JPH10148502A - Position detecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide such a position detecting method that can suppress influences of noises, magnetic field of the earth, magnetic field of commercial- use a.c. current radiating from underground line, etc., and realize more accurate detection. SOLUTION: A horizontal magnetic field 21 and a vertical magnetic field coil 22 which generate a magnetic field in different direction as single or a plurality of exciting coils, are provided to a point to be measured, and these exciting coils are alternately excited by a driving circuit 23 so as to generate an a.c. current magnetic field having a different element alternately. A magnetic field detector (receiver 25) having signal or a plurality of receiving coils 24 as a detecting coil is moved at measuring point, thus detecting a.c. current magnetic field and directional element at desired points to the respective exciting timing, and they are converted into voltage signal. Then this signal is separated into two signals through a switch that is synchronized with the exciting timing of the exciting circuit, and the two signals is amplified by a differential amplifier so as to obtain a point of exciting coil according to such a pint where the output of the differential amplifier becomes zero.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a transmitter provided at a tip of a propulsion device for excavating a tunnel or a monitoring device for a pipe such as a nonmetallic pipe, and detects a magnetic field generated by the transmitter from the ground. The present invention relates to a position detection method that attempts to specify a position. Further, by applying this principle, the position of a moving vehicle is detected, and at the same time, a vehicle is mounted on the road side by using a coil of a transmitter and a detector. It is possible to detect the approach of a vehicle in a non-contact manner or to send an arbitrary signal to the vehicle from the road side.

[0002]

2. Description of the Related Art When an arbitrary device is placed in a tunnel or underground pipe, a method of measuring the position of the device from the ground is as follows.
There is a method using a gyroscope and the like, and commercialization is being performed. However, in this method, the gyro does not operate accurately for a gentle inclination or bend, and an error of an integrator for integrating the output of the gyro overlaps, and it is difficult to specify the position accurately. In order to solve this problem, an electromagnetic method and a method using sound were tried.

[0003]

However, in the method using sound, the propagation of sound is complicated and the attenuation is large, so that the position cannot be specified. In addition, the conventional electromagnetic method uses a magnetic field distribution of a single magnetic field.In this case, at the null point of the magnetic field strength, the magnetic field strength is extremely weak, and the position of the null point cannot be specified accurately, The method of obtaining the maximum value of the magnetic field is difficult to locate the peak,
Trouble that unexpected output appears when moving the search coil to detect the magnetic field strength under the influence of the earth's magnetic field, malfunction due to the influence of the AC magnetic field generated from the underground wire for commercial AC power supply, etc. There are many problems,
Practical application was difficult.

[0004] The present invention has been made in view of these points, and suppresses the influence of noise, the influence of the earth's magnetic field, the influence of a commercial AC magnetic field radiated from an underground wire, and the like, thereby achieving more accurate detection. An object of the present invention is to provide a position detection method capable of solving the above problems.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a plurality of exciting coils, excites each exciting coil in a time-division manner, and uses an amplifier synchronized with a drive signal of the exciting coil to control each exciting coil. The purpose is to detect the generated magnetic field and measure the position of the exciting coil from the ratio of each output. In this method, the ratio of the magnetic field strength is used not at the null point of the magnetic field but at the point where the mutual magnetic field strength is strong, so that the magnetic field strength at the measurement point is high, so that not only can the effect of noise be reduced, but also each signal is amplified by a differential amplifier. In this method, the influence of the earth's magnetic field and the influence of the commercial AC magnetic field radiated from the underground wire can be minimized. Hereinafter, the present invention will be described specifically.

According to a first aspect of the present invention, at a point to be measured, a single or a plurality of exciting coils for generating magnetic fields in different directions are provided alternately, and these exciting coils are alternately excited by an exciting circuit to be alternately provided. At the measurement point, an AC magnetic field having a different component is generated, and a magnetic field detector having a single or a plurality of detection coils is moved to detect an AC magnetic field and a directional component at an arbitrary point with respect to the respective excitation timings. Converted into a voltage signal, this signal is separated into two signals by a switch synchronized with the excitation timing of the excitation circuit,
The two signals are applied to a differential amplifier, and the position of the exciting coil is determined from the position where the output of the differential amplifier becomes zero.
The position detection method was used.

According to a second aspect of the present invention, a plurality of exciting coils are provided at an arbitrary distance from a point to be measured and alternately generate magnetic fields in different directions, and each exciting coil is provided at a different timing by an exciting circuit. Excitation to generate an AC magnetic field having a temporally different component.At the measurement point, the magnetic field detector having a single or a plurality of detection coils is moved to change the AC magnetic field and the directional component at any point with respect to the respective excitation timings. , And amplify this signal with a synchronous amplifier synchronized with the excitation timing of the excitation circuit, and determine the magnetic field strength at an arbitrary point by each excitation coil,
The position of the exciting coil was determined from the ratio of the respective magnetic field strengths.

According to a third aspect of the present invention, there is provided one or a plurality of excitation coils which are placed at an arbitrary distance from a point to be measured and which generate magnetic fields in a single direction or alternately in different directions. Excitation is performed at different timings by the excitation circuit to generate AC magnetic fields of different components in time.At the measurement point, the magnetic field due to the eddy current generated from the conductor near the excitation coil immediately after the excitation coil is cut off A magnetic field having an AC magnetic field and a directional component at an arbitrary point at a terminal voltage of the exciting coil or a detecting coil provided in the vicinity of the exciting coil, while selectively detecting the conductor and detecting the conductor by a synchronous amplifier synchronized with the coil. This signal is detected by a detector, this signal is amplified by a synchronous amplifier synchronized with the excitation circuit, and the magnetic field strength at an arbitrary point by each excitation coil is obtained. Determining the position of the exciting coil from the ratio of magnetic field strength, and a position detecting method.

Further, the invention of claim 4 provides the above-mentioned claim 1.
In the position detecting method of any one of the paragraphs 2, 2 and 3, a frequency different from the excitation frequency of the excitation coil is superimposed on the excitation coil, and an arbitrary signal is transmitted from the excitation coil to the detection coil while performing position detection and conductor detection. And the position detection method.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing an embodiment of the present invention, an example in which a circular loop coil, which is the easiest to describe, is used for an excitation coil and a detection coil will be described. First, as shown in FIG. 1, when a current I is passed through a circular coil having a radius a, a magnetic field generated at a point P at a distance r sufficiently far from the radius a of the coil is obtained.

[0011]

(Equation 1)

[0012]

(Equation 2)

[0013]

(Equation 3)

[0014]

(Equation 4)

[0015]

(Equation 5)

[0016]

(Equation 6)

[0017]

(Equation 7)

[0018]

(Equation 8)

[0019]

(Equation 9)

In order to detect the horizontal component and the vertical component of the magnetic field, respectively, like the transmission coil that generates the magnetic field, the receiving coil in which the plane formed by the coil loop for each magnetic field component is made horizontal or vertical. Can be detected by FIG. 4 shows the result in this case. The diagram of the coil indicated by an ellipse in FIG. 4 shows the relative directions of the transmitting coil and the receiving coil.

From FIG. 4, the horizontal component and the vertical component of the magnetic field generated by the transmitting coil are detected independently, and the point where the absolute values of the relative intensities of the respective magnetic fields match is determined. d can be determined. At this time, since the absolute value of the magnetic field strength shown in FIG. 4 appears symmetrically with respect to the horizontal distance x, the point where the absolute value of each magnetic field strength coincides occurs symmetrically with respect to the x-axis. Therefore, two points that satisfy this condition are determined, and the distance between the two points is determined. One half of this distance is the horizontal distance between the transmitting coil and the receiving coil.

FIG. 5 shows a specific apparatus for realizing the method of the present invention. In the figure, A denotes a receiver, and 1 denotes a receiving coil of the receiver A, which detects a magnetic field of a horizontal or vertical component depending on the arrangement of the coil. Reference numeral 2 denotes a resistor for adjusting the input impedance and the amount of negative feedback. 3
Is a first-stage amplifier, which amplifies the voltage received by the receiving coil 1. Reference numeral 4 denotes a synchronous switch, which is alternately switched in synchronization with another synchronous amplifier. 5 is a differential amplifier,
A signal corresponding to the magnetic field of the horizontal or vertical component is applied to each differential input to amplify this difference. Reference numeral 6 denotes an integrator, which averages and smoothes the output of the differential amplifier 5. Reference numeral 7 denotes a feedback compensation attenuator that adjusts a negative feedback amount for negatively feeding back a part of the output of the output terminal 10 of the receiver A. Reference numeral 8 denotes an inverting amplifier having a gain of -1, which is added to the first-stage amplifier 3 through a resistor 9 so that a part of the output signal becomes negative feedback in addition to the negative feedback switch of the synchronous switch 4. The negative feedback effect of the feedback compensation attenuator 7, the inverting amplifier 8, and the resistor 9 works effectively when the received signal is weak or has a lot of noise, but is not required when the received signal is strong.

B denotes a drive circuit, and 11 denotes a crystal oscillator, which sends a pulse signal generated by the crystal oscillator 11 to a timing generator 13 via a frequency divider 12, and outputs the pulse signal from the timing generator 13 to the receiver. A switching signal is sent to the synchronous switch 4 of A and a horizontal / vertical switch 14 of the transmitter C described later, and an excitation signal is sent to the horizontal / vertical switch 14. Further, a mask signal is sent to the first-stage amplifier 3 of the receiver A. C is a transmitter, and the excitation signal is input to the horizontal / vertical switch 14 of the transmitter C, and the vertical drive circuit 15 or the horizontal drive circuit 16 is operated by the switch signal. These vertical drive circuit 15 and horizontal drive circuit 16
, The vertical magnetic field coil 17 and the horizontal magnetic field coil 18 which are positioned vertically with respect to each other are excited.

FIG. 6 explains the operation of the circuit shown in FIG. 5. In the period T1, the horizontal magnetic field coil 18 is excited, the voltage of the receiving coil due to this magnetic field is received by the receiving coil 1, and this voltage is supplied to the first-stage amplifier. 3 and the signal is amplified by the synchronous switch 4 and applied to one terminal of the differential amplifier 5. At the end of T1,
The current of the horizontal magnetic field coil 18 is cut off. T2 is a period for masking. At time T3, the vertical magnetic field coil 17 is excited. At this time, the amplified reception voltage is also applied to the other terminal of the differential amplifier 5 by the synchronous switch 4. T3
At the end of the period, the current of the vertical magnetic field coil is also cut off. T4 is a transient voltage mask period. Similarly, T5, T6, T
7 and T8 are repeated, and the difference between the received voltage of the component of the horizontal magnetic field coil 18 and the received voltage of the component of the vertical magnetic field coil 17 received by the receiving coil is amplified.
Is operated so that the output of the output terminal 10 of the receiver A becomes zero.

The magnetic field due to Hvy or Hhy in FIG. 4 becomes zero immediately above the exciting coil, and the polarity is reversed. Therefore, in an actual circuit, the direction of excitation of the exciting coil is reversed and the polarity of the received signal is switched so as to be in the same direction, or a polarity switch is provided at the output of the synchronization switch 4 of the receiver C, and the horizontal magnetic field and the vertical Although it is possible to compare the absolute value of the reception voltage due to the magnetic field, it is omitted in the drawings.

FIG. 7 shows that a horizontal magnetic field coil 21 and a vertical magnetic field coil 22 are installed in a propulsion pipe 20 buried or excavated in the underground 19, and these coils 21 or 22 are alternately excited by a drive circuit 23. , Receiver 2 installed on the ground
5 shows a schematic diagram when the receiving coil 24 is attached and the depth y and the position of the sinus are measured. Here, the synchronization amplifier and the excitation circuit of the receiver 25 are synchronized by a wired or wireless excitation signal reception circuit and a PLL circuit.

In this state, the search is performed by creeping the receiving coil 24 on the ground, and the null point where the horizontal component of the horizontal magnetic field coil 21 is equal to the vertical component of the vertical magnetic field coil 22 is obtained by switching the excitation polarity of the horizontal coil. If the plane is symmetric with respect to the plane coinciding with the plane of the horizontal coil, the condition of the above equation (18) is satisfied, and the condition is obtained symmetrically with respect to this plane. If the minimum distance between these two points is halved and this distance is divided by 0.281, the distance from the receiving coil 24 on the ground surface to the magnetic field coil 21 or 22 in the sinus can be obtained.
This position can be determined.

In this embodiment, the horizontal magnetic field coil 21 and the vertical magnetic field coil
2 are orthogonal to each other to generate a magnetic field orthogonal to each other, and the receiving coil 24 having a plane parallel to the ground is used on the ground, but a receiving coil having a plane perpendicular to the ground may be used.
This combination is optional, as shown in FIG. Further, the same object can be achieved by using one excitation coil, making the receiving coils orthogonal, and adding their outputs to a differential amplifier.
Further, the shape of the exciting coil and the shape of the receiving coil are arbitrary, and the arrangement center portion is not common, but may be arranged at an arbitrary position, and the number of the exciting coil and the receiving coil is also arbitrary.
In these cases, the magnetic flux distribution is different from that of the above-described embodiment, and the formula for obtaining the position is different, but if the magnetic flux distribution is obtained for this arrangement, the same object can be achieved.

When a conductor such as a metal approaches the exciting coil, a minute magnetic field is generated by the eddy current flowing through the conductor even after the exciting current of the exciting coil is completely cut off. The current of the exciting coil is cut off earlier than the decay time of the eddy current, and a mask time T2 or T3 shown in FIG. 6 is taken until the current of the exciting coil is completely cut off. If the start-up timing is delayed and a period during which no excitation is performed on each excitation coil is provided, a voltage is generated in the excitation coil by an eddy current of a nearby conductor, and it is possible to detect that the conductor approaches the excitation coil. In this case, in order to extend the detection distance, only the voltage generated in the excitation coil is selectively received by the switch, and this voltage is applied to the differential amplifier and amplified.

The circuit shown in FIG. 5 has a strong suppressing effect on the common mode voltage applied to the input of the amplifier due to the differential effect of the differential amplifier. Therefore, even if an in-phase voltage having a frequency significantly different from that of the excitation signal is applied to the excitation coil, the effect of position measurement does not change. Therefore, a signal of a different frequency is superimposed on the exciting coil, the modulated signal is modulated, separated by a filter by a receiving coil, and further, a modulation signal is transmitted from the exciting coil to the receiving coil by a method of demodulating this signal. This can be demodulated on the receiving coil side, and position measurement and communication can be performed simultaneously.

[0031]

According to the first and second aspects of the present invention, it is possible to obtain an extremely high detection sensitivity and a high resistance to disturbances such as terrestrial magnetism and noise by a differential effect with respect to a plurality of component differences of a magnetic field. This magnetic field can be easily detected by a movable magnetic detector even with a single-turn loop or a single-wire excitation coil with the return line grounded. Therefore, it is possible to easily and accurately determine the position of the excitation coil in the invisible part such as underground from the ground, accurately propell the underground pipe toward the target, and trace the position of the unmanned propulsion machine from the ground. it can. Furthermore, the exciting coil is laid underground in the shape of a long rectangle or ellipse along the road, and this magnetic field is detected by a detector provided on a moving body such as an automobile, and the output is used to control the direction of the automobile. Can be controlled so as to travel along. As described above, the present invention can be used not only for specifying the position of the exciting coil in the invisible portion but also for the purpose of guiding and detecting the vehicle by using the configuration.

According to a third aspect of the present invention, in addition to the effects of the first and second aspects of the present invention, it is possible to detect that a conductor has approached the vicinity of an exciting coil, and to use this as a vehicle detector. Becomes possible.

According to a fourth aspect of the present invention, in addition to the effects of the first and second aspects of the present invention, a frequency different from the exciting frequency of the exciting coil is superimposed on the exciting coil so that the measuring point and the measuring point can be measured at the time of position measurement. Communication can be performed with the measurement point, and position detection can be performed more accurately. In addition, the excitation coil is buried in the road so as to have a safe inter-vehicle distance, and whether or not the excitation coil in front of each excitation coil detects the vehicle is superimposed with a frequency different from the excitation signal. When transmitted and transmitted in a non-contact manner to the vehicle, it also functions as a collision prevention device.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a first principle of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a second principle of the embodiment of the present invention.

FIG. 3 is an explanatory diagram of a third principle of the embodiment of the present invention.

FIG. 4 is a graph showing a magnetic field intensity with respect to a moving distance x from a central axis when a vertical direction component and a horizontal direction component of a magnetic field generated by a transmission coil according to an embodiment of the present invention are detected by a reception coil;

FIG. 5 is a schematic configuration diagram of an apparatus used in an embodiment of the present invention.

FIG. 6 is an output waveform chart for explaining each operation of the device according to the embodiment of the present invention.

FIG. 7 is a schematic explanatory diagram showing an example in which the position of the tip of a propulsion pipe buried or excavated in the ground according to the embodiment of the present invention is detected from the ground.

[Explanation of symbols]

Reference Signs List A Receiver B Drive circuit C Transmitter 1 Receiving coil 2 Resistor 3 First stage amplifier 4 Synchronous switch 5 Differential amplifier 6 Integrator 7 Feedback correction attenuator 8 Inverting amplifier (gain-1) 9 Resistor 10 Output terminal 11 Crystal oscillator 12 Frequency divider 13 Timing generator 14 Horizontal / vertical switch 15 Vertical axis drive circuit 16 Horizontal axis drive circuit 17 Vertical magnetic field coil 18 Horizontal magnetic field coil 19 Underground 20 Propulsion pipe 21 Vertical magnetic field coil 22 Horizontal magnetic field coil 23 Drive circuit 24 Receiving coil 25 Receiver

Claims (4)

[Claims] At least one excitation coil for generating magnetic fields in different directions is provided at a point to be measured, and these excitation coils are alternately excited by an excitation circuit to generate alternating magnetic fields of different components. At the measurement point, the magnetic field detector having a single or a plurality of detection coils is moved to detect an AC magnetic field and a directional component at an arbitrary point with respect to the respective excitation timings, and convert this to a voltage signal,
This signal is separated into two signals by a switch synchronized with the excitation timing of the excitation circuit, and the two signals are applied to a differential amplifier. From the position where the output of the differential amplifier becomes zero, the position of the excitation coil is determined. A position detection method characterized by determining the position. 2. A plurality of exciting coils which are placed at an arbitrary distance from a point to be measured and alternately generate magnetic fields in different directions are provided, and each exciting coil is excited at a different timing by an exciting circuit, and is different in time. A magnetic field detector having a single or a plurality of detection coils is moved at a measurement point to detect an AC magnetic field and a directional component at an arbitrary point with respect to each of the excitation timings. Amplification is performed by a synchronous amplifier synchronized with the excitation timing of the excitation circuit, a magnetic field intensity at an arbitrary point by each excitation coil is obtained, and a position of the excitation coil is obtained from a ratio of each magnetic field intensity. ,
Position detection method. 3. A single or plural excitation coils which are placed at an arbitrary distance from a point to be measured and generate single or alternate magnetic fields in different directions are provided, and the respective excitation coils are excited at different timings by an excitation circuit. Then, an AC magnetic field having a temporally different component is generated, and at a measurement point, a magnetic field due to an eddy current generated from a conductor near the excitation coil is synchronized with the excitation coil immediately after the excitation coil is cut off. While selectively detecting with an amplifier and detecting the conductor, an AC magnetic field and a directional component at an arbitrary point are detected with a terminal voltage of an exciting coil or a magnetic field detector having a detecting coil provided near the exciting coil. The signal is amplified by a synchronous amplifier synchronized with the excitation circuit, and the magnetic field strength at any point by each excitation coil is obtained. A position detecting method, wherein a position of an exciting coil is obtained. 4. The apparatus according to claim 1, wherein a frequency different from the excitation frequency of the excitation coil is superimposed on the excitation coil, and an arbitrary signal is transmitted from the excitation coil to the detection coil while performing position detection and conductor detection. 2. The position detecting method according to any one of the items 2 and 3.