JPH0525048B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for excavating underground with an excavator,
The present invention relates to a position detection device for an excavator that detects the position of an excavator in order to cause the excavator to dig along an excavation target line.

[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 and burying a pipe. Hereinafter, conventional position detection means will be explained with reference to the drawings.

FIG. 5 is a sectional view of a conventional position detection device.
In the figure, 1 is the excavator digging underground, and 2 is the excavator 1.
A buried pipe 3 provided at the rear of the excavator 1 is a starting shaft for the excavator 1 to start digging. A pushing device (not shown) for pushing the rear part of the buried pipe 2 is provided in the starting shaft 3. 4 is a laser oscillator installed at a proper location in the starting shaft 3. The laser oscillator 4 is configured to emit a laser beam 5 to the excavator 1 through the buried pipe 2. A screen 6 is provided on the excavator 1 and receives the laser beam 5 from the laser oscillator 4. T indicates the excavation target line of the excavator 1.

When the excavator 1 is excavating on the excavation target line T, the laser beam 5 is received at a predetermined location on the screen 6, but when the excavator 1 is excavating on the excavation target line T
When the laser beam 5 deviates from the predetermined location, the laser beam 5 also deviates from the predetermined location. A deviation of the excavation machine 1 from the excavation target line T is detected by the deviation of the laser beam 5 on the screen 6, and the trajectory of the excavation machine 1 is thereby corrected.

However, the above method has the disadvantage that when the excavation target line T is curved (in the case of curved construction), the laser beam 5 does not reach the screen 6, so the position deviation of the excavation machine 1 cannot be detected. In addition, when the diameter of the shield tunneling machine 1 is small (for example, the diameter is about 100 mm), the passage of the laser beam 5 can be secured by various devices arranged inside the tunneling machine 1 and the buried pipe 2. It also had the disadvantage that it was impossible to do so. In order to eliminate such drawbacks, the following measures have been proposed.

FIG. 6 is a sectional view of another conventional position detection device. In the figure, the same parts as in FIG. 5 are given the same reference numerals. 7 is a magnetic field generator provided in the excavator 1;
8 is a magnetic field detector that detects the magnetic field generated by the magnetic field generator 7; 9 is a surveying device that measures the position of the magnetic field detector 8 on the ground; 10 is a device that inputs the position signal of the magnetic field detector 8 from the surveying device 9; , is a control unit that controls the excavation direction of the excavator 1 based on this.

When the N and S poles of the magnetic field generator 7 are on a vertical line, the magnetic field strength in the vertical direction is maximum (or the magnetic field strength in the horizontal direction is minimum) at a point directly above the magnetic field generator 7 on the earth's surface. Therefore, if the magnetic field detector 8 is moved (scanned) on the earth's surface to search for a point where the magnetic field strength is maximum (or minimum), the other point will be a point directly above the magnetic field generator 7. Then, if the position of the magnetic field detector 8 is measured with the surveying device 9, the excavator 1
can detect the position of

[Problem to be solved by the invention]

However, although such a device can eliminate the above-mentioned conventional drawbacks, on the other hand, it scans the magnetic field detector 8 on the ground surface to search for the position of the excavator 1, and then scans the magnetic field detector 8. The position must be surveyed, which not only requires a separate surveying instrument, but also has the disadvantage that searching and surveying requires complicated labor and a long time. If we attempt to automate the measurement to eliminate this drawback, an automatic tracking device or the like will inevitably be required to detect the magnetic field and determine the position of the magnetic field detector 8, creating a new drawback of increased costs. was.

Furthermore, when scanning the magnetic field detector 8 on the ground surface as described above, measurements must be made intermittently (for example, to excavate 100 m and take measurements every 50 cm, 200 scans are required). necessary and measurement
It will be intermittent 200 times. ), therefore, there was also a drawback that it was difficult to implement automatic direction control of the excavator 1.

The present invention has been made in view of the above circumstances, and its purpose is to eliminate the drawbacks of the above-mentioned conventional techniques, utilize the space of the subsequent buried pipe, and use measuring instruments and automatic tracking devices. The position of the excavator can be easily and continuously detected without
Moreover, it is an object of the present invention to provide a position detection device for an excavator that can increase the output sensitivity in horizontal position detection and improve detection accuracy.

[Means to solve the problem]

In order to achieve the above object, the present invention provides an excavator for excavating underground, with continuous guide lines arranged at equal intervals from the excavation target line on both sides of the excavation target line of the excavator. , a power source that supplies current to the induction wire and thereby generates a magnetic field;
The tunneling machine is provided with a magnetic field detection device arranged at a target position with respect to the vertical plane of the tunneling machine, and the distance between the guide wires is determined by the vertical distance between the installation surface of the guide wire and the magnetic field detection device. It is characterized by being selected so that it almost matches the distance in the direction.

[Effect]

Guide wires are placed at equal intervals on both sides of the excavation target line, and when current is supplied to the guide wires,
A magnetic field is generated from the guiding wire. This magnetic field is detected by two magnetic field detection devices, and the positional deviation of the excavator is calculated based on the detected values. In this case, the output of the magnetic field detection device can be increased by selecting the spacing between the guide wires so that it almost matches the vertical distance between the surface on which the guide wires are installed and the magnetic field detection device. can.

〔Example〕

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

FIG. 1a is a plan view of a position detection device according to an embodiment of the present invention, FIG. 1b is a sectional view along the excavation target line shown in FIG. 1a, and FIG. 1c is a line C in FIG. 1a. -C sectional view. In the figure, the same parts as those shown in FIG. 5 are given the same reference numerals. Magnetic field detectors 11a and 11b are provided in the excavator to detect a magnetic field, and are composed of coils that generate an induced electromotive force in response to the magnetic field when placed in the magnetic field. 12 is the distance W along both sides of the excavation target line T on the ground surface.
The distance from the excavation target line T to the guide line 12 on one side is equal to the distance from the guide line 12 on the other side. This guide wire 12 is composed of a single conducting wire. A power supply 13 is connected to both sides of the guide wire 12 and supplies alternating current to the guide wire 12. 1
Reference numeral 4 denotes a controller that receives signals from the magnetic field detectors 11a and 11b and performs necessary calculations and controls.

Next, the operation of this embodiment will be explained with reference to the position of the shield tunneling machine and the magnetic field strength characteristic diagram for that position shown in FIGS. 2a and 2b. When current is supplied from the power source 13 to the guide wire 12, the guide wire 12
A magnetic field is formed around the magnetic field, and this magnetic field is detected by magnetic field detectors 11a and 11b. Here, I: Current supplied from the power supply 13 to the induction wire 12 I ₀ : Maximum amplitude of the current I ω: Angular frequency of the current I H _x : Magnetic field strength of the x-direction component generated on the X-axis (described later) y : Installation surface with guide wire 12 and magnetic field detector 11
a, 11b, where W is the distance between the guide wires 12, the current I and the magnetic field strength _Hx are expressed by the following equation.

I=I _0sio 〓 _t H _x =Iy/2π{1/(x+W/2)
+y ² -1/(x-W/2)+y ² } Figure 2a is a diagram showing a state in which the excavator 1 is at a position (positional deviation δ) deviated from the excavation target line T.
A line connecting the magnetic detectors 11a and 11b is set on the X-axis. Note that the distance between the center F of the excavator 1 and each magnetic field detector 11a, 11b is indicated by r. Figure 2b shows the distance y and the distance W between the guide lines 12.
The magnetic field strength H _x when is equal (y=W)
is a diagram showing the characteristics of
Also, the magnetic field strength H _x is plotted on the vertical axis. As is clear from the figure, the magnetic field strength H _x is
It becomes 0 at the center of , and increases approximately in proportion to the distance as you move away from the center. Incidentally, such characteristics could be confirmed through experiments. Here, k ₁ : proportionality constant x : from the excavation target line T to the magnetic field detectors 11a, 11
Distance to b H _xa : Magnetic field strength detected by the magnetic field detector 11a H _xb : Magnetic field strength detected by the magnetic field detector 11b δ : Displacement (positional deviation) of the excavation machine 1 from the excavation target line T. Approximately, the following formula holds true.

H _x =k ₁ ·x Here, the proportionality constant k ₁ in the above equation will be considered with reference to FIG.

FIG. 3 is a characteristic diagram of the proportionality constant k ₁ . In the figure, the distance W between the guide wires 12 is plotted on the horizontal axis, and the proportionality constant k ₁ is plotted on the vertical axis. The figure shows distance y (depth)
This figure shows the analysis results of the relationship between the line-to-line distance W and the proportionality constant k ₁ in the cases where is 2 m, 3 m, and 5 m.
If we draw a perpendicular line from the peak of the characteristic curve for each distance y (the point where the proportionality constant k ₁ is maximum) to the horizontal axis as shown by the two-dot chain line, the peak when distance y is 2 m will be found when distance W is around 2 m. It can be seen that when the distance y is 3 m, the peak is near the distance W of 3 m, and when the distance y is 5 m, the peak is near the distance W of 5 to 6 m. As is clear from the above equation, a large k ₁ means that the detection sensitivity of the magnetic field is large, so in the end, the distance W between the guide wires 12 is almost equal to the distance y (depth). If arranged in this manner, position detection can be performed with high sensitivity. Therefore, measurement can be performed with a large S/N ratio, and position detection accuracy is improved.

Next, regarding the magnetic field strengths H _xa and H _xb , in the magnetic field detector 11a, x=r+δ, and the magnetic field detector 1
1b, since x=r−δ, each magnetic field strength
H _xa and H _xb are as follows: H _xa =k ₁ (r+δ) H _xb =k ₁ (r−δ). Since the electrical signal _Exa output from the magnetic field detector 11a and the electrical signal _Exb output from the magnetic field detector 11b are each proportional to the detected magnetic field strength, the following equation holds true.

_Exa = k ₁ · k ₂ (r + δ) E _xb = -k ₁ · k ₂ (r - δ) In the above formula, k ₂ is a proportionality constant, and this proportionality constant k ₂ is , 11b, where N is the number of turns of the coil, and a is the cross-sectional area of the coil, k ₂ ∞N·a·ω.

From the above, to find the positional deviation δ of the shield tunneling machine 1, calculate _Exa + _Exb / _Exa - _Exb = δ/r. Since the value r is a constant value, the positional deviation δ can be calculated as follows. You can ask for it. The controller 14 outputs the output signal _Exa of the magnetic field detector 11a and the magnetic field detector 11b.
The output signal E _xb of is input, and the above equation is calculated based on these values to calculate the positional deviation δ. Then, a signal for correcting the digging direction of the excavator 1 is output in accordance with the calculated value δ.

FIG. 4 is a plan view when the position detection device of the above embodiment is applied to excavation when the excavation target line is a curved line. The configuration and operation of the devices shown in a to c are the same.

As described above, in this embodiment, guide wires are laid at equal intervals on both sides of the excavation target line, and the interval between the guide wires is made to be approximately equal to the distance between the guide wire and the magnetic field detection device. , an alternating current is supplied to this guide wire, the magnetic field generated in the guide wire is detected by two magnetic field detectors installed in the excavator, and the position deviation is calculated based on the detected magnetic field strength. Since the excavation direction of the excavator is controlled according to the position deviation, there is no need to equip a surveying instrument or an automatic tracking device, and the position of the excavator can be quickly, easily, and automatically determined with high sensitivity. It is also possible to completely automate the control of the excavation direction of the excavator. Furthermore, even if the excavation target line is a free curve, position detection and excavation direction control can be carried out in the same way as when the excavation target line is a straight line.

In addition, in the description of the above embodiment, an example in which the guide wire is laid on the ground surface has been described, but the guide wire may be buried in the ground. Also, the number of installed magnetic field detectors,
The installation location and magnetic field detection direction are not limited to the above example, and can be selected as appropriate. Furthermore, various types of magnetic field detectors can be used in addition to coils.

〔Effect of the invention〕

As described above, in the present invention, the excavator is provided with a magnetic field detection device, and guide lines are laid on both sides of the excavation target line at an equal distance from the excavation target line, and the distance between the guide lines is is selected to approximately match the vertical distance between the installation surface of the guide wire and the magnetic field detection device, and the magnetic field generated by supplying current to the guide wire is detected by the magnetic field detection device. Therefore, there is no need to provide a surveying instrument or an automatic tracking device, and the position of the excavator can be quickly, easily, and automatically detected with high sensitivity and accuracy. It can also be applied to curved excavation.

[Brief explanation of the drawing]

Figures 1a, b, and c are a plan view and a sectional view of a position detection device according to an embodiment of the present invention, and Figures 2a and b are sectional views showing the position of the excavator and characteristic diagrams of magnetic field strength for this position. , Fig. 3 is a characteristic diagram of detection sensitivity with respect to the distance between guide wires, Fig. 4 is a characteristic diagram of Fig. 1a,
FIGS. 5 and 6 are plan views in which the position detection device shown in b and c is applied when the excavation target line is a curved line, and sectional views of the conventional position detection device. 1... Excavation machine, 11a, 11b... Magnetic field detector, 12... Guide wire, 13... Power supply, 14... Controller, T... Excavation target line.

Claims (1)

[Claims] 1. In an excavator that excavates underground, continuous guide wires are placed on both sides of the excavation target line of the excavator at equal intervals from the excavation target line, and a current is supplied to the guide wires. The tunneling machine is equipped with a power source that generates a magnetic field, and a magnetic field detection device arranged at a target position with respect to the vertical plane of the tunneling machine, and the distance between the guiding wires is determined based on the installation surface of the guiding wire and the magnetic field. A position detection device for an excavator, characterized in that the device is selected so as to approximately match the vertical distance between the detection device and the detection device.