JPH0319927B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a direction detection device that generates a direction signal corresponding to the traveling direction of a moving object, such as a vehicle, based on a signal from a direction detection section.

[Prior art]

In conventional direction detecting devices, distortion of the earth's magnetic field caused by residual magnetism of a vehicle is corrected by, for example, an externally attached correction magnet.

[Problem that the invention seeks to solve]

In this conventional configuration, it is necessary to consider various aspects such as the position, number, and strength of the correction magnets installed outside the frame in order to cancel the distortion of the earth's magnetic field caused by the vehicle's residual magnetism, etc., and the correction is complicated. Furthermore, since the geomagnetic distortion characteristics differ from vehicle to vehicle, different corrections are required for each vehicle. Furthermore, the signal itself from the direction detection unit may be distorted, making it impossible to accurately detect the direction of the earth's magnetic field.

The present invention has been developed in view of the above problems, and it is possible to easily maintain accurate orientation of a moving object at all times by automatically correcting the amount of geomagnetic distortion without requiring complicated correction operations by the occupants of the moving object. The purpose is to enable detection.

[Means for solving problems]

Therefore, in the present invention, as shown in FIG. 6, a direction detecting section 1 is attached to a moving body and detects the direction of the earth's magnetic field using two orthogonal components, and an electric signal of two orthogonal components from the direction detecting section is used. In a direction detection device having a calculation unit 2 that calculates a direction and generates a direction signal, the calculation unit is configured to adjust one of the two orthogonal electric signals from the direction detection unit to a predetermined value. a determining means 2A that automatically determines whether or not they are equal at predetermined intervals; and a predetermined reference value, and a distortion amount calculation storage means 2B that automatically calculates and stores the amount of geomagnetic distortion with respect to the other value; It is said to be equipped with a distortion amount correction means 2C that automatically corrects the amount of distortion based on the amount of geomagnetic distortion stored in the calculation storage means, and an azimuth calculation means 2D that calculates the azimuth based on the corrected two-component electrical signals that are orthogonal to each other. Adopt technical measures.

[Effect]

In the present invention, when one of the orthogonal two-component electric signals becomes equal to a predetermined value, the amount of geomagnetic distortion of the other value becomes equal to a predetermined reference value (for example, a vector of orthogonal two-component electric signals). Focusing on the fact that there is a specific relationship with the radius R of the circle of the trajectory, the other value is compared with the reference value, the distortion amount is repeatedly updated, and the accurate geomagnetic distortion amount is calculated. Then, the direction is calculated based on the electrical signal corrected by this amount of distortion.

〔Example〕

The present invention will be described below with reference to embodiments shown in the drawings. FIG. 1 is an electrical wiring diagram showing one embodiment of the present invention, in which the direction detection sensor 10 has a magnetic core 1c made of ferromagnetic material.
An excitation winding 1D is wound thereon, and output windings 1A and 1B are wound orthogonally to each other. 1
Reference numeral 1 denotes an oscillation circuit which outputs a rectangular wave signal A (FIG. 2 1) in order to excite the excitation winding 1D at a frequency.
The magnetic field inside the magnetic core 1c changes according to the sum of the horizontal component force H of the earth's magnetism applied to the orientation detection sensor 10 and the horizontal component force h of the earth's magnetic distortion, H+h, and an output proportional to the magnetic field inside the magnetic core 1C is output. Winding 1A,
1B, and filters 12A and 12B of the same configuration consisting of a capacitor and a resistor
The component outputs X and Y (Fig. 2, 2 and 3) are obtained.
After amplifying these outputs X and Y using amplifying circuits 13A and 13B, the signal C from the timing circuit 14 is
If the hold circuits 15A and 15B sample and hold (FIG. 2, 4), DC outputs x and y are obtained at points 15a and 15b.

If the horizontal component of the earth's magnetic field H is applied to the output winding 1B at an angle of θ, and the horizontal component of the earth's magnetic strain h is applied at an angle of φ, the outputs x, y is expressed by the following formula.

x=K ₁ (Hsinθ+hsinφ)+K ₂ x y=K ₁ (Hcosθ+hcosφ)+K ₂ y In the above equation, K ₁ is the amplification degree of the direction detection section 1,
K _2x and K _2y are distortions of the orientation detection section 1.

In addition, in the above equation, K ₁・h・sinφ+K _2x and K ₁・h・cosφ+K _2y are the components that the residual magnetism that is magnetized on the vehicle acts on the output winding 1B, so there are Unless the vehicle passes through a strong magnetic field, the value remains constant regardless of changes in the vehicle's direction of travel.

Then, when the vehicle rotates once, the angle θ between the earth's magnetism and the output winding 1B changes from 0° to 360°, and accordingly, the output x, y of the above equation (point 15a, point 15b)
The vector locus whose components are the outputs x and y becomes a circle.

That is, by squaring each of the above expressions and adding them,
To summarize, {x−(K ₁・h・sinφ+K _2x )} ² + {y−(K ₁・h・cosφ+K _2y )} ² = (K ₁ H) ² , and the vector locus of x and y is 3
With radius K ₁ H as shown in the figure, K ₁ h in the x-axis direction.
sinφ+K _2x , a circle whose origin has been moved by K ₁・h・cosφ+K _2y in the y-axis direction.

In FIG. 1, reference numeral 2 denotes an arithmetic unit which executes the arithmetic processing of the flowchart shown in FIG. 4 using a known microcomputer system. First, the outputs x and y of the direction detection section 1 are read in step 101, and the origin movement amounts x _pffset and y _pffset (initial values are zero in step 100) are each subtracted in step 102, which serves as distortion amount correction means. Then, the values x' and y' of the outputs x and y excluding the amount of movement of the origin are determined. However, the amount of movement of the origin x _pffset . Since the initial value of y _pffset is zero, at first the values of x' and y' are not accurate values excluding the amount of movement of the origin, but by repeating the following calculation, they approach accurate values. That is, in steps 103 and 104 as a determination means, when either of these x' or y' is zero, the radius of the vector locus of the output x, y of the other y' or x' of the direction detection unit ₁ is determined From the constant R (reference value) corresponding to H, move the origin x _pffset
Alternatively, y _pffset is determined and stored in steps 107 to 112, which constitute the distortion amount calculation storage means (it is stored regardless of the operating state of the vehicle).

In other words, when the origin movement amount x _pffset = 0, y _pffset = 0, x and x' and y and y' match as shown in Figure 7a. For example, if there is a trajectory at point A , x=
Since x'=0 and y=y'≧0, step 10
In step 8, the calculation y-R is performed to obtain a new y _pffset . Therefore, the relationship between the x and x' axes is as shown in FIG. 7b. At this point, yottset does not yet exactly match the origin movement amount (K ₁ · h · cosφ + K _2y ) in FIG. 3.

Next, in FIG. 7b, if the trajectory reaches point B, for example, y'=0 and x'<0, so in step 112, the calculation x _pffset =x+R is performed,
Find a new x _pffset . Therefore, the relationship between the y and y' axes is as shown in FIG. 7c.

Then, in Figure 7c, again as in Figure a.
When it reaches point C where x'=0, y _pffset as shown above
(Since y'<0, y _pffset =y+R at step 109).

In this way, by repeating the calculation of the origin movement amount yottset or x _pffset at a predetermined time of fixed x or y such as x'=0, y=0, the origin movement amount (K ₁・h・sinφ＋K _2x ) and (K ₁・
h·cosφ+K _2y ) are obtained as the amount of distortion shown in FIG. 5, that is, the amount of movement of the origin x _pffset and y _pffset .

When x' and y' are not zero, in step 105, which serves as an azimuth calculation means, θ=
The calculation tan ^-1 (x'/y') is performed, and an azimuth signal θ corresponding to the traveling direction of the vehicle is output at step 106.

The direction detecting device including this calculation unit 2 is brought into operation by receiving power supply by turning on a power switch dedicated to this device (power may be supplied by turning on the vehicle ignition key switch), and the direction detecting device is activated by the amount of distortion. is configured to be stored (non-volatile storage) regardless of the on/off state of this power switch.

In this embodiment, a ring core type flux gate sensor is shown as the direction detection sensor 10, but other flux gate sensors, Hall elements, etc. may be used instead.

Furthermore, the azimuth signal θ may be made into a 2N-divided azimuth signal by level comparison instead of using the calculation tan ⁻¹ (x′/y′).

Furthermore, the calculating section 2 can be realized not by digital processing by a microcomputer system but by combining a comparison circuit, an addition/subtraction circuit, etc. in an analog manner.

Furthermore, this direction detection device can be used not only for vehicles but also for
It may also be applied to ships, airplanes, and other measuring instruments. Furthermore, in the above embodiment, when either x' or y' is zero, the other y' or x' is used for calculation.
The value of the other y' or x' when the value of x' or y' is a certain predetermined value other than zero may be used.

〔Effect of the invention〕

As described above, the present invention has the excellent effect that the direction correction is automatically performed by the occupant of the moving object simply by driving the moving object normally, eliminating the need for troublesome operations for correction. be.

Moreover, since the amount of distortion is corrected sequentially while the moving object is moving, even if the distortion of the earth's magnetic field due to the residual magnetism of the moving object or the distortion of the azimuth detection unit changes, the amount of distortion will automatically change to ensure accurate progress of the moving object. This has the excellent effect of easily generating an azimuth signal corresponding to the azimuth.

[Brief explanation of the drawing]

FIG. 1 is an electrical wiring diagram showing an embodiment of the present invention;
Figure 2 1, 2, 3, and 4 are voltage waveform diagrams used to explain the operation of the direction detection section, Figure 3 is an explanatory diagram used to explain the operation of the direction detection section, and Figure 4 is a calculation showing the calculation process of the calculation section. 5 is an explanatory diagram for explaining the arithmetic processing of the arithmetic section, FIG. 6 is a block diagram showing the configuration of the present invention, and FIG. 7 is an explanatory diagram for explaining the arithmetic process of the arithmetic section. DESCRIPTION OF SYMBOLS 1... Direction detection section, 2... Calculation section, 2A... Determination means, 2B... Distortion amount calculation storage means, 2C... Distortion amount correction means, 2D... Direction calculation means, 10... Direction detection sensor.

Claims (1)

[Scope of Claims] 1. An azimuth detection unit that is attached to a moving body and detects the azimuth of the earth's magnetic field using two orthogonal components, and a azimuth signal that calculates the azimuth using the two orthogonal electrical signals from the azimuth detection unit. In the azimuth detecting device, the azimuth detecting device determines whether one of the orthogonal two-component electrical signals from the azimuth detecting section is equal to a predetermined value at a predetermined period. a determination means for automatically determining the value of the other electrical signal and a predetermined reference value when one of the two orthogonal electrical signals is determined to be equal to the predetermined value; distortion amount calculation storage means for automatically calculating and storing the amount of distortion of the earth's magnetic field with respect to the other value; An orientation detection device comprising: a distortion amount correcting means that automatically corrects the distortion amount based on the distortion amount; and an orientation calculating means that calculates the orientation using the corrected orthogonal two-component electrical signals.