
An azimuth measuring apparatus for correcting an output value of the magnetic sensor based on a correction value stored in the correction value storage means. The azimuth measuring apparatus according to claim 1 or 2,
The reference magnetic information acquisition unit
It has a positioning unit that performs positioning based on signals transmitted from satellites,
The azimuth measuring apparatus characterized in that the reference magnetic information is acquired based on a positioning result of the positioning unit. An orientation measuring device according to claim 1;
A positioning direction measuring device that receives a signal transmitted from a satellite and measures the heading direction of a ship based on the received signal;
With
Either the azimuth measuring device or the positioning azimuth measuring device is selected according to the reception status at the positioning azimuth measuring device of the signal transmitted from the satellite, and the selected azimuth measuring device or the positioning azimuth measuring device is selected. An azimuth measuring system for measuring the azimuth of the bow direction of a ship by any of the above.

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