JPH01172701A - Excavation machine position detection device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a method for detecting the position of an excavator underground in order to make the excavator excavate underground along an excavation target line. This invention relates to a detection device.

[Conventional technology]

When burying pipes, etc. underground without excavation using the small-diameter excavation method, etc., the excavator placed at the tip of the pipe must excavate underground along a predetermined excavation target line. .

For this reason, it is necessary to detect the position of the excavator underground and correct it if the excavator deviates from the excavation target line. In this way, detecting the position of the excavator is an essential means when excavating underground to construct a tunnel or burying a sewer pipe or the like. Hereinafter, conventional position detection means will be explained with reference to the drawings.

FIG. 4 is a schematic diagram of the configuration of a conventional position detection device. In the figure, A indicates the ground surface, A' indicates underground, and T indicates the excavation target line. 1
is an AC power source, and 2a and 2b are conductive wires. Conductor wires 2a, 2b
are loop-shaped conducting wires arranged at equal intervals W (W=W, =W,) from the excavation target line T, and are connected to each other on the side opposite to the power supply l. Reference numeral 3 denotes an excavator which is located underground A' and is made to excavate in the direction of arrow 4 along the excavation target line T. 5a and 5b are magnetic field detectors arranged on both sides of the excavator 3. Note that x, y, and z indicate assumed coordinate axes.

Now, when a current is supplied to the conductors 2a and 2b by the power supply l,
The magnetic field formed underground by this current is
When the length of b in the X-axis direction is sufficiently long, it changes as a function of the distance (depth) y in the Y-axis direction and the distance X in the X-axis direction. Therefore, if the magnetic field is detected by the magnetic field detectors 5a and 5b, the position of the excavator 3 in the underground A' can be detected.

When the magnetic field detectors 5a, 5b are constituted by loop coils, the output thereof is proportional to the temporal rate of change of the magnetic flux passing through the loop surface of the coil. Here, φ: Magnetic flux passing through the loop surface of the coil N: Number of turns of the coil G: Loop area of the coil B: Magnetic flux density passing through the loop surface of the coil ω: Frequency of the magnetic flux, then the output e of the loop coil is as follows. It is expressed by the formula.

e=dφ/dt=ω・N-G-B-cosωt−・−・
--- (1) Also, when current is supplied to the conductors 2a and 2b, the magnetic field H in the X-axis direction, and the magnetic field 1-17 in the Y-axis direction are the positions of the excavator 3. When WX and y are determined as shown, they are expressed by the following equation.

・・・・−・−−−・・−−−−・−・・(2)−−−
−−・−・−−−−・・−・・−・(3) Furthermore, the relationship between the magnetic field H and the magnetic flux density B is as follows, where μ is the magnetic permeability of the material, B=μ・H−・・−・・・−・−・・・・・・−・・(4
). In this embodiment, the medium is soil, and the magnetic permeability of soil can be kept constant, with almost no difference from air.

From the above, the positions x and y of the excavator 3 can be calculated based on the outputs e of the magnetic field detectors 5a and 5b. And, such means determines what kind of excavation target line T is iv! Since the position of the excavator 3 in the underground A' can be continuously detected even if it is a straight line or a curve, the excavator 3 can be automatically controlled.

[Problem that the invention seeks to solve]

By the way, when excavating by the above-mentioned means,
If there is an unknown obstacle made of iron-based materials in the soil,
The passage of magnetic flux generates eddy currents in this obstacle, which change the magnetic field in the soil. For this reason, the magnetic field detector 5
The detected values of a and 5b also change significantly compared to the detected values when such an obstacle does not exist. As a result, once excavation is performed in the wrong direction based on an erroneous detected value, it is not easy to correct this, and in extreme cases, there is a risk that the excavation will be carried out in a large meandering manner.

An object of the present invention is to solve the above-mentioned problems of the prior art, to reliably detect obstacles that disturb magnetic flux in the ground, and to prevent erroneous position detection. and, in turn, provide a device for detecting the position of the target excavator.

[Means for solving problems]

In order to achieve the above object, the present invention includes an excavator, a loop-shaped conducting wire arranged along an excavation target line of the excavating machine, and a magnetic field caused by a current attached to the excavating machine and supplied to the conducting wire. In the position detection device for an excavator, the position detection device includes a first magnetic field detector and a second magnetic field detector that detect a magnetic field. another conducting wire, a calculation means for calculating the position of the excavator based on the detection value of each of the magnetic field detectors and the predetermined interval between each of the conducting wires, and each of the magnetic field detectors obtained for each of the conducting wires. The invention is characterized by further comprising an obstacle detection means for comparing the product of a value obtained by subtracting each of the sum and difference ratios of the detected values and a value determined by the excavator with the predetermined interval.

[For production]

Before the calculating means calculates the position of the excavator, the obstacle detecting means detects the presence or absence of an obstacle. This detection is performed as follows. That is, the magnetic field generated by one of the conductive wires is detected by each magnetic field detector, the sum and difference of each detected value are calculated, and the ratio of the sum and the difference is determined. Similarly, calculate the ratio of the sum and difference of each detected value of the magnetic field generated by the other conductor. Next, calculate the subtracted value of each of these values, and multiply the subtracted value by a predetermined value determined by the excavator. Compare with the interval. If the two values are approximately equal, it is determined that no obstacle exists; otherwise, it is determined that an obstacle exists.

〔Example〕

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 is a schematic diagram of the configuration of a position detection device according to the present invention. In the figure, parts that are the same as those shown in FIG. 4 are given the same reference numerals, and description thereof will be omitted. 20a and 20b are the conductor wires 2 shown in FIG.
Similar to a and 2b, a loop-shaped conducting wire 21a is laid at equal intervals W with respect to the excavation target line T.

Reference numeral 21b indicates a loop-shaped conductive wire installed at a predetermined distance S from the conductors 20a and 20b, and 6 indicates a changeover switch interposed between the power source 1 and each of the conductive wires 20a, 20b, 21a, and 21b. Although not shown, magnetic field detectors 5a, 5
An arithmetic device for inputting the detected value of b is installed at an appropriate location on the ground surface A or the like. Note that a loop coil is used for the magnetic field detectors 5a+5b. F indicates an obstacle made of iron-based members existing in the soil.

Next, the operation of this embodiment will be explained with reference to FIGS. 2(a) and 3(b) and FIG. 3. FIG. 2(a) is a sectional view taken along line I[a-na shown in FIG. 1, and the same parts as shown in FIG. 1 are given the same reference numerals. Changeover switch 6
When switched to conductors 20a and 20b, conductor 20a.

A current is supplied to 20b, and a magnetic field as shown by the solid arrow 7 is formed underground A' by this current.

The magnetic field detectors 5a and 5b detect only the magnetic field component in the X-axis direction in such a magnetic field.

First, position detection when the obstacle F does not exist will be described. When the excavator 3 is made of non-magnetic or non-conductive material, the X-axis direction component H of the magnetic field (magnetic flux density) is the center of the conductors 20a and 20b (excavation target line T)
The magnetic field component H becomes zero immediately below , and as it deviates from this position in the X-axis direction.

changes. In this case, when the deviation in the X-axis direction is small compared to the depth y and the distance 2W, the size of the deviation and the magnetic field component H,
There is a proportional relationship between FIG. 2 [b] is a characteristic diagram showing this, in which the horizontal axis represents the magnitude of deviation X, and the vertical axis represents eight magnetic flux densities. Conductive wires 20a, 20b
The characteristic when a current is supplied to is shown by the straight line B2°, and the output of the magnetic field detector 5a is a value proportional to the magnetic flux density Btus, and the output of the magnetic field detector 5b is a value proportional to the magnetic flux density B2°5. Become.

From the above state, when the changeover switch 6 is switched and current is supplied from the power source 1 to the conductors 21a and 21b, the magnetic field pattern indicated by the arrow 7 in FIG. Its characteristic also moves by a distance S as shown by the broken line BZ+ in FIG. In this case, the outputs of the magnetic field detectors 5a and 5b are respectively magnetic flux densities Bzl,...
The value is proportional to B zlb.

By the way, as mentioned above, the excavator 3 is often made of iron-based materials, so due to the effects of eddy currents etc.
The position where the axial component H, becomes zero is a position shifted from the position shown in Fig. 2 (al). This is shown in Fig. 3. Fig. 3 is a cross-sectional view similar to Fig. 2 (a). Each part is given the same reference numerals as in Figure 2 (al). As shown, the magnetic field indicated by arrow 7 is biased towards the excavator 3 in the vicinity of the excavator 3, and the magnetic field detector 5b The position where the output becomes zero is a position shifted to the left from directly below the excavation target line T. This shift is indicated by the distance U. Conversely, the position where the output of the magnetic field detector 5a becomes zero is a distance to the right from directly below the excavation target line T. It will be shifted by U.

Considering the above, the output of the magnetic field detector 5a when a current is supplied to the conductors 20a and 20b, ess! . and the output e 5b-26 of the magnetic field detector 5b, and the conducting wire 21
a.

The output e Sa of the magnetic field detector 5a when current is supplied to 21b, and the output e sb of the magnetic field detector 5b,
The expression t+ is as follows. However, k is a proportionality constant, and r is each magnetic field detector 5a from the center of the excavator 3.

5b.

e ss-! O=k+(x+r+u)
−−−−−−−−−−−−t5) esb, zo=+(X r u)−−−−−−−−−−・・
−−−−−(6165m−21=k +(X + r
S + u) −”−−・−−−−−−<7)e
,b-z+ =to+(x-r S u)'-
---"---------"' (sl These outputs e
Ss, Nor e Sb, ta,” S1).!l+
e 5b-1) is input to the aforementioned arithmetic unit (not shown).

In the above equations (5) to (8), the unknown value is kl +
X+U, and the value to be sought is X. Therefore, first, from equations (5) and (6), e 5a-2085h-20r +u e Ss・10 85b-20 −−−−−−−・・−−−−−−・QO) or,
From equations (7) and (8), esa・z+ + esb-t+
X Se sm・t+ e 5b-z
+ r + ue 51-21 -e
1b-1) −−−−−−・・−・−・・−−− Subtracting U2 from the equation αω gives Sm (r0u)・・・−・−・・−・−・−・−−−−・−01r +
u= e St10 e 5b40 e 514
1 e 5b41-----～・--111・・-
--・-・αaIf (r+u) of formula 041 is substituted into formula 01, the position X becomes the known value e sa, Nor e sb,
It can be determined by Nor e sm-zx e ,b,z,,S. In the arithmetic unit, e Sa・N
o + e Sb-! Oe 5s-21”e 5
b-21658-2065b-16e Sm, 21
e 5b-21-・-----1----...
---...09 will be calculated. Thereby, the position (shift) X of the excavation advance a3 from the excavation target line T in the X-axis direction can be detected.

The detection of the position of the excavator 3 when the obstacle F does not exist has been described above. By the way, as described above, when the obstacle F exists, the magnetic field is disturbed and the detected position X becomes an incorrect value, and if the excavator 3 is controlled based on this, an error will occur in the excavation. In order to prevent this, in this embodiment, the arithmetic unit is provided with obstacle detection means for detecting the presence or absence of a faulty vAF. The obstacle detection means will be explained below with reference to the characteristic diagram shown in FIG. 2(b).

In this figure, the curve B2°, indicated by the - dotted chain line, is shown in Figure 2 (a
If an obstacle F as shown in l is present, the conductor 20
This is a characteristic curve of the magnetic flux density of the magnetic field created by a and 20b, and is also a curve B shown by a dotted line. IF is a characteristic curve of the magnetic flux density of the magnetic field created by the conducting wires 21a, 21a when the obstacle F is present. Each of these curves B! OF+82□
are curves obtained through experiments.

When the obstacle F exists in this way, the guide 'fIA20a
.

Magnetic field detectors 5a and 5b when a magnetic field is formed in 20b
The magnetic flux density at B2゜mF, B zo
by, and signals proportional to these magnetic flux densities are output from the magnetic field detectors 5a and 5b. The signal output from the magnetic field detector 5a at this time is assumed to be esm, 2°7, and the signal output from the magnetic field detector 5b is assumed to be esb-2°. On the other hand, when a magnetic field is formed by the conducting wires 21a and 21b, the magnetic flux density in the magnetic field detectors 5a and 5b is 82 as shown in the figure.
1aF+B tlbF, and the signals of the magnetic field detectors 5a and 5b at this time are respectively "S1)'21F+
eSb,! IF.

Here, we will pay attention to the above-mentioned formula 01. α Shu style is an obstacle F
does not exist, the value determined by the excavator 3 (r+u
) and the output signals of the magnetic field detectors 5a and 5b.
) is always equal to the distance S. However, if an obstacle F exists, the characteristic curve becomes the one shown in Figure 2 (bl), and the magnetic flux density with respect to the position arise.

(r+u)・85120F e 5b-20F e
Sll! 1F e 5b-ZIF=S+δ
・・〜−−−−−・−・・・・・
...-αe, that is, calculate the sum and difference of the outputs of the magnetic field detectors 5a and 5b when a magnetic field is formed by the conducting wires 20a and 20b to find the ratio of the two, and also form a magnetic field by the conducting wires 21a and 21b. Calculate the sum and difference of the outputs of the magnetic field detectors 5a and 5b when
By multiplying this difference value by a known value (r+u), if the product is approximately equal to the distance S, it can be determined that the obstacle F does not exist; otherwise, it can be determined that the obstacle F exists. can be judged.

Since the calculation of the above-mentioned "difference in ratio" is obtained in the calculation process for determining the position be able to. If an obstacle is detected, the operator of the excavator 3 can either move the excavator straight for a predetermined period of time while maintaining the state it was in when the obstacle was first detected, or check what the obstacle is. Take appropriate measures such as:

In this way, in this embodiment, the magnetic fields generated separately by the two conductive wires are detected by the two magnetic field detectors, and the ratio of the sum and difference of the detected values of each magnetic field detector for each conductive wire is calculated. The product of this difference multiplied by a predetermined value is compared with the interval between each conducting wire, so the presence of an unknown obstacle can be easily detected. Furthermore, since the above comparison is performed for each calculation, it is possible to prevent erroneous position detection and to prevent excavation from deviating from the target line.

In the above embodiment, an example in which obstacle detection is performed every time a position detection calculation is performed has been described, but it goes without saying that obstacle detection may be performed every predetermined number of calculations. or,
In the above comparison, an example was explained in which the product of the value (r+u) and the "ratio difference" of the detection value of each magnetic field detector is compared with the conductor spacing. ) can also be compared, and both mean the same operation. Further, if the excavator is made of non-magnetic material, the value U is 0. Furthermore, as the magnetic field detector, a Hall element or the like can be used in addition to the coil.

〔Effect of the invention〕

As described above, in the present invention, the magnetic fields generated separately by two conductive wires are detected by two magnetic field detectors, and the ratio of the sum and difference of the detected values of each magnetic field detector for each conductive wire is determined. Since the product obtained by multiplying the subtracted value of the ratio by a predetermined value is compared with the conductor spacing, it is possible to easily detect the presence or absence of an obstacle, prevent incorrect position detection, and improve excavation. can be prevented from being carried out off the target line.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the configuration of a position detection device according to an embodiment of the present invention, FIG. 2 (al is a sectional view taken along the line IIa-Ila shown in FIG. 1, and FIG. Fig. 3 is a cross-sectional view explaining the polarization of the magnetic field, Fig. 4 is a characteristic diagram of the device shown in Ill.
The figure is a schematic diagram of the configuration of a conventional position detection device. DESCRIPTION OF SYMBOLS 1... Power supply, 3... Excavation machine, 5a, 5b... Magnetic field detector, 6... Switch, 20a, 20b, 21a,
21b-conductor, T... excavation target line. 3. Drilling box 5a, 5b: Magnetic field enhancer 20a, 20b, 21a, 2 lb: 4 cylinders Fig. 2 (a) Fig. 3

Claims (2)

[Claims] (1) An excavator, a loop-shaped conductive wire arranged along the excavation target line of the excavator, and a first magnetic field detector attached to the excavator and detecting a magnetic field caused by the current supplied to the conductor. and a second magnetic field detector, a loop-shaped other conducting wire arranged at predetermined intervals along the conducting wire and to which current is supplied, and a detection value of each of the magnetic field detectors. and a calculation means for calculating the position of the excavator based on the predetermined interval between each of the conductive wires, and subtracting the ratio of the sum and difference of the detected values of each of the magnetic field detectors obtained for each of the conductive wires. A position detecting device for an excavator, characterized in that it is provided with obstacle detection means for comparing the product of the value determined by the excavator and the value determined by the excavator with the predetermined interval. (2) In claim (1), the value determined by the excavator in the obstacle detection means is determined by the distance from the center of the excavator to each of the magnetic field detectors and the material of the excavator. 1. A position detection device for an excavator, characterized in that the detection value is the sum of the amount of deviation of a magnetic field.