JPH03260283A - Position detector of underground excavator - Google Patents

Abstract

PURPOSE:To make it possible to detect a deflection quantity with high degree of accuracy by moving forward either magnetic field generators or magnetic field detectors to bring them near each other, and performing the operation of a relative position of them based on the forward distance and magnetic field detection signals. CONSTITUTION:Magnetic field generators 14a - 14c consisting of a plurality of loops are provided on one of either the tip of underground excavators 10 and 20 or the forward standard position. In addition, a power supply device 19 exciting each of the loops with different frequency is provided. Magnetic field detectors 26a - 26c and filter devices 42a - 42c to pass detection signals of frequency corresponding to frequency exciting each of the loops are provided on the other. Either the magnetic field generators 14a - 14c or the magnetic field detectors 26a - 26c are advanced to bring them near each other. After that, the operation of a relative position of them is performed by a position operator 30 based on the forward distance and magnetic field detection signals, and a deflection quantity of the underground excavators 10 and 20 is detected.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a position detection device for detecting the position of an underground excavator excavating underground, and particularly relates to a position detection device for detecting the position of an underground excavator that is excavating underground.
The present invention relates to an underground excavator position detection device suitable for connecting two underground excavators underground.

[Conventional technology]

When constructing a tunnel under the sea, it is not possible to install many vertical shafts for launching underground excavators.

However, excavating long distances with a single underground excavator not only makes it difficult to discharge the excavated soil, but also involves many dangers. In order to shorten the excavation distance of an excavator, two underground excavators are started facing each other, and the tunnels excavated by each excavator are joined underground.

However, at the junction, the centers of both underground excavators are on the left and right,
If there is a vertical shift, the connected tunnel will become discontinuous, so it is necessary to find the relative positions of both underground excavators and correct the positional shift. Conventionally, when correcting the positional deviation between two underground excavators, the tunnel meter of each underground excavator was
The relative positional deviation between the two underground excavation fronts was determined by detecting the positional deviation from the reference position such as the starting point, and the relative positional deviation between the two underground excavation fronts, and corrections were made based on this positional deviation.

Conventionally, the following methods have been used to locate underground excavators underground.

■ Determine the position of the underground excavator from the reference point and the deviation from the planned line by underground surveying using transit, etc.

■ An optical transmitter that generates coherent light such as a laser beam is installed in the starting shaft of the underground excavator, and this device illuminates the tunnel planning line and illuminates the light spot on the target attached to the underground excavator. Read and determine the position, deviation, and declination of the underground excavator from the starting shaft.

■ Combine the azimuth gyro, pressure type subsidence gauge, inclinometer, and odometer based on the segment length assembled in the tunnel to find the relative position from the reference position.

However, each of the conventional methods for determining the position of the underground excavator described above has the following drawbacks, and it is difficult to accurately perform underground joints.

Method (2) is impractical because it requires many measurement points when excavating a tunnel in a curved manner, and it is not possible to measure in real time. In addition, with method (2), if the tunnel planning line is bent, the laser beam from the starting shaft cannot irradiate the target, and the optical transmitter must be moved to an appropriate position. Since light cannot be directly irradiated over the entire length of the planned line, each time the optical transmitter is moved, the mutual positional relationship between the target, the optical surveying device, and the tunnel planned line is actually measured, and the planned route is calculated based on the measurement results. After determining the position, deviation, and declination of the underground excavator, it is necessary to calculate the position, deviation, and declination of the underground excavator, which requires human effort to relocate the optical transmitter, measure, and calculate, reducing the efficiency of excavation work. There's a problem.

Furthermore, method (■) causes cumulative errors and is not suitable for long-distance excavation, and is also not suitable for excavating curves with a small radius of curvature or excavating tunnels with continuous curves. It is also unsuitable.

In addition, when measuring the relative positions of two underground excavators, as in the case of underground joints, the error further increases.

Therefore, the applicant installed a magnetic field generator on one of the two underground excavators to be connected underground, and installed a magnetic field detector on the other underground excavator to detect the magnetic field generated by the magnetic field generator. , a magnetic field detector is brought close to the magnetic field generator by a polling device, and a detection signal of the magnetic field detector and the excavation amount of the polling device are inputted to a calculation device to obtain a position detection device that can determine the relative position of the two. (Patent Application No. 1-223035).

[Intelligence B to be Solved by the Invention] However, since the position detection device shown in the above-mentioned Japanese Patent Application No. 1-223035 uses a rectangular loop cable as a magnetic field generator, there is a detection error. growing. In other words, the position detection device of Japanese Patent Application No. 1-223035 utilizes the technology of detecting the magnetic field generated by an infinitely long parallel cable or an approximately infinitely long parallel cable, so it does not require any other magnetic field to detect the magnetic field strength. The magnetic field generated from the pair of sides is also detected by the magnetic field detector, creating an error.

In other words, if the magnetic field generator can be considered as a parallel cable of infinite length, for example, if it is a rectangular loop with a ratio b/a of the long side to the short side a of 100, then the center between the long sides Comparing the offset position X' in the direction perpendicular to the long side from the measured value X with the offset position X' determined based on the strength of the magnetic field detected by the magnetic field detector, the slope is 1 as shown in Figure 9. Therefore, the offset position χ' obtained from the detected magnetic field has a value equal to the actually measured value X.

However, when b/a is made small, the strength of the magnetic field detected by the magnetic field detector is affected by the magnetic field generated by the short side a, and the horizontal axis is the measured value X, and the vertical axis is based on the detected magnetic field strength. The slope when taking the offset position X' determined by
This results in a detection error.

Therefore, it is conceivable to configure the magnetic field generator with a plurality of rectangular loops having a large ratio of long sides to short sides. but,
In this case, if a plurality of loops are simultaneously driven to generate a magnetic field, it is impossible to distinguish which loop is responsible for the strength of the magnetic field detected by the magnetic field detector.

The present invention makes it possible to know which loop is generating a magnetic field in a magnetic field generator consisting of multiple loops, thereby improving the accuracy of detecting the position of an underground excavator based on the detection signal of the magnetic field detector. The purpose of the present invention is to provide a position detection device for an underground excavator that can perform the following operations.

[Means for Solving the Problems] In order to achieve the above object, the position detection device for an underground excavator according to the present invention has a position detecting device that detects the position of the underground excavator at the tip of the underground excavator or the reference point in front of the underground excavator. The magnetic field generator provided at one of the positions is composed of a plurality of rectangular loops arranged in parallel, and the adjacent loops are arranged overlapping each other, and each of the above-mentioned loops is arranged at a different position. a power source that excites at a frequency that is excited at a certain frequency; a magnetic field detector that is provided at the other of the tip of the underground excavator and the reference position and that detects the magnetic field generated by each of the loops; When a signal is input, a filter that passes a detection signal of a frequency corresponding to the frequency that excites the loop, and at least one of the magnetic field detector and the magnetic field generator are advanced, and the two are propelled toward each other. and a position calculator that calculates the relative position of the underground excavator with respect to the reference position based on the forward distance of the propulsion machine and the detection signal passed through the filter. .

The position calculator can be provided with a control section that switches the center frequency of the filter.

[Function] In the present invention configured as described above, at least one of the magnetic field generator and the magnetic field detector is advanced by the propulsion device,
A magnetic field ordering device and a magnetic field detector are brought close to each other. Then, each loop of the magnetic field generator is excited at a different frequency while the two are brought close to each other, and the strength of the magnetic field generated by each loop is detected by a magnetic field detector. From the detection signal of this magnetic field detector, only the signal corresponding to the IIJM1 frequency of the loop is extracted by a filter, and the 1-position calculator inputs it to the position calculator. Based on the input detection signal of the magnetic field detector,
Detects the loop that generates the magnetic field that outputs the largest detection signal, determines the offset position of the magnetic field detector with respect to this loop, calculates and outputs the vertical and horizontal deviations from the reference position of the underground excavator. do. Further, the position calculator calculates the distance between the underground excavator and the reference position from the distance traveled by the propulsion machine.

Therefore, the distance to the reference position of the underground excavator and the center shift of the underground excavator with respect to the reference position can be easily determined, and the relative position of the underground excavator with respect to the reference position can be obtained.

Moreover, the magnetic field generator consists of multiple rectangular loops arranged in parallel, with adjacent loops overlapping each other, each loop having a different excitation frequency, and the detection signal of the magnetic field detector being filtered. Since the frequency corresponding to the excitation frequency of the loop is selected by , it is possible to easily know which loop's magnetic field is responsible for the strength of the detected magnetic field. Moreover, by increasing the ratio between the long side and the short side of the loop, the detection signal of the magnetic field detector that detects the strength of the magnetic field generated by the long side is
The effect of the magnetic field generated by the short side can be ignored, and the accuracy of position detection can be improved, which is not the same effect as detecting the strength of the magnetic field generated from a substantially infinitely long parallel conductor. Even if the distance between the long sides of each loop is reduced to increase the ratio of the long side to the short side, the magnetic field detector can be separated from the magnetic field generator by adjusting the number of loops appropriately. Therefore, it is possible to prevent a decrease in detection accuracy.

In addition, if the position calculator is provided with a control unit that switches the center frequency of the filter, and the center frequency is switched to the one that corresponds to the excitation frequency of the loop, and the detection signal acquisition timing is synchronized with this switching, the input detection signal It is easy to find out which loop's magnetic field is responsible for this.

〔Example〕

A preferred embodiment of the position detection device for an underground excavator according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram of a position detection device for an underground excavator according to an embodiment of the present invention.

In FIG. 1, an underground excavator 10.20 has a cutter drum 12.22 with a cutter not shown. This cutter drum 12.22 is rotatable and
It can be stopped at any rotational position. Also, underground excavation $110.20 is for Canter Drum 1
By moving forward while rotating the cutter drum 12.22, the earth and sand excavated by the cutter drum 12.22 is taken into the cutter drum 12.22 and transported rearward by a screw conveyor or the like. And these underground excavators l0
120 excavates from different starting shafts in directions approaching each other along the tunnel planning line, and connects the excavated tunnels.

At the front of one underground excavation tR20, small diameter poling devices 24a, 24b, and 24c of consolidation excavation type are provided.

These boring devices 1J 24 a, 24b, 24
c includes magnetic field detectors 26a and 26b whose details will be described later.
, 26c, and serves as a propulsion device for advancing and retracting the magnetic field detectors 26a, 26b, and 26c.

Each boring device 24a, 24b, 24c is provided on the rear side of the cutter drum 22 of the underground excavator 20, and is spaced at 90 degree intervals on a circumference with a radius r relative to the center (origin) of the underground excavator 20. It is located. That is, if the X-axis is in the direction of excavation passing through the center of the underground excavator 20, the Z-axis is in the vertical direction, and the Y-axis is in the direction perpendicular to the X-axis and the Z-axis, each boring device 2
4a, 24b, 24c are (0, 0, r), (0, r,
0), (0, -r, 0).

The cutter drum 22 includes a boring device 24a,
Through holes (not shown) are provided corresponding to the boring devices 24b and 24c, and when the canter drum 22 stops at the standard position, the through holes are located in front of the boring devices 24a, 24b and 24c. Therefore, the polling devices 24a, 24b, 2
4c digs forward from the through hole when the cutter drum 22 stops at the standard position, and detects the magnetic field detectors 26a and 26b.
, 26c can be advanced toward the other underground excavator 10.

On the other hand, the other underground excavator 110 serves as a reference position for the underground excavator 20, and is provided with magnetic field generators 14a and 14b, the details of which will be described later, on the front of the canter drum 12 or inside the canter drum 12. , 14C is provided. These magnetic field generators 14a, 14b, 14c are connected to the underground excavator 20.
The boring devices 24a, 24b, 24c are provided correspondingly, and when the center lines of the underground excavator 10.20 are aligned so that they face each other, and the cutter drum 12.22 is stopped at the standard position, the magnetic field is Detectors 26a, 26b, 26c
The centers of the polling devices 24a, 24b, and 24c coincide with each other.

Each magnetic field generator 14a, 14b, 14c is connected to a power supply device 19.
The magnetic field is connected to the power source 19 and is supplied with power from the power supply device 19 to generate a magnetic field. And each magnetic field generator 14a
, 14b and 14c have the same structure, and as shown in FIG. 2 using the magnetic field generator 14a as an example, they have a structure in which a pair of loop parts 16a and 16b are arranged orthogonally.

Each loop portion 16a, 16b is, as shown in FIG.
Plural, for example, five rectangular loop cables 18a
~18e. Each loop cable 18a-1
8e are arranged in parallel along the long sides, and each adjacent loop cable overlaps each other by half. These loop cables 18a to 18e constitute a power supply device 19, each of which is connected to an AC source 19f, ~19f, with a different output frequency, and independently generates an AC magnetic field with a different frequency. ing.

Note that the loop cable 1 constituting the loop portion 16a
8 a-18e is arranged so that its long side is parallel to the Z axis of the underground excavator 110, and the loop cables 18a to 18e forming the loop portion 16b are arranged so that their long sides are parallel to the Z axis of the underground excavator 10. It is arranged parallel to the Y axis.

On the other hand, the magnetic field detectors 26a, 26b, and 26c each include a Y-axis direction detection section 28a and a Z-axis direction detection section 28b, as shown in FIG. 2 by taking the magnetic field detector 26a as an example. Further, the Y-axis direction detection section 28a and the Z-axis direction detection section 28b each include a pair of detection coils arranged orthogonally, and output a detection signal corresponding to the strength of the magnetic field detected by each detection coil. That is, the detection coil of the Y-axis direction detection section 28a detects the strength of the magnetic field generated by the loop section 16a, and the detection coil of the Z-axis direction detection section 28b detects the strength of the magnetic field generated by the loop section 16b. Each of them outputs a detection signal corresponding to the strength of the magnetic field. The detection signals of each magnetic field detector 26a, 26b, 26c are transmitted to the position calculator 30 via filter devices 42a to 42c.
(see Figure 1).

As shown in FIG. 4, the filter devices 42a to 42c are composed of bandpass filters 44a and 44b, and a Y-axis direction detection section 28a or a Z-axis direction detection section 28b is provided on the input side of these bandpass filters 44a and 44b. Detection coils 46a and 46b constituting the sensor are connected. Further, the bandpass filters 44a and 44b are connected to the control section 32 of the position calculator 30, so that the center frequency of the filters can be changed by receiving a control signal from the control section 32.

The position 1 arithmetic unit 30 includes a control section 32 and a signal processing section 34, and the signal processing section 34 receives a timing signal from the control section 32 to control each magnetic field detector 26a, 26b, 26.
The detection signals of underground excavation I! 20 underground excavation [relative distance to 10, offset position in Y-axis direction and Z-axis direction, axis of underground excavation 9110 (X
The pitching angle and rolling angle with respect to the axis) are calculated and output to the display device 36 for display (see FIG. 1).

Underground excavation according to the embodiment configured as described above [10, 20
The relative position between them is determined as follows.

First, cutter drum 12.2 for underground excavation l110.20
2 is stopped at the standard position. Next, drive the polling devices 24a, 24b, 24c provided in the underground excavator 20,
The excavation is continued until the tips of each reach the front of the underground excavator 10, which serves as a reference position, and the magnetic field detectors 26a, 26b,
26C is brought close to the magnetic field generators 14a, 14b, and 14c. The fact that the tip of each polling device 24a, 24b, 24c has reached the front of the underground excavator 10 is detected by the magnitude of digging resistance, etc., and each polling device 24a'b
The excavation distances 24b and 24c are input to the position calculator 3°.

The magnetic field detectors 26a, 26b, 26c are the magnetic field generator 14a
, 14b, 14c, the power supply 1
Turn on each AC amount 1ffl 9 f, ~19f1 of 9,
Loop portion 16a of each magnetic field generator 14a, 14b, 14C
Or the loop cable 1 constituting the loop portion 16b
8a to 18e to generate alternating magnetic fields with different frequencies.

The Y-axis direction detection section 28a of the magnetic field detector 26a detects the strength of the magnetic field from the loop cables 18a to 18e that constitute the loop section 16a of the magnetic field generator 14a, and detects the strength of the magnetic field according to the strength of the detected magnetic field. The detection signal is input to the filter device [42]. That is, detection signals from detection coils 46a and 46b forming the Y-axis direction detection section 28a are manually input to bandpass filters 44a and 44b.

The bandpass filters 44a and 44b are connected to the position calculator 300.
! The center frequency is set by the Ili section 32 to the AC power source 19f.
, ~19f, are sequentially changed to match the output frequencies of . The detection signals that have passed through the bandpass filters 44a and 44b are amplified by amplifiers 48a and 48b, and sent to the signal processing section 34 of the position calculator 30.

The signal processing unit 34 and the control unit 32 include a band pass filter 44.
The frequency selection signal output to the amplifiers 48a and 44b is received as a detection signal capture signal, and the detection signals output by the amplifiers 48a and 48b are read in synchronization with this capture signal, and each detection signal is compared with each other to determine which signal has the highest signal level. Select a signal. Then, the position calculator 30 detects the loop cable 18i that is generating the magnetic field detected by the Y-axis direction detection unit 28a, and detects the highest level signal of the loop cable 18i.
The detected position of the loop cable 181 with respect to the center of is calculated.

By the way, as mentioned above, the AC power supplies 19f1 to 19f
, have different output frequencies, and the loop cable 18
The magnetic field generated by a-18e is also an alternating magnetic field with different frequencies. Therefore, magnetic field detectors 26a, 26b, 26c detect the strength of the magnetic field by the induced electromotive force of the detection coil.
The magnitude of the detection signal changes depending on the frequency of the magnetic field generated by the loop cables 18a to 18e.

For example, as shown in Fig. 5, a loop cable A with a width of 28,
B and C are respectively f (=276 le) and 2f (=552
Hz), 3f (=828 Hz), the detection signals due to the magnetic fields generated by the respective loop cables A, B, and C are as shown in FIG. Therefore, when loop cables A, B, and C are excited simultaneously, if an attempt is made to detect loop cable 1B+ only by the magnitude of the detection signal, the magnetic field detector detects loop cable A Even if it is within the range, the strength of the detection signal due to the magnetic fields of loop cables B and C may be greater, making accurate detection difficult. Therefore, the magnetic field generated by each loop cable is made to have a magnitude inversely proportional to the excitation frequency, and the detection signal output by the magnetic field detector is made to be inversely proportional to the excitation frequency.

By doing this, the intensity distribution of the detection signal is
As shown in the figure, the intensity of the detection signal that has passed through the band-pass filters 44a and 44b becomes as shown in Figure 8, making it easy to know which loop cable's magnetic field has the highest level of detection signal. , make sure to loop cable 18
i can be specified.

This loop cable 18 to the center of the loop portion 16a
The i position is determined as follows.

For example, if the loop portion 16a is made up of five loop cables 18a to 18e as shown in FIG. cable 1
Distance 111 between the center of 8c and the center of loop cable 18d
[f] is determined and stored in a storage unit (not shown). after that,
The position calculator 30 calculates the deviation δy of the y-axis direction detection unit 28a with respect to the center of the loop cable 18e according to Japanese Patent Application No. 165352 or Japanese Patent Application No. 12230 filed by the present applicant.
Calculated based on the calculation formula shown in No. 35. and,
The position calculator 30 is connected to the loop section 1 of the Y-axis direction detection section 28a.
The deviation dy from the center of 6a, i.e. the polling device 2
How far the center of the magnetic field generator 14a is deviated in the Y-axis direction with respect to the center of the magnetic field generator 14a is determined by the following equation.

ay=-δy ” f y --- (1) Then, the position calculator 30 similarly calculates each polling device 2
4a, 24b, 24c magnetic field generators 14a, 14b, 1
4c from the center in the Y-axis direction and the Z-axis direction, calculate and display the deviation position and direction of deviation of the center of the underground excavator 20 with respect to the center of the underground excavator 10. Displayed on the device 32.

Further, the position calculator 30 calculates the distance between the underground excavator 2 The pitching angle and rolling angle for underground excavation 1!10 are determined and displayed on the display device 32.

Thus, in the embodiment, the magnetic field generators 14a, 1
4b and 14c are rectangular loop cables 18a to 18e.
By configuring each loop cable 18a
By increasing the ratio (long side/short side) of the long side and short side of ~18e, the magnetic field generated by the short side of loop cables 18a~18e is Underground excavation [120
The accuracy of detecting the offset position of the underground excavator 10 can be improved. Moreover, a plurality of loop cables 18a~
18e is a band-pass filter 44a in which adjacent loop cables are arranged in parallel along the long side and overlapped in halves, and have different excitation frequencies.
, 44b to extract a detection signal corresponding to the excitation frequency, the loop cables 18a to 1
Even if 8e are excited at the same time, it is possible to easily identify the loop cable that is generating the magnetic field with the largest detection signal. Further, even if the distance between the long sides of the loop cable is narrow, by arranging the number of loop cables according to the expected amount of firing deviation, it is possible to easily secure the necessary detection range.

In the embodiment described above, the magnetic field detector 26 is moved forward by the polling device 24, but the magnetic field generator 14 may be moved forward, or both the magnetic field generator and the magnetic field detector 26 may be moved forward. Also, in the above embodiment, two underground excavators @
Although the case of joining according to 10.20 has been described, for example, it can also be applied when the poling device 24 for advancing the magnetic field detector 26 is placed in a reaching shaft and the position of an underground excavator with respect to this reaching shaft is determined. can. and,
In the embodiment described above, a case has been described in which the small-diameter compacted poling device F24 is used as the propulsion device for advancing the magnetic field detector 26, but the propulsion device is not limited to this.

Furthermore, in the above embodiment, a case was explained in which a plurality of magnetic field generators and a plurality of polling devices were provided, but either one or both of them may be set to one, and these may be rotated to position them with respect to the underground excavator. The measurement may be performed by changing the .

〔Effect of the invention〕

As explained above, according to the present invention, the position calculator calculates the distance between the underground excavator and the reference position from the distance traveled by the propulsion machine, and also calculates the distance between the underground excavator and the reference position from the detection signal of the magnetic field detector. Calculate and output the vertical and horizontal deviations of the excavator from the reference position.

Therefore, the distance to the reference position of the underground excavator and the eccentric position of the underground excavator with respect to the reference position can be easily determined, and the relative position of the underground excavator and the reference position can be obtained.

Moreover, the magnetic field generator is configured with multiple rectangular loops, each of which is excited at a different frequency, and
Since the filter extracts the detection signal corresponding to the excitation frequency of the loop, even if a plurality of loops are excited simultaneously, the loop containing the largest detection signal can be easily identified. By increasing the ratio of the long side to the short side of the loop, the magnetic field to be detected can ignore the influence of the magnetic field generated by the short side, and is essentially the same as the magnetic field generated from an infinitely long parallel conductor. The same effect as detecting strength can be obtained, and the accuracy of position detection can be improved.

Even if the distance between the long sides of each loop is reduced to increase the ratio of the long side to the short side, the magnetic field detector can be does not come off from the magnetic field generator, and a decrease in detection accuracy can be prevented.

Further, if the center frequency of the filter is changed by the control section of the position calculator, the loop can be more easily performed by synchronizing the change of the center frequency and the acquisition of the detection signal.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of a position detection device for an underground excavator according to an embodiment of the present invention, Figure 2 is a partially enlarged diagram of the embodiment, Figure 3 is a detailed diagram of the magnetic field invention, and Figure 4 is a detailed diagram of the magnetic field invention. The figure is a block diagram of the circuit that processes the detection signal of the embodiment, Figure 5 is a layout diagram of the loop cable to explain the relationship between the excitation frequency and the detection signal, and Figure 6 is the loop cable shown in Figure 5. Fig. 7 is an explanatory diagram of the intensity distribution of the detection signal when the strength of the magnetic field is adjusted, and Fig. 8 is a band pass diagram of the detection signal with the intensity distribution shown in Fig. 7. A diagram showing the intensity after passing through a filter, Figure 9 is a diagram showing the relationship between the deviation position obtained by measuring the magnetic field from a parallel conductor that can be considered to be of infinite length, and the measured deviation, and Figure 10 is a diagram showing the relationship between the actual deviation of the rectangular loop. FIG. 7 is a diagram showing the error of the offset position obtained by measuring the magnetic field with respect to the actually measured amount of deviation with respect to the change in the ratio of the long side and the short side. lO120----1 underground excavator, 14a ~ 14cm
・−・・−Magnetic field generator, 16a, 16b ・−・−・・
Loop ridges 18a to 18e --- Loop cable, 19 --- Power supply device, 24 a to 24
c ----- Single propulsion machine (poling device), 2
6 a to 26 c--magnetic field detector, 30--position calculator, 32 -----1 control section, 34-- signal processing section, 42a to 42cm-filter device, 44a144b-
・−・Band pass filter.

Claims (2)

[Claims] (1) The magnetic field generator installed at either the tip of the underground excavator or the reference position in front of the underground excavator is composed of a plurality of rectangular loops arranged in parallel, and a power source for energizing each of the loops with a different frequency; and a power supply provided at the other of the tip of the underground excavator and the reference position; a magnetic field detector that detects the magnetic field generated by each of the loops; a filter into which the detection signal of the magnetic field detector is input and that passes a detection signal of a frequency corresponding to the frequency that excited the loop; a magnetic field detector; A propulsion device that moves at least one of the magnetic field generator forward and brings them closer together. Based on the forward distance of this propulsion device and the detection signal that has passed through the filter, the relative position of the underground excavator to the reference position is determined. A position detection device for an underground excavator, comprising: a position calculator for calculating a position; and a position detecting device for an underground excavator. (2) The position detection device for an underground excavator according to claim 1, wherein the position calculator has a control unit that switches the center frequency of the filter.