JPH0415501A - Method and device for measuring embedded position of metallic long-size object - 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] [Industrial Application Field] The present invention provides electromagnetic transport for long metal objects buried underground, such as electric cables, metal pipes housing them, gas pipes, water pipes, etc. The present invention relates to a method and apparatus for measuring the buried position and depth using an induction method.

[Prior Art] A conventional method for searching from the ground for long metal objects buried underground, such as electric cables, metal pipes housing them, gas pipes, water pipes, etc., is to detect long metal objects using a transmitting coil. While generating an induced current, move the receiving coil horizontally to find the position where the output voltage obtained by the magnetic field caused by the induced current shows the maximum value, and confirm that a long metal object is buried directly below the position. The depth was measured by detecting the depth, then changing the height of the receiving coil at that position and calculating the output voltages at the top and bottom of the receiving coil.

That is, as shown in FIGS. 6(a) and 6(b), a pulse current or alternating current of a certain frequency is applied to the transmitter coil 6I from the transmitter 62 on the ground where the long metal object 1 is believed to be buried. When a current is applied, an induced current I flows through the long metal object l due to the magnetic field He created thereby. Cylindrical magnetic field HB3 created by this induced current ■
If a receiving coil 63 is placed inside, a current flows through the coil 63, and a voltage across the coil 63 is measured by a voltmeter 64.

At this time, the coil axis of the receiving coil 63 is horizontally moved on the ground, and its direction is also changed at the same time.
If we find the position and direction where the output voltage is maximum, it means that the long object 1 is buried directly under that position, and that the long object 1 runs in the direction perpendicular to the coil axis. Become.

That is, as shown in FIG. 6 (b), at a certain position L+, place the receiving coil 63 with its coil axis horizontally, change the direction, and find the direction that gives the maximum value of the output voltage displayed on the voltmeter 64. . This direction is perpendicular to the long metal object I. At this position, the strength of the magnetic field is Hl, its horizontal component is HX, the length of the straight line connecting the long metal object I and the receiving coil 63 is R1, its vertical component is D, its horizontal component is, If we represent the horizontal component of the above magnetic field as Hx and the angle between it and the straight line direction of the above length R as 0, then the strength of the horizontal component of the magnetic field is Hx=Hsinθ, H=/R, D/ Since R=sinθ, HX=KD/(L
'+D') However, K is a constant determined in proportion to the magnitude of the induced current, and the distance L=O of the horizontal component is the strength of the magnetic field Hx
This is the position where the receiving coil 63 is moved horizontally to maximize its output voltage. It can be seen that there is a long metal object I directly below.

[Problems to be Solved by the Invention] As described above, in the conventional measurement method, the receiving coil 63 is moved horizontally to a position where the current induced therein is maximum. In other words, the position where the output voltage of the voltmeter 64 is maximum is determined. However, since the measuring person holds the receiving device with the receiving coil 63 in his hand and moves it horizontally, the height of the receiving coil 63 is determined. Due to slight differences in the coil axis, the horizontality of the coil axis, the direction perpendicular to a long object, etc., the measured value of the output voltage tends to vary from person to person. It was difficult to determine the exact burial location and depth due to the wide range that was difficult to identify.

[Means for Solving the Problems] The buried position measuring method and device of the present invention reduce the individual differences in the measured values by the above-mentioned measurers, and are capable of accurately determining the buried position and depth. The measurement method is to measure the direction of the coil axis of either the transmitting coil or the receiving coil at two different positions at approximately the same height above the ground surface. Rotate in a plane orthogonal to The buried position of the long object is determined from the distance and each of the above-mentioned rotation angles.

Further, in the buried position measuring device of the present invention, two transmitting coils are provided on each of two parallel rotating axes spaced apart in a horizontal plane, the coil axes of which are in the same plane and perpendicular to the rotating axes. , a transmitter connected to these transmitting coils via a changeover switch, a rotation angle detector of the rotating shaft driven through a changeover switch linked to the changeover switch, a metal length buried by the rotation angle and the transmitting coil. a transmitter comprising a receiver and an arithmetic processor that calculates the position of the long object by inputting an induced current generated in the long object; a receiving coil that detects the induced current; and a transmitting device that detects the induced current. a transmitter for transmitting data to a receiver; and a receiving device.

[Function] According to the method for measuring the buried position of a long metal object of the present invention, an induced current is generated in the long metal object when the magnetic field created by the coil current of the transmitting coil crosses the long metal object.
The direction of the coil axis of either the transmitting coil or the receiving coil of the receiving device was rotated so that the current was measured to be zero, and the rotation angle from the horizontal position was determined at two different positions. Therefore, as will be described later, since the range of rotation angles in which the induced current is measured to be zero is very narrow, the buried position of the long metal object can be determined very accurately.

Further, according to another buried position measuring device of the present invention, two transmitting coils are provided perpendicularly to the rotation axis with an interval between two locations where the angle of rotation is to be measured, and the rotation of these coils determines the distance between the two locations where the rotation angle is to be measured. The rotation angles of the two legs at two points when the induced current becomes zero are input to the processor, and the predetermined intervals between the two points are also manually set in the processor. , the position at the burial depth can be displayed on the display at the same time as the position at the ground surface.

[Embodiment] First, an embodiment of the buried position measuring device for a long metal object of the present invention will be described with reference to FIG.

11 is a transmitting device, 12 is a receiving device paired with this, and the transmitting device II has two transmitting coils I3A, I
3a, which are mounted perpendicularly in the same plane to rotating shafts 14A and 14B which are provided parallel to each other at intervals in a horizontal plane, and are connected to the motor I, respectively.
5A, rotated by I 5e. I 6A, I
Reference numeral 6a denotes a rotation angle detector provided on each of the rotating shafts 14AS14B, which allows the transmitting coils 13A,
The rotation angle of each coil shaft 13e from the horizontal position is detected. 17 is a transmitter, changeover switch SWI
It is switched and connected to either the above-mentioned transmitting coil +3A or 13s. Also 18 is a bipedal motor 15
The power supply is connected to A and 15B through the changeover switch SW2, and the changeover switches SWI and SW2 are interlocked, and when the transmitter I7 is connected to the transmitting coil 13A side, the power supply 18 is connected to the motor 15A side by the changeover switch SW2. It should be connected to. I9 is a wireless receiver that receives a signal regarding the magnitude of the induced current value of the buried long metal object l from the wireless transmitter of the receiver 12, and 20 receives information regarding the induced current value received by the receiver I9 and the rotation. An arithmetic processor that calculates the buried position and depth of a long metal object by performing arithmetic processing from the information regarding the respective rotation angles from the angle detectors 16A and 1613; 2I is the result of the arithmetic processing and the induced current value; This is a display that displays two rotation angles, etc.

Further, the receiving device 12 includes a receiving coil 22, a detection amplifier 23, and a wireless transmitter 24, and includes a buried metal long object I
A pulse signal regarding the induced current value is transmitted wirelessly and is received by a wireless receiver 19 of the transmitting device 11.

Next, the measurement operation will be explained with reference to the same figure.

First, the transmitting device 11 and the receiving device 12 are brought to a place where the long metal object 1 is believed to be buried, and a pulse current is passed from the transmitter I7 to the transmitting coil 13A through the switch SWl. The magnetic field created thereby generates an induced current I in the long metal object 1 buried underground. When the induced current I crosses the receiving coil 22 of the receiving device 12 with the cylindrical magnetic field created thereby, a pulse current is induced there, and the detection amplifier 23
The signal is amplified by the radio transmitter 24 and received by the radio receiver 19 of the transmitter 11 as a pulse wave.

Then, the pulse current, the output voltage of the receiving coil 22, or the induced current at that time is displayed on the display 21 through the arithmetic processor 20.

In the above, when the transmitting device 11 is moved horizontally and its direction is changed, as the transmitting coil I3A approaches directly above the long metal object 1, and as the coil axis approaches the direction perpendicular to the long object 1, Therefore, the induced current I increases, and similarly, as the receiving device 12 approaches directly above,
Furthermore, it will be easily understood that as the direction of the receiving coil 22 approaches the direction perpendicular to the elongated object 1, the measured value of the induced current I increases.

Next, the motor I5A is rotated through the transmitting coil +3A from the power source I8 to SW2, and when the coil axis of the transmitting coil +3A is directed toward the long metal object 1, the induced current I generated there becomes zero (0). It should be. therefore,
It can be seen that the long metal object 1 will exist in the direction of the coil axis when the induced current 2 becomes zero (0).

Similarly, the switch SWI of the transmitter I7 is switched to the transmitting coil +3e side, thereby
W2 switches to the motor 15a side, and the transmitting coil 13a
It is known that the long metal object I will exist in the direction of the coil axis when the induced current I is displayed as zero (0).

In this way, the length between the transmitting coils 13A and 138 and the angles at both ends thereof are determined, and one side of the triangle and the two sides at both ends thereof are determined.
Since the angle is determined, the buried position and depth of the long metal object I can be determined.

In order to facilitate understanding of the bipedal measurement method, its basic principle will be explained with reference to FIGS. 2 to 4.

First, in Fig. 2, ■ is a long metal object buried underground, 2 is the ground surface, I7 is a transmitter, and I3 is a transmitting coil, whose coil axis is in a plane perpendicular to the long metal object 1. , R is the length of the straight line connecting the transmitting coil 13 and the long metal object I, D is the length of the vertical component, L is the length of the horizontal component, and θ is Let it be the angle between a straight line of length R and a straight line of length.

Assuming that the coil axis of the transmitting coil 13 is placed horizontally, the current I induced in the long metal object l at that time is I=Ksinθ/RK is a constant R=L 2+ D', sinθ-D/ Since it is R, when D20, the induced current becomes I-0, and when L-0, the induced current l becomes the maximum value.

Next, as shown in Figure 3 (A) with the same configuration as Figure 2,
Considering the case where the direction of the coil axis of the transmitting coil 13 is rotated by an angle θ1 from the horizontal position in a plane perpendicular to the long metal object I in which it is included, that is, in a plane perpendicular to the ground surface 2. 1-Ksin(θ-θ,)/R, where the induced current I is a function of θ, and when θ, -0, the induced current ■ becomes zero (0).

The situation is shown in Figure 3 (b). In FIG. 3, the vertical axis represents the induced current (2), and the horizontal axis represents the rotation angle at which the coil shaft is rotated from the horizontal position. As can be seen from this figure, the induced current I shows a very steep change near zero (0), so the orientation of the transmitting coil 13 at θ, = θ accurately indicates the position of the buried metal elongated body I. It will be seen that even if , θ, is slightly away from θ, the induced current l will flow, and it will change greatly. On the other hand, at θ, -90°+θ, the induced current I reaches its maximum value, but the value does not change much even in the vicinity.
Therefore, the position showing the maximum value is likely to have a considerable error.

Next, as shown in FIG. 4(a), the transmitting coil I
3 in a plane perpendicular to the long metal object 1 that contains it, at two different positions on the ground surface at the same height, so that the induced current ■ becomes zero (0) at L2. Rotate. When the rotation angle of the coil shaft from the horizontal position at position 1 is OA, and the rotation angle from the horizontal position at position 2 is θB, the induced current I flowing through the long metal object 1 due to these changes is The changes are shown in Figures 4 (b) and (c). In the figure, the vertical axis is the induced current I, and the horizontal axis is the rotation angle OA.
and θB.

Now, the distance between each position and 2 is LA e, and the distance of the horizontal component from those positions to the long metal object 1 is I,
AXLB, if the distance of the vertical component is D, then LA B = LA +, LB = LD =
From the above two equations L A tanθA = L B tanOB, D = L tanθA tanOB / (tar+
f9 A + tanOB) LA=Ltanθs/(t
anoA+LanθB) or L B −L tanθA /(tanθA + tan
As θr3), the position and depth of the buried long metal object can be determined.

'' In the two-legged explanation, the coil axis of the transmitting coil 13 is placed in the same plane at two locations, and the direction of the coil axis is rotated in a plane perpendicular to the long metal object 1. As explained above, as shown in Figures 5 (a) and (b), although it is at the same height and in a plane orthogonal to the ground surface 2, it is not orthogonal to the long metal object I. Even if the direction of the coil axis of the transmitting coil (3) is rotated at two positions within the plane, the buried position and depth can be determined in exactly the same way. In this case, if the angle between the plane containing the coil axes at two locations and the long metal object I becomes smaller than a right angle, the induced current ■ will only become smaller accordingly, so it will not become significantly smaller than the above-mentioned right angle. In other words, as long as the induced current (2) does not become too small, the buried position can be determined accurately.

According to the further basic principles of this measurement method, the heights of the two transmitting coils may be at different heights above the ground surface, and the planes including the coil axes at the two locations and around which they rotate are relative to the ground surface. It is easy to see that it may be slanted, although this is not very practical.

In addition, in the above embodiment, the transmitting coils 13A, 1
Although we have explained the case where the direction of the coil axis of 3e is rotated to change the current induced in the long metal object, as another example, it is possible to generate an induced current in the long metal object with one transmitting coil. Then, on the receiving device side, rotate the coil axes of the two receiving coils at different positions so that the induced current actually flows, but from the horizontal position where the measured value is zero (0). It is easily understood that the position where the long metal object is buried in the receiver can be determined from the rotation angle and the distance between the two receiving coils.

[Effect of the invention] - According to the method for measuring the buried position of a long metal object according to the invention in 1, transmission or reception when the measured value of the induced current generated in the long metal object becomes zero (0). Since the rotation angle of the coil axis direction is measured, the induced current changes greatly with small changes in the rotation angle, and the rotation angle can be determined very accurately. , a coil in which the measured value of the induced current is zero (0) even if the plane containing the rotational surface of the coil axis is not exactly orthogonal to the long metal object at the two positions measured by the transmitting or receiving coil. The rotation angle of the shaft can be read very accurately, and therefore the buried position and depth of the long metal object can be determined very accurately.

According to another measuring device of the present invention, two transmitting coils are provided at regular intervals, each rotated in a plane orthogonal to the ground surface, and each transmitting coil is rotated at a set value of the regular interval. Since the rotation angle is input to the arithmetic processor, if you bring the device to the measurement site and perform the measurement operation, you can accurately determine the buried position and depth of the long metal object in the same way as described in the measurement method above. can be found.

[Brief explanation of drawings]

FIG. 1 is a perspective view including a block diagram showing the structure of the device for measuring the buried position of a long metal object according to the present invention, and FIGS. Figure 2 shows the front view of the transmitter coil, Figure 3 (a) shows the front view, and figure (b) shows the induced current and the rotation angle of the transmitter coil. Figure 4 (a) is a front view; Figures (b) and (c) are curve diagrams showing the relationship between induced current and the rotation angle of the transmitting coil; Figure 5 (a) and (b) a front view and a plan view showing another operating state, and FIG. 6 is a simplified perspective view of a measuring device for explaining a conventional measuring method. I; long metal object, 2. earth surface, 11; transmitter, 12;
Receiving device, 13.13A, 13B: Transmission coil, 14A
, 14B; Rotating shaft, 15A1158: Motor, 16A,
16th: Rotation angle detector, 17; Transmitter, I8. power supply, 1
9: Wireless receiver, 20 arithmetic processor, 21: Display device, 22
: Receiving coil, 23; Detection amplifier, 24: Radio transmitter.

Claims (2)

[Claims] (1) In a method of measuring the buried position of the long metal object by generating an induced current in the buried long metal object by the coil current of the transmitting coil and measuring the current with a receiving device, the transmitting coil or The direction of the coil axis of either one of the receiving coils of the receiving device is rotated in a plane that includes that axis and is perpendicular to the ground surface, and the induction of the buried metal long object caused by the coil current of the transmitting coil is Find the rotation angle of the coil shaft from the horizontal position when the current is measured to be zero, and then calculate the rotation angle of the coil shaft at a position different from the above position but at approximately the same height from the ground surface. Rotate the direction of the coil axis within the same plane as above, find the rotation angle of the coil axis from the horizontal position in the same way as above, and calculate the distance between the two measurement positions of the coil and each of the rotation angles above. A method for measuring a buried position of a long metal object, characterized in that the buried position of the long metal object is determined from . (2) Two transmitting coils whose coil axes lie in the same plane and are orthogonal to the rotary shafts are installed on each of two driving rotary axes that are spaced apart and parallel to each other in a horizontal plane. a transmitter connected via a changeover switch; a rotation angle detector of the rotating shaft driven through a changeover switch linked to the changeover switch; a transmitting device consisting of a processor that inputs the induced current etc. that occurs and calculates the position of the long object, and a receiver; a receiving coil that detects the induced current; and a receiving coil that transmits the induced current to the receiver of the transmitting device. 1. A buried position measuring device for a long metal object, comprising a receiving device consisting of a transmitter for transmitting data.