JPS60135814A - Azimuth detecting apparatus - Google Patents

Abstract

PURPOSE:To make it possible to detect an azimuth angle with good accurcy by automatically detecting the change in residual magnetism disable to be foreknown during movement to correct the azimuth angle, by simple constitution such that two magnetic detection means for detecting the magnitude and direction of a magnetic field vector are used. CONSTITUTION:The difference of the amounts of two magnetic field vectors detected by two magnetic detection means 1, 2 is calculated by a subtraction means 3 and the detection value of either one of magnetic field detection means on the basis of said difference by a correction means 14 to detect an azimuth with good accuracy. In this apparatus, for example, magnetic sensors 1, 2 are arranged on the roof of a car in parallel in a vertical direction and the detected signal is converted to a digital signal which is, in turn, outputted to an operator 10. The operator 10 has functions of the vector subtraction means 3 and the correction means 4, and performs vector subtraction and correction operation on the basis of the digital signal to calculate the advance direction of a vehicle. The corrected advance azimuth angle is transmitted to a display apparatus 6 through an interface 11.

Description

[Detailed Description of the Invention] (Technical Field) (Prior Art) Conventionally, this type of direction detection device includes a direction magnet sensor,
Alternatively, a magnetic compass using a fluxgate type magnetic sensor is known. However, many of the parts that make up moving bodies such as vehicles and ships are magnetic, and therefore they are magnetized and retain residual magnetism during manufacturing processes such as sheet metal or welding, or when they pass through a magnetic field during movement. This residual magnetism is detected by a magnetic azimuth meter installed on the moving body as a magnetic amount combined with earth's magnetism, resulting in a large error in the detected azimuth.

Conventionally, to detect this residual magnetism, the moving object is rotated once, and the residual magnetism is detected as OP from the locus of the detection value E of the 7-lux gate type magnetic sensor, as shown in Fig. 1. . The obtained OF is subtracted from the detected value E to obtain the horizontal component Hs of the earth's magnetism, and the current azimuth angle 0 is calculated from the horizontal component Hs of the earth's magnetism. Here, u shown in Figure 1
, v represent orthogonal components of the magnetic vector detected by the magnetic detection means. r represents the azimuth before correction.

However, this amount of residual magnetism is not always constant and may change when passing through a relatively strong magnetic field such as near a DC overhead wire. Therefore, after the amount of residual magnetism changes, the corrected azimuth angle becomes θ" as shown in Figure 2, which causes an error. In addition, as a solution to this drawback, three magnetic sensors were used. arranged vertically,
There is a method of performing correction based on the three detected values, but this method has the drawback that the configuration and correction calculations are double-tracked.

〔the purpose〕

An object of the present invention is to provide an azimuth detection device that can automatically detect unpredictable changes in residual magnetism during movement with a relatively simple configuration and correct the azimuth angle.

[Structure of the invention]

According to the present invention, the magnetic detection means for detecting the direction and magnitude of a magnetic field is provided, and the difference between two magnetic field vector quantities detected by the magnetic detection means is calculated by the vector subtraction means. The correction means corrects the detected value of one of the magnetic field detection means based on the difference in the amount of magnetic field vectors, thereby obtaining an orientation detection device configured to detect the orientation with high accuracy.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 3, the embodiment of the present invention has magnetic detection means 1 and 2 for detecting the direction and magnitude of a magnetic field, and two magnetic fields detected by the magnetic detection means 1 and 2. The difference in the amount of magnetic field vectors is requested by the vector subtraction means 3, and the detected value of either one of the magnetic field detection means is corrected by the correction means 4 based on the difference in the amount of magnetic field vectors, so that the direction can be detected with high accuracy. It is composed of

FIG. 4 shows an example of the overall arrangement of the orientation detecting device according to the present invention mounted on an automobile. Magnetic detection means 1, 2
are arranged on the roof of the vehicle body 7 in a direction perpendicular to the roof, and the direction detection device main body 52 and the display device 6 are arranged inside the vehicle.

According to FIG. 5, the orientation detecting device of this embodiment has a first magnetic detecting means 1 and a second magnetic detecting means 2 of a flux gate type that is resistant to vibration and can easily obtain an electrical output proportional to the magnetic field. Uses a magnetic sensor. The magnetic detection means 1.2 both have the same performance and have the function of detecting the magnitude and direction of the magnetic field vector and outputting it to the multiplexer 8 as an analog electrical signal. The multiplexer 8 is a magnetic detection means l.

It has a function of selecting an analog signal to be outputted from 2 and outputting the analog signal to the A/D converter 9. A/D
The converter 9 has a function of converting the analog signal selected by the multiplexer 8 into a digital signal and outputting the digital signal to the arithmetic unit 10. The arithmetic unit 10 has a vector subtraction function by the vector subtraction means 3 and a correction calculation function by the correction means 4, and performs vector subtraction and correction calculations based on the digital signal sent from the A/D converter 9. Determine the vehicle's heading angle. Further, it is an electronic circuit mainly composed of a microprocessor that has a function of transmitting the corrected traveling azimuth of the vehicle to the interface 11. The interface 11 has a function of transmitting the vehicle traveling azimuth outputted by the calculator 1O to the display unit 6, and the display device 6 has a function of displaying the vehicle traveling azimuth transmitted to the interface 11. has.

6 and 7, a method of correcting the azimuth angle when the azimuth detecting device of the present invention is installed in a vehicle as shown in FIG. 4 will be explained. As shown in FIG. 6, the horizontal component of the earth's magnetism →' is Hs, and the horizontal component of the magnetic field vector detected by the magnetic detection means 1 and 2 is El.

Et+ The magnetic detection means 1.2 is affected by residual magnetism, and since the magnetic detection means 1 is closer to the vehicle body 7 than the magnetic detection means 2, it is strongly influenced by the residual magnetism.
1 (Jr, l. OP,, OF2 is E1 when the vehicle makes one turn.
It depends on the trajectory of +E2. This is when it will happen.

Also → ← → → → → E, −E2=(OP, 10Hs)−(OP2+Hs)=
o)), -op.

= P, P, ...(3) Therefore, from equation (1) and equation (3), OF, = k
(E, -E, ) ...... (4) Therefore, Hs = E, -UP.

-E+ -k(E+ -E2) ・・・・・・(5)
is established.

Next, when the amount of residual magnetism changes, as shown in FIG. The horizontal component of the magnetic vector E, detected by °2.

From E2, the horizontal component Hs of the earth's magnetism and the azimuth angle θ can be determined by the calculator 10.

FIG. 8 is a flow chart showing the software of the computing unit 10. In step 12, data is input through the magnetic detection means transducer 9. Step 13 determines whether the vehicle has made one turn based on the input data, and if the vehicle has not made one turn, step 12 is repeated again. In step 14, the horizontal component of the magnetic vector received by the residual magnetism of the vehicle body 7 is determined based on the input data in step 12.

Calculate OP. In step 15, a proportionality constant k is calculated based on OFl and OP determined in step 14 according to equation (2). In step 16, similarly to step 12, the outputs E, , E, of the magnetic detection means 1.2 are sent to the multiplexer 8. Data is input through the A/D converter 9. In step 17, input data EI + E in step 16
2 and the proportionality constant k determined in step 15 are substituted into equation (5) to calculate the horizontal component Hs of geomagnetism. In step 18, the vehicle heading angle θ is calculated based on Hs calculated in step 17. In step 19, the vehicle traveling azimuth θ calculated in step 18 is sent to the display device 6 through the intern eight circuit 11, and the vehicle traveling azimuth θ is displayed.

Although the case where the magnetic direction detector of the present invention is installed in a car has been described above, it is clear that this can also be applied to other moving objects such as ships and aircraft.

Further, by using the azimuth detecting device of the present invention in a device that detects the position of a vehicle based on the traveling azimuth angle and travel distance of the vehicle, a highly accurate vehicle position detecting device can be obtained.

As explained above, according to the present invention, the magnetic detection means is
With a relatively simple configuration in which only two magnets are used, it is possible to automatically correct the influence of the residual magnetism of the magnetic body near the magnetic detection means, and it has the effect that the orientation can be detected with high accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows orientation correction according to a conventional method. Figure 2 shows the locus of the compass output when the residual magnetism changes. Third
The figure is a block diagram showing the configuration of the present invention. FIG. 4 shows the overall arrangement of an embodiment of the orientation detecting device of the present invention. FIG. 5 is a block diagram showing the configuration of the embodiment shown in FIG. 4. FIGS. 6 and 7 are explanatory diagrams of the azimuth angle correction method. FIG. 8 is a flow chart showing the software of the computing unit 10. l...Magnetic detection means 1.2...Magnetic detection means 23...Vector subtraction means, 4...
...Correction means, 5... Orientation detection device main body, 6.
... Display device, 7 ... Car body, 8 ...
...Multiplexer, 9...A/D converter, l
O... Arithmetic unit, 11... Interface. 1st leap. Figure 5

Claims (2)

[Claims] (1) Two magnetic detection means for detecting the magnitude and direction of the magnetic field vector, and a vector subtraction stage for calculating the difference between the two magnetic field vectors detected by each of the two magnetic detection means. , correction means for correcting either one of the two magnetic field vectors detected by each of the two magnetic detection means based on the difference between the magnetic field vectors calculated by the vector subtraction means. A magnetic direction detection device characterized by: (2) The correction means subtracts a vector obtained by multiplying the magnetic field vector calculated by the vector subtraction means by a coefficient from either one of the two magnetic field vectors detected by each of the two magnetic detection means. A magnetic direction detecting device according to claim 1, characterized in that the magnetic direction detecting device performs calculations such as: