JPH09325003A - Detection of position - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve noise-proofing property so as to detect the direction of an object to be measured according to desired observation point by obtaining the arrangement direction of receiving coil so that the phases of individual measurement signals measured by a plurality of receiving coils may match with each other. SOLUTION: First and second receiving coils 16 and 17 measure the magnetic field intensities of first and second transmitting coils 6 and 7, and send the measurement signals to first and second signal measuring devices 20 and 21. Both measurement signals and reference signal with the same frequency as that of carrier of a signal supply device 10 are detected through synchronization, and relative position between transmitting coils 6 and 7 and receiving coils 16 and 17 and the magnetic field intensity corresponding to the phase of signal wave are outputted to a signal indicator 24. Next, a displacement bar 14 is turned or shifted parallely so that the phases of signals that the coils 16 and 17 are detected through synchronization may match with each other, and the relative positional relation between the coils 16 and 17 and the coils 6 and 7 is obtained as a phase difference. Thus, the arrangement direction of the coils 16 and 17 shows the position of an underground embedded tube 1, so that the direction where the tube 1 is located can be detected according to observation point.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting method for measuring a magnetic field strength to detect a position between two points, and in particular,
The present invention relates to a position detection method for detecting the position of underground pipes buried underground such as water and sewer pipes, gas pipes, power cables, and telephone cables.

[0002]

2. Description of the Related Art Conventionally, as this kind of position detecting method,
A detector with an integrated transmitter and receiver is installed at the observation point, and an induced current is caused to flow in the underground buried pipe by the transmitted magnetic field generated by the transmitter, and the magnetic field generated by this induced current is received by the receiver. In Japanese Patent Laid-Open No. 4-198889, the position of the buried pipe is detected by synchronously detecting the output signal of the receiver with the reference signal from the oscillator and measuring the output change of the receiver. Is disclosed in.

[0003]

By the way, in the position detecting method as proposed above, there is a device at the observation point which uses a signal similar to the oscillation frequency from the oscillator, or when the signal jumps between the cables, the reference is made. When external noise that is in phase with the signal or the output signal of the receiver exists, external noise interferes with the reference signal and output signal, causing measurement errors, or the synchronization between the reference signal and output signal is disturbed, making measurement impossible. There was a point.

The present invention has been made in view of the above problems, and an object of the present invention is to improve noise resistance and to change the direction in which an object to be measured is located from an arbitrary observation point. An object of the present invention is to provide a position detecting method capable of detecting with high accuracy. The above and other objects and novel features of the present invention will be apparent from the description of the present specification and the accompanying drawings.

[0005]

[Means for Solving the Problems] To achieve the above object,
A position detecting method according to the present invention includes a plurality of receiving coils having a center of a magnetic detection surface arranged on the same straight line at an observation point, a first transmitting coil having the same central point in an object to be measured, and a first transmitting coil and a first transmitting coil. Two transmission coils are inserted, the carrier wave is spread-spectrum-modulated, then AM-modulated and given to the first and second transmission coils to generate a magnetic field in the first and second transmission coils. The magnetic field strength is measured by a plurality of receiving coils, and the individual measurement signals measured by the plurality of receiving coils are synchronously detected by the carrier waves to the first and second transmitting coils that are spread spectrum modulated, and the plurality of receiving coils measure the magnetic field strength. The position of the object to be measured is detected by comparing the phases of the individual measured signals and determining the arrangement direction of the plurality of receiving coils such that the phases match.

Therefore, in the present invention, the carrier wave is spread-spectrum-modulated and AM-modulated and then transmitted to the first and second transmission coils, and the first and second transmission coils generate a magnetic field. Next, the plurality of receiving coils measure the magnetic field strengths of the first and second transmitting coils, and the measurement signals of the magnetic field strengths of the first and second transmitting coils and the spread spectrum modulated carrier wave are synchronously detected. Then, the array direction of the receiving coils in which the phases of the individual measurement signals measured by the plurality of receiving coils match is obtained, and the position of the measured object is detected.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below in detail with reference to the drawings. In describing the embodiments, those having the same functions will be denoted by the same reference numerals. FIG. 1 is a schematic configuration diagram of a position detection system used when implementing a position detection method according to an embodiment of the present invention, and FIG. 2 is a signal processing for explaining the position detection method according to an embodiment of the present invention. FIG. 3 is a block diagram of a system, FIG. 3 is a signal waveform diagram supplied to a transmission coil according to the position detecting method of one embodiment of the present invention, and FIG. 4 is transmission / reception according to the position detecting method of one embodiment of the present invention. It is a waveform diagram of the relative position of a coil and the observation signal at that time.

In the position detecting system shown in FIG. 1, a movable carriage 2 which is movable in the longitudinal direction is introduced into an underground buried pipe 1 which is an object to be measured, and wheels 3 of the movable carriage 2 are provided with rotary encoders or the like. A wheel rotation amount sensor (not shown) is attached, and a control device 4 for measuring the traveling distance of the moving carriage 2 by a signal output from the wheel rotation amount sensor is connected via a signal line 5.

On the movable carriage 2, as magnetic generation means,
The first transmission coil 6 and the second transmission coil 7 are mounted so as to be orthogonal to each other with the same point on the same axis as the central axis X of the underground buried pipe 1 as the center. First transmission coil 6
Is connected via a signal line 8 to a signal supply device 10 that supplies an alternating current, such as an oscillator, arranged outside the underground buried pipe 1. The second transmission coil 7 is connected to the signal supply device 10 via a signal line 9.

A magnetic detection device 11 is movably arranged at an observation point on the ground. In the magnetic detection device 11, a pair of support plates 13 and 13 are installed upright on a base 12,
Between the pair of support plates 13, 13, the displacement rod 14 is rotated by the moving means 15 about an axis parallel to the central axis X of the underground buried pipe 1 and is perpendicular to the peripheral surface of the displacement rod 14. It is supported so as to move parallel to the direction.

At both ends of the displacement bar 14, a first receiving coil 16 and a second receiving coil 17 are provided as magnetic detection coils.
Are wound around the magnetic detection surface 16 of the first receiving coil 16 and the second receiving coil 17, respectively.
a and the magnetic detection surface 17a of the second receiving coil 17 are arranged in parallel so that their center positions are on the same straight line.

First and second signal measuring devices 20 and 21 are connected to the first and second receiving coils 16 and 17 through signal lines 18 and 19, respectively, and the first and second signal measuring device 2 are connected.
A signal display 24 having a display screen 24a such as an oscilloscope for displaying a signal wave is connected to 0 and 21 via signal lines 22 and 23. In addition, the first and second
The signal measuring device 20, 21 and the signal supply device 10 are connected to the signal line 2
Connected by 5.

The signal supply device 10 includes a signal generator 10a for generating a sine wave signal, a spread code generator 10b for generating a signal of a predetermined code sequence, and a sine wave signal modulated with a signal of the code sequence. It has a spread spectrum modulator 10c that spreads in a wide band and an AM modulator 10d that AM-modulates the signal output from the spread spectrum modulator 10c.
On the display screen 24a, the vertical axis represents the reception level (magnetic field strength) and the horizontal axis represents time (t) (see FIG. 2).

Since the position detecting system is constructed as described above, the position detecting method using the position detecting system is as follows.
First, the moving carriage 2 is a plane in which the centers of the first and second transmitting coils 6 and 7 include the central axis X of the underground buried pipe 1 and the centers of the magnetic detecting surfaces 16a and 17a of the first and second receiving coils 16 and 17, respectively. Move it so that it is located at the intersection with. Then, from the signal supply device 10, the COS is applied to the first transmission coil 6.
The second transmission coil 7 is provided while applying the modulated alternating current.
Is supplied with a SIN-modulated AC current, and the second transmission coil 7 generates a magnetic field in a direction in which the central magnetic field line Mc is orthogonal to the central axis X of the underground buried pipe 1 in any phase.

At this time, the carrier wave is several K to several hundred KHz,
For example, using 200 KHz, the modulating wave is several hundred Hz,
For example, 400 Hz is used. As a result, the COS modulated wave and the SIN modulated wave are transmitted from the first and second transmitting coils 6 and 7 so that the rotating magnetic field is the same as when one coil is rotating. In this case, the spread spectrum modulator 10c converts the sine wave signal A (see FIG. 3A) from the signal generator 10a into the spread code generator 10b.
3 is spread-spectrum-modulated with the signal B of the code sequence from (see FIG. 3B). Then, the spread spectrum modulated signal C (see FIG. 3 (c)) is SI-converted by the AM modulator 10d.
The N modulation signal D (see FIG. 3D) and the COS modulation signal E (see FIG. 3E) become the SIN modulation signal D, which is transmitted to the second transmission coil 7, and the COS modulation signal E is the first.
It is transmitted to the transmission coil 6. The spread spectrum modulated signal C is also transmitted to the first and second signal measuring instruments 20 and 21 as a reference signal.

The first receiving coil 16 and the second receiving coil 17 measure the magnetic field strengths of the first and second transmitting coils 6 and 7, and the measured signals are measured by the first and second signal measuring devices 2.
It is transmitted to 0 and 21. First and second signal measuring device 20,
Reference numeral 21 synchronously detects the measurement signals from the first and second receiving coils 16 and 17 and a reference signal having the same frequency as the carrier wave obtained from the signal supply device 10 at 200 KHz (spread spectrum modulation). The signal C is demodulated by the code sequence signal B.), the first and second transmission coils 6 and 7.
Then, the reception level (magnetic field strength) corresponding to the relative positions of the first and second reception coils 16 and 17 and the phase of the signal wave is output to the signal display 24.

As a result, the display screen 2 of the signal display 24 is displayed.
At 4a, the measurement signals 16b and 17b of the first and second receiving coils 16 and 17 are obtained as a sine wave of 400 Hz. Next, a plurality of first and second receiving coils 16 and 17
The displacement rod 14 is rotated or moved in parallel so that the phase of the signal after the synchronous detection, which is detected more, matches. At this time,
The measurement signals 16b and 17b obtained from the first receiving coil 16 and the second receiving coil 17 are phase difference in the relative positional relationship between the first and second receiving coils 16 and 17 and the first and second transmitting coils 6 and 7. When the two match, the direction of the alignment straight line of the first receiving coil 16 and the second receiving coil 17 indicates the center of the first and second transmitting coils 6 and 7 (FIG. 4A). reference). If they do not match, the first
The attitude control directions of the receiving coil 16 and the second receiving coil 17 are determined.

For example, when the phase of the first receiving coil 16 is advanced, it is corrected by moving the first receiving coil 16 upward or the second receiving coil 17 downward (FIG. 4 (b)). First receiving coil 16
If the phase is delayed, the second receiving coil 17 is moved upward or the first receiving coil 16 is moved downward (see FIG. 4C).

The phase directions of the first and second transmitting coils 6 and 7 and the first and second receiving coils 16 and 17 are determined by the winding direction and the like. In this way, the arrangement direction of the first receiving coil 16 and the second receiving coil 17 indicates the position of the underground buried pipe 1, and the direction in which the underground buried pipe 1 is located is detected from the observation point.

As described above, according to the position detecting method of the present embodiment, the first and second receiving coils 16 and 17 in which the phases of the measurement signals 16b and 17b of the first and second receiving coils 16 and 17 coincide with each other. The orientation of the array of indicates the center position of the first and second transmission coils 6 and 7. In this case, since the communication between the first and second receiving coils 16 and 17 and the first and second transmitting coils 6 and 7 is performed by the spread spectrum modulated carrier wave, the noise resistance is improved and the measurement error is improved. Is reduced.

Although the position detecting method according to the embodiment of the present invention has been described above in detail, the present invention is not limited to the position detecting method according to the above embodiment, and is described in the claims of the present invention. Various modifications can be made in the design without departing from the spirit of the invention. For example, a spread spectrum modulation of a sine wave can be converted into a direct spread (D
D) method, frequency hopping (FH) method, time hopping (TH) method, hybrid method or the like may be used.

[0022]

As can be understood from the above description, in the position detecting method of the present invention, the spread spectrum communication of the carrier wave is performed between the transmitting coil and the receiving coil, so that the noise resistance is improved and the measurement is performed. The error is reduced. As a result, the direction in which the measured object is located can be detected with high accuracy from an arbitrary observation point.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a position detection system used when implementing a position detection method according to an embodiment of the present invention.

FIG. 2 is a block diagram of a signal processing system for explaining a position detecting method according to an embodiment of the present invention.

3 (a) to 3 (e) are signal waveform diagrams supplied to the transmission coil according to the position detecting method of the embodiment of the present invention.

4A to 4C are waveform diagrams of relative positions of transmitting and receiving coils according to the position detecting method of one embodiment of the present invention and observed signals at that time.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Underground piping 2 Mobile truck 3 Wheels 4 Control device 5,18,19,22,23,25 Signal line 6 1st transmission coil 7 2nd transmission coil 8 and 9 Power line 10 Signal supply device 10a Signal generator 10b Spreading code Generator 10c Spread spectrum modulator 10d AM modulator 11 Magnetic detection device 12 Base 13 Support plate 14 Displacement rod 15 Moving means 16 First receiving coil 17 Second receiving coil 20 First signal measuring instrument 21 Second signal measuring instrument 24 Signal display 24a display screen

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G01V 3/10 G01V 3/10 BF

Claims (1)

[Claims] 1. A plurality of receiving coils having a center of a magnetic detection surface arranged on the same straight line at an observation point, and a first transmitting coil and a second transmitting coil having the same central point and orthogonal to each other in an object to be measured. After being inserted, the carrier wave is spread-spectrum-modulated, then AM-modulated and given to the first and second transmission coils to generate a magnetic field in the first and second transmission coils,
The magnetic field strengths of the first and second transmitting coils are measured by the plurality of receiving coils, and individual measurement signals measured by the plurality of receiving coils are spread-spectrum-modulated to the first and second transmitting coils. By synchronously detecting with, the phases of the individual measurement signals measured by the plurality of receiving coils are compared, and the arrangement direction of the plurality of receiving coils such that the phases match each other is obtained. A position detecting method characterized by detecting the position.