JPS6173013A - Deviation correcting method of terrestrial magnetism azimuth sensor - Google Patents

Abstract

PURPOSE:To obtain a small-sized, inexpensive device which easily corrects deviation and a horizontal magnetic field with high accuracy by measuring plural reference directions and direction differences of the indicated azimuth of a terrestrial magnetic sensor from the azimuths, and calculating the sum of a geographic magnetic deviation value at a measurement point and its azimuth difference. CONSTITUTION:When deviation is corrected without considering geographic magnetic deviation, a deviation calculation contact is selected with a function switch 5 and a contact of, for example, the north is selected with an eight-azimuths selection switch 2. Then the bow of a ship is directed to the north on a map. At this time, a push button switch 6 is pressed to input the output of the terrestrial magnetic sensor 1 to the CPU of an arithmetic part 7, and the difference from a reference direction is calculated and stored in a memory. When the calculating operation is carried out for all eight azimuths, the arithmetic pat 7 generates a corrected value table of 0-360 deg. on the basis of deviation data. When the north pole is selected as are reference azi muth, a zero position contact is selected with the eight-azimuth selection switch 2, and the magnetic deviation value at the point is set by a geographic deviation value setter 3 and the push button is pressed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic compass used on a moving body constructed of a magnetic material, such as a ship or an automobile.

As is well known, a magnetic compass uses a magnet to point in a certain direction using the earth's magnetic field. However, when a magnetic compass is installed onboard a ship, not only the earth's magnetism but also the ship's own magnetism act on it, and as a result, the magnetic compass indicates the direction of the combined magnetic field of the earth's magnetism and the ship's magnetic field. The deviation in the indicated heading caused by the ship's magnetism is called the deviation of the magnetic compass, and the deviation differs for each ship equipped with a magnetic compass. Further, a magnetic compass indicates the direction relative to the horizontal magnetic field of the Earth's magnetism, but the horizontal magnetic field differs from region to region on the earth.

Therefore, if the horizontal magnetic field changes, the direction of the composite magnetic field with the hull magnetism also changes, and therefore the direction indicated by the magnetic compass also changes.

As is clear from the above, in order to know the accurate bearing using the magnetic compass, it is necessary to correct the deviation component due to the hull magnetism and the magnetic deviation value due to the deviation of the horizontal magnetic field from the indicated bearing of the magnetic compass.

(Prior art) Conventionally, as a means of correcting the deviation component due to hull magnetism,
Magnets are placed around the magnetic compass to cancel out the ship's magnetic field. However, since this work requires great skill, the workability of equipping the magnetic compass is very poor.

As a device to solve this drawback, the applicant proposed
We proposed the technology shown in Publication No. 5213. However, since this invention uses a synchronized transmitter/receiver and a potentiometer, the response is poor, and since many variable resistors are used to set correction values, it is not practical, and the numerical setting is complicated.

(Problems to be Solved by the Invention) An object of the present invention is to provide a device that can easily correct errors and horizontal magnetic fields with high precision, and can be made smaller and cheaper.

(Means for Solving the Problem) FIG. 1 is a block diagram schematically showing the configuration of the present invention.

1 is a geomagnetic sensor such as a magnetic compass, which measures, for example, the angle of intersection between the bow and stern line and the geomagnetic direction and outputs it to the calculation unit 7. 2 is an 8-direction selection switch: Atte, N, NE
, E , SE, S , SW, W, NW (7) It has 9 contact points in 8 directions and the O position, and when performing deviation correction, one of the 8 directions and the geographical magnetic deviation value are used. When setting, select the O position contact and output the direction code signal to the calculation section 7. Reference numeral 3 denotes a geographical deviation value setter, which sets the value of the geographical magnetic deviation, if any, at the measurement point and outputs it to the calculation section 7. Reference numeral 4 denotes a direction indicator, which displays the corrected direction with arrows or digital values. 5 is a function switch for selecting normal direction measurement or error calculation. Reference numeral 6 denotes a pushbutton switch, which instructs the calculation unit 7 to perform various operations.

Reference numeral 7 denotes an arithmetic unit which calculates the difference output between the output of the geomagnetic sensor and the reference direction and creates a correction table, the detailed operation of which will be explained next.

(Function) Deviation correction without considering geographic magnetic deviation first (magnetic north reference)
The effect in the case of is explained.

First, select the error calculation contact using the function switch 5 shown in FIG. Next, use the 8-direction selection switch 2 to select the north contact point if one of the 8 directions is north, then turn the ship to align the bow with north on the map. In reality, this is done while referring to the target on land. At this time, the pushbutton switch 6 is pressed to input the measurement output from the geomagnetic sensor 1 into the calculation unit 7. Arithmetic unit 7
As shown in FIG. 3, the central processing unit (CPU) calculates the difference between the output direction of the geomagnetic sensor l and the reference direction and stores it in a memory address corresponding to the set direction. next,
The operator controls the 8-direction selection switch 2 to select the next direction, for example, NE, turns the bow, and presses the pushbutton switch 6 to head toward the NE direction. Then, the deviation value in the reference direction NE is calculated by the same operation as described above and stored in a predetermined memory address. When these calculation operations are completed for all eight directions, the calculation unit 7 calculates the deviation from O to 360 based on the deviation data of the eight directions.
Create a deviation value (corrected value) table in the degree direction. The above flowchart is shown in the left half of FIG.

By completing this correction table, Il.
The l constant allows for corrected and accurate measurements of deviations.

On the other hand, if the north pole rather than the magnetic north is selected as the reference direction, geographic deviations must be taken into account as described above. In other words, the deviation from the reference direction obtained at each point in the eight directions includes the geographic magnetic deviation at that measurement point, so the resulting azimuth value of the magnetic compass also includes the geographic magnetic deviation. become. In other words, the individual values at the points where the difference has been corrected are used as unbiased constants. In other words, even if the ship carrying the magnetic compass changes its geographical magnetic deviation at another point as it moves, the error added at the deviation correction point will still be included. show. Therefore, in order to obtain an accurate orientation using the North Pole reference, it is necessary to subtract the geographical magnetic deviation of the measured value from each data.For this reason, the present invention is implemented as follows. In Figure 1, when measuring the direction based on the North Pole, first select the O position contact with the 8 direction selection switch 2, set the magnetic deviation value of that point with the geographic deviation value setting device 3, and press the push button. . If this is done, the calculation section 7 will add a step of subtracting the geographical deviation value from the correction value in each direction, as shown in the third block in FIG.

(Effects) As described above, according to the present invention, there is an advantage that correction data for azimuth from 0 to 380 degrees can be obtained by simply pressing a button, and furthermore, the geographical deviation value of the deviation correction point can be obtained in advance. Since it is adjusted, it has the advantage that when measuring direction, it is possible to accurately measure direction based on the North Pole simply by setting the geographical deviation value of that point.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a flowchart of its calculation section, and FIG. 3 is a detailed flowchart of the CPU processing of FIG. 2. 5W, I IIin Fig. 3

Claims (1)

[Claims] A step of measuring the azimuth difference between a plurality of reference azimuths and the azimuth indicated by the geomagnetic sensor in the azimuths, a step of calculating the sum of the geographical magnetic deviation value of the point where the azimuth difference is measured and the above-mentioned azimuth difference, A method for correcting deviation of a geomagnetic azimuth sensor, characterized in that a sum corresponding to a fine azimuth is further calculated based on the sum corresponding to a plurality of reference azimuths to obtain a deviation correction value corresponding to the fine azimuth.