JPS599510A - Azimuth detecting device - Google Patents

Abstract

PURPOSE:To make it possible to detect azimuth accurately, by decreasing and increasing the amplification factor of an AC signal amplifier, in correspondence with the magnitude of a magnetic field component, which is not related to the azimuth of a vehicle. CONSTITUTION:A sensor 2 is of a fluxgate type. An exciting coil 14 is applied to a part of an annular core 13. Both ends of the coil 14 are connected to an oscillator 15. The coil is excited by an AC signal. An output coil 10 is provided in the direction of one diameter of the core 13. A coil 11 is provided in the direction perpendicular to said diameter. The coil 10 is arranged in the x axis and the advancing direction of a vehicle. The sensor 2 is saturated by an exciting frequency. Distorted waveforms are generated in the coils 10 and 11. The amplitude of the second harmonic waves of said waveforms is proportional to a DC magnetic field which is applied to the sensor 2. When the magnetizing component becomes large, a resistor 36 is connected in parallel with a resistor 34, and the amplification factor of an operation amplifier 40 is decreased. The output signal of the amplifier 40 is inputted to a sample and hold circuit 60. The amagnetic field component, which is obtained by changing the sample and held peak value into a DC level, is converted into digital value. The value is inputted to a computer system 63. When the magnetizing amount is larger than the specified amount, a signal, which turns ON switches 50 and 51, is sent out, and the amplification factor is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a direction detection device used to detect the direction of movement of a vehicle, etc., and more specifically, the present invention relates to a direction detection device used to detect the direction of movement of a vehicle, etc. The present invention relates to an azimuth detecting device that enables accurate and highly sensitive azimuth measurement by performing gain control to prevent this.

A conventional direction detection method will be described.

As shown in Figure 1, the positive direction of the x-axis is the direction of travel of the vehicle, and the rectangular coordinate system o-x is fixed to the vehicle 1 on a horizontal plane.
Take y. The magnetic sensor 2 has a magnetic sensor probe 2x that detects a magnetic field component in the x-axis direction and a magnetic sensor probe 2v that detects a magnetic field component in the y-axis direction, and the pixel elements are mounted on the vehicle so as to be perpendicular to each other. Fixed. Now, let the horizontal component of the earth's magnetic field be the horizontal component, and its X and y components are 1-IX and I, respectively.
Let it be l/.

As shown in the figure, the direction of the horizontal component H of the earth's magnetism is inclined in the y-axis direction by θ0 with respect to the positive direction of the x-axis. In other words, the direction of travel of the car is from north (N) to θ0 east (E
). This horizontal component of geomagnetic force H is
A circuit system for detecting an X-direction component and a circuit system for detecting a y-direction component, which have exactly the same characteristics, are used to detect x and y components, respectively.
The magnetic field components 1-IX, l-IV are measured. H
X and 1-1y are expressed by the following equation using θ.

HX=lFTICO8θ...(1) HV=lFTlsinθ・(2) Therefore, the direction of travel of the car (number 0 representing O, θ-tan
1 (liy/Ilx), which tells you how many degrees the car's direction of travel is tilted eastward from 1.

Then, as the advance i-j 7j l/ll of the center rotates once in the order of north, east, south, and west, it is measured, and the horizontal component H of the earth's magnetism is measured by the locus It, O-xy. If we consider the zodiac system as fixed, as shown in Fig. 2, the radius r centered at the origin is
-1 5 on the circumference of FT1 is 11. 'n Rotate in the M1 rotation direction.

However, in reality, J occurs not only due to the geomagnetic field but also due to other causes! i field, and the total magnetic field vector Hs t detected by the -3 one-way detection means
, t, 1ris = p + FTc. Tatashi, HC is the horizontal component of the magnetic field caused by causes other than geomagnetism. Further investigation into the cause of FTC reveals that there is a magnetic field generated due to the magnetization of the vehicle. If the horizontal component of the magnetic field is Hr and the other force is FTa, then FTC
=ir +i:ja. Let us now examine the properties of 14r. Vehicles are generally made of ferromagnetic, magnetically hard materials such as iron. Therefore, it is easily magnetized by an external magnetic field, producing residual magnetism. Typically, it is likely to become magnetized when passing under a DC power line. In addition, it is easily magnetized by the surface current of the vehicle. The magnetic field that appears near the direction detection sensor due to the magnetization of the vehicle is uniquely represented by a coordinate system o-xy fixed to the vehicle. Therefore, the amount does not depend on the rotation of the vehicle. In other words, from the perspective of the direction detection sensor fixed to the vehicle, the horizontal component of the earth's magnetic field is
The horizontal component of the magnetic field due to magnetization is a DC component that does not depend on the rotation of the vehicle. , p during one revolution of the vehicle
When r is constant, the solid locus of the observed magnetic field vector that combines the two is as shown in Figure 2, with the center of the circle being [fr-('with a certain radius r = N'TI Draw a circle 7. In other words, 1), the vector locus when there is no disturbance of -1 is 11r.
The result is a parallel translation of -J. Furthermore, in reality, it is affected by the spatial magnetic field Ha other than the earth's magnetism outside the vehicle, and the influence is complex. However, when the vehicle is running, in terms of time, it is In general, F
While Ta is a short-term disturbance, HrG, once magnetized, remains until it is demagnetized, so it is a long-term disturbance.

Therefore, the problem is to compensate for Hr and find the horizontal component of the earth's magnetic field H and tj from jl and Ml' to detect the orientation.

By the way, while the magnitude of the horizontal component H of the earth's magnetism is conceptually constant over time, it is
Generally speaking, r varies greatly over a long period of time. Therefore, the dynamic range of the signal amplifier needs to be wide.

-5- On the other hand, in order to increase the measurement sensitivity, it is necessary to increase the amplification degree of the amplifier in the measurement circuit system. However, when the degree of amplification is increased, the amount of vehicle magnetization becomes larger (which causes the detected input signal level to increase and the amplifier to become saturated. To prevent this, conventional direction detection means The amplification factor was limited to a small value at the expense of sensitivity.

The present invention was made for the purpose of improving the above-mentioned drawbacks, and calculates the amount of magnetization from the detection signal, and when this value becomes larger than a predetermined value, prevents saturation of the amplifier circuit. Therefore, the amplification degree is switched to a small value, and when the amount of magnetization is smaller than a predetermined value, the amplification degree is increased to a large degree, thereby increasing the sensitivity and preventing saturation. The purpose is to

That is, the present invention includes a magnetic sensor for detecting the horizontal component of a magnetic field vector, an amplifying circuit means for amplifying the signal detected by the magnetic sensor, and an output signal of the amplifying circuit means. In the azimuth detecting device comprising a processing device for determining the azimuth by calculating the horizontal component of the geomagnetic field from the terrestrial magnetic field, and a display device for displaying the result, the processing 1! ! The device detects the horizontal component of the magnetic field vector detected by the magnetic sensor 9-
It has a function that selects the horizontal component unrelated to the direction in which the object faces, and sends a control signal to that effect when the magnitude of the horizontal component (unrelated to the direction) reaches a predetermined value or more. , the amplification circuit means is connected to receive the control signal from the processing device, and upon receiving the control signal, the amplification circuit means has an amplification degree capable of switching the signal amplification degree of the amplification circuit means to a low amplification degree. It consists of an azimuth detection device characterized by having a switching means.

Here, the magnetic sensor may be a flux gate magnetometer, or a sensor using a Hall element or a magnetoresistive element. In the magnetic sensor, two elements are usually arranged in mutually orthogonal directions on a horizontal plane. Then, the magnetic field vector component in that direction is detected by each sensor. However, it is not always necessary to arrange the two magnetic sensor probes perpendicularly to each other; instead, they can be arranged in two vector directions that are independent of each other, and the magnitude or direction of the magnetic field vector can be determined by performing correction processing later. It is also possible. or,
Here, one stage of amplifier circuit includes all generally known AC signal amplification circuit means. A processing device is a circuit section that inputs the above-mentioned output signal and converts it into a signal necessary for the processing device, a circuit section that stores the signal, etc., an arithmetic section that performs calculations, and a timing control between the circuits. It shall include a control unit, etc. In addition, the horizontal component unrelated to the direction in which the magnetic sensor faces refers to the horizontal component of the magnetization vector that magnetizes the vehicle at one end, but is not necessarily limited to this, and is not limited to the above-mentioned measurement. This refers to the component of a signal's solid trajectory that does not change when the vehicle makes one revolution.

In the above, it is described as Frr vectors 1 to 1. Further, as a method for selecting the horizontal force components that are unrelated to the orientation, any method of finding the center of a circle, since the vector locus of the measurement signal is a circle, can be used. For example, when detecting the X-direction component, store the maximum and minimum values of the back τ° of the output signal, and calculate the sum i1 [average value] and the average value processed in the same way for the ■-direction component. It is possible to find the center of the Muku1 locus using . Further, the DC component can be determined as the arithmetic average of all the measured signals. Furthermore, it is possible to obtain the equation of a circle using the least squares approximation method using the measured data, find the radius of the circle of the trajectory, and find the center of the circle of the vector trajectory. In addition, a general mathematical method for finding the center of a circle can be used. Further, here, it is assumed that the food ram does not change significantly while the vehicle rotates once, that is, while the vector trajectory is drawn once. Furthermore, the amplification degree of the amplifier circuit means 1) the ratio of the output voltage to the input voltage when the amplifier circuit means is considered as a black box.

Therefore, a method of changing the amplification factor of the amplifier circuit element itself or a method of lowering the input signal level can be used as means for switching the amplification degree.

Furthermore, a relay, an analog switch, or the like can be used as the switching means itself.

-9- Hereinafter, the present invention will be described in detail based on a specific example in which a digital computer using a microprocessor is used as the main part of the processing device according to the present invention.

FIG. 3 is a block diagram showing the overall configuration of the direction detection device. The output signal of the magnetic sensor 2 is inputted to the amplification circuit means 4, inputted to the amplification and post-processing device 6, and outputted to the display device 8 after signal processing.

First, the configuration of magnetic sensor +J2 will be explained.

FIG. 4 shows a slack gate type magnetic capacitor 2 used in this example.

An excitation coil 14 is provided on a part of an annular core 13 made of a magnetically hard material, and both ends of the excitation coil 14 are
It is connected to an oscillator 15 and excited by an alternating current signal of frequency F. On the other hand, an output coil 10 wound in the diametrical direction of one of the annular cores 13 and an output coil 11 wound in a direction perpendicular thereto are arranged. Output coil 10 (
The axes of the coils are oriented in the x-axis direction, and the coils are arranged in 10 stages in the direction of travel of the vehicle. Also, the axis number of Deno J-11 Ile 11, y
It is axially oriented and perpendicular to the direction of vehicle travel. and,
The output coil 10 detects the X-direction component of the magnetic field vector 1, and the output coil 11 detects the y-direction component of the magnetic field vector.

Here, the magnetic force side of the 7-lux gate type is configured to be easily saturated by the excitation frequency F, as is well known, and the output coil 1, which is the secondary winding, is configured to be easily saturated by the excitation frequency F.
A distorted waveform is generated at 0 and 11. The amplitude of the second harmonic of the strain waveform is proportional to the magnitude of the DC magnetic field applied to the magnetic force sensor 4''-2 of the fluff sedge type.

Next, the amplifier circuit means will be described.

A resistor 20 and a resistor 30 are connected to both ends of the output coil 10 in parallel thereto. The output coil 10 and the condenser 20 constitute a tuning circuit, which is configured to tune to the second harmonic of the excitation frequency. The tuned output signal is input to an operational amplifier 40. The operational amplifier 40 has a large degree of amplification determined by the resistors -11-32 and 34 when the magnetization component is small. On the other hand, if the magnetization component is large (when it becomes large), the resistance 3
6 is connected in parallel to the resistor 34 to reduce the amplification degree. The switch 50 is an asilog switch,
Alternatively, it is an amplification degree switching means composed of a relay or the like.

Next, the processing device 6 will be described.

The output signal number of the operational amplifier 40 is inputted to a sample hold circuit 60, where the peak value of the output signal is sampled and held. The peak value is sampled and held and the magnetic field component expressed as a DC level is sent to the AD converter 62.
The signal is input to the computer system 63, converted into a digital signal, and input to the computer system 63. Similarly, the y-component signal detected by the coil 11 is configured in exactly the same way as the circuit system when detecting the aforementioned X-component. The computer system processing will be described in detail later, but if the computer system calculates that the amount of magnetization is larger than a predetermined amount, a signal is sent to turn on the switches 50 and 51 to reduce the amplification. On the other hand, the corn 12-coater system 63 GJ drives the display device 8,
Displays the direction of travel of the vehicle. One rotation correction switch 6
4 is a switch that provides an operation start signal for determining the magnetization component by rotating the vehicle once.

The operation signal of the one-turn correction switch 64 is stored in a flip-flop 65, and the information is input to a computer system 63 for predetermined processing.

Next, the process of processing the combination 1-tasis-de 7=%G will be explained based on the flowchart i- in FIG. In step 110, initial settings of all parameters are made. Proceeding to the next step 120, it is determined whether the one-rotation correction switch 64 is on. When it is on, it means that the vehicle is rotated once and the magnetization component is determined. In step 130, signals in each direction are inputted. That is, the X component of the measurement value where the y component of the magnetic field vector of the measurement signal becomes zero is read as Xe and XW. Similarly, the y components of the measured values where the X component is zero are read as Yn and YS. FIG. 6 is an explanatory diagram showing these values. Then, in step 140, the average value of these values is calculated using the following equation.

Xer-(Xe 1Xw) / 2-=・-= (1
)Yer= (Yn +Ys)/2・・・・−・=
(2) In this way, the center of the circle of the vector locus (Xer).

Ver) has been found. In step 150,
Calculate the magnitude of the center vector. The value of Hr represents the amount of magnetization, which is a DC component that is unrelated to the orientation of the magnetic sensor. Then, in step 160I, the value Hr is set to a predetermined value (fi
Determination 1-1 whether or not the value is larger than Ch. Here, the value of ch is set to a different value depending on whether the current amplifier circuit has a high amplification degree or a low amplification degree. If it is larger than the predetermined value, the process moves to step 170 and a high-level magnetization signal is output. This means that the @magnetic vector is thicker than a predetermined value. Also, if it is smaller than a predetermined value, the process moves to step 180 and outputs a low-level magnetization signal. This means that the magnetization vector is thicker than a predetermined value. This means that the signal is smaller than a predetermined value. Then, in step 190, the signal is output and the flip 70 knob 65 for the m-14 rotation command is relit. By making the feedback resistors 36 and 37 connected to the input and output of the stew amplifiers 40 and 41 conductive and non-conductive accordingly, the amplification degree of these stew amplifiers is changed.

Also, if the 1 rotation switch is not pressed in step 120, @magnetic vector 1 hel, that is, the center of the vector locus has already been found, so J is entered in step 200.
3 and perform the direction MW. Then, the process moves to step 210, and the direction determined in step 200 is displayed as a north direction with a light display shade 1 not shown in FIG.

In the above examples]! I! Although the device was realized by a combicoater system that mainly handles digital signals, it is not necessarily limited thereto.Since the present invention is based on the above idea, it can also be used with other analog circuits and analog and digital signals. It can also be realized by a mixed circuit or the like.

In summary, the present invention detects a magnetic field component unrelated to the direction of the vehicle among the signals detected by the magnetic detection range, and when the magnetic field component is large, the amplification factor of the AC signal amplifier is lowered. This prevents the circuit from becoming saturated by holding it down. When the magnetic field component unrelated to the orientation is small, it is amplified with a large amplification factor, and the sensitivity is kept large. Therefore, according to the device of the present invention, the sensitivity of direction detection is not reduced, and even if the magnetization becomes large, the circuit will not be saturated.

Therefore, accurate direction detection is possible.

[Brief explanation of drawings]

FIGS. 1 and 2 are explanatory diagrams illustrating a method for detecting the horizontal component of a magnetic field vector. FIG. 3 is an overall configuration diagram of an orientation detection device according to an embodiment of the present invention. FIG. 4 is a configuration diagram of the magnetic sensor used in the same example. FIG. 5 is a flowchart 1 showing the processing of the computer system used in the same embodiment. FIG. 6 is an explanatory diagram showing a method for finding the center of a vector locus,
FIG. 7 is a plan view of a display device that displays orientation. = 16 = 1...Vehicle 2...Magnetic range 4...
- Amplifying circuit means 6... Processing device 8... Display device 10.11... Output coil 50.51...
・Analog switch 63...Computer system patent applicant Nippondenso Co., Ltd. Agent Patent attorney Hiroshi Okawa Original document Patent attorney Akio Maruyama -17- Figure 1 Figure 4 Figure 6 Figure 7 Figure 55-

Claims (1)

[Claims]! & Magnetic field vector horizontal component force is detected by an amplifying circuit means for amplifying the signal detected by the magnetic sensor, an output signal of the amplifying circuit means is inputted, and the horizontal component force of the earth's magnetic field is calculated from the signal. In a direction detection device comprising a processing device that obtains a direction by calculating the direction, and a display device that displays the result, the processing device is configured to calculate the direction of the direction by calculating the horizontal component of the magnetic field vector detected by the magnetic sensor. It has a function that selects horizontal force components that are unrelated to the direction in which the magnetic sensor faces, and when the magnitude of the horizontal force components that are unrelated to the direction reaches a predetermined value or more, it sends a control signal to that effect. and the amplification circuit means is connected to receive the control signal from the processing device, and when receiving the control signal, switches the signal amplification -1 of the amplification circuit means to a low amplification degree. An azimuth detection device characterized by having an amplification degree switching means.