JPS6022311B2 - Cable search method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cable search method for detecting the position of installed cables, particularly cables installed underground, under the sea, or at the bottom of a river.

In recent years, in order to prevent cables from being broken by fishing nets, ship anchors, etc., it has become popular to bury cables under the ocean floor or riverbed.

When attempting to dig up such a buried cable for repair or pull it onto a repair ship, conventionally, a special hook shaped to comb deeply into the soil of the ocean floor is towed in a direction across the cable. However, the method used is to hook the cable onto the ship and pull it up onto the ship. However, since the cable is buried in the sand, if the towing of the hook is not stopped immediately when the cable is caught on the hook, the cable will be severed by the hook.
Therefore, the hook had to be towed at extremely low speeds, which meant that pulling up the cable was a long process. As a way to solve this drawback,
For example, by detecting the magnetic field generated by the current applied to the cable from the terminal station using multiple magnetic field detectors and calculating the detection signal output, a cable detection machine can obtain information about the cable installation position. There is also a method for guiding and controlling buried machinery to a predetermined position promptly (Tsubaki Gansho No. 54-96656).

However, this method requires relatively expensive equipment such as a computer and advanced arithmetic processing. It is an object of the present invention to solve the above-mentioned drawbacks of the conventional techniques and to provide a cable search method using a simple device.

To achieve this objective, the present invention provides a cable detection means that detects the magnetic field from the cable by radially arranging a plurality of magnetic field detectors so that each has substantially the same sensitivity in the same direction. , a line having a length proportional to the output of the magnetic field detector in a direction from the reference point to the arrangement position of the magnetic field detector on the display surface, with the center point of the magnetic field detection means corresponding to a reference point on the display surface; The present invention is characterized by comprising a display means that allows the direction of existence of the cable to be determined based on the relative position of a display figure formed by connecting the ends of each line segment with respect to the reference point.

According to the present invention, since it is possible to detect whether or not a cable is defective even from a distance, it is possible to greatly improve the efficiency of cable searching work.

Further, when burying a cable, the direction of the cable with respect to the burying machine can be detected, so that the cable burying machine can be easily guided and controlled. The present invention will be explained in detail below with reference to the drawings.

FIG. 1 shows an embodiment of the cable detection system of the present invention.

If a fault occurs in the cable 14 laid on the seabed and the conductor is grounded at the fault point 8, the search AC signal source 12 can supply the search AC current to the cable, and the search AC signal source 12 can supply the search AC current to the cable. The return path of the current is formed by the ground fault point 18 and the ground point 16 of the search AC current source 12.The AC magnetic field generated by this search AC current is detected by the magnetic field detector group 2 composed of N magnetic field detectors. The magnetic field detector group 2 also detects the magnetic field caused by the earth's magnetism.
While the magnetic field caused by earth's magnetism is a direct current magnetic field, the magnetic field caused by the search alternating current is an alternating current magnetic field, so the search alternating current magnetic field can be easily extracted by the filter circuit. The electrical signal output of the magnetic field detector group 2 is sent to the receiving section 4 on the mother ship through a signal line. Figure 2 shows magnetic field detector group 2.
This is one configuration example of the receiving section 4.

The magnetic field detector group 2 is composed of four magnetic field detectors 21, 22, 23, and 24 having the same sensitivity and arranged in a square shape. 2
The outputs of the magnetic field detectors 20 and 22 are
Connect to two resistors with the same resistance value, and ground the resistor with the same resistance value connected in series.

The terminals of each resistor are the contacts 24, 25 of the 7-contact switch 6,
26, 27, 28, 29, 30' are connected. Two other magnetic field detectors 2 located symmetrically about the center of the square
Each terminal of the resistor connected to the outputs of 1 and 23 is connected to each terminal of the other 7 contact switch 8, 32, 33, 34, 35, 36, 37.
, 38, and the middle terminal of each 7-contact switch is grounded. Contacts 31 and 3 of 7-contact switches 6 and 8
Reference numeral 9 connects the X-axis and Y-axis inputs of the X-Y scope 10 to the respective terminals 24 to 30 and 32 to 38 of the seven contact switches 6 and 8 in order.

In the case of Fig. 2, the contact 31 is connected to the terminal 27 and the contact 31 is connected to the terminal 27.
9 is connected to the terminal 32. At this time ×-Y scope 1
0 indicates a marking point. The contacts 31 are, for example, terminals 27 → 28 → 29 → 30 → 29 → 28 → 27 → 26 → 2
5→24→25→・・・・・・・・・・・・・・・Contact 39 connects terminals 32→33→34→35→36→3T→ in synchronization with the switching of contact 31 38
→ 37 → 36 → 35 → 34 and so on.
At that time, X-Y scope 10' points 40 → 41 → 42
→43→44→45→46→47→48→49, and the combination of these points displays a quadrilateral. In this case, the number of resistors connected in series can be any number instead of three.In that case, the number of contacts also changes.Also, instead of a fixed resistor, you can use a three-terminal variable resistor whose contacts change continuously. As the multi-contact switches 6 and 8, it is possible to use a combination of two rotary switches and a pulse motor, or a relay or analog switch controlled by a logic circuit. The figure shows the relative positional relationship between the cable and a magnetic field detector group 2 made up of magnetic field detectors having uniform detection sensitivity directivity, and the relationship between the shape of the figure displayed on the receiver 4.

Figure a shows a case where the cable hook 4 is laid in a direction substantially perpendicular to the straight line connecting the magnetic field detectors 2Q and 22. The output amplitude of the magnetic field detector is approximately inversely proportional to the distance between the magnetic field detector and the cable. Therefore, the displayed figure is convex in the direction of the marking point 43 corresponding to the magnetic field detector 201 located closest to the cable 14 among the four magnetic field detectors 20, 21, 22, and 23. Figure b shows a case where the cable installation direction is almost parallel to the straight line connecting the magnetic field detectors 20 and 21.
The displayed figure is approximately trapezoidal, and is biased towards the marking points 40, 43 corresponding to the magnetic field detectors 20, 21 near the cable 14. Figure c is a 900-degree turn of figure a, in which the cable 14 is laid in a direction almost perpendicular to the straight line connecting the magnetic field detectors 21 and 23, and the displayed figure shows four magnetic field detectors 20, It is convex in the direction of the marking point 40 corresponding to the magnetic field detector 21 located closest to the cable 14 among 21, 22, and 23. Figure d is in the same state as figure c, but the distance between the cable 14 and the magnetic field detector group 2 is larger than that in figure c. In this case, since the output of each magnetic field detector becomes small, the displayed figure also becomes small compared to that shown in FIG. As can be seen from the above four figures, the general direction and distance of the cable installation position can be easily determined from the shape of the displayed figure. In this case, the laid cable connects four magnetic field detectors 20, 21
, 22, and 23 do not have to be included in the plane formed by them. In the embodiment shown in Figure 2, part of the cable is 4
However, in such a case, the embodiment shown in FIG. 4 is suitable.

The magnetic field detector group 2 includes two magnetic field detectors 20 having the same sensitivity.
and 22. The output of each magnetic field detector 20, 22 is connected to three series-connected resistors having the same resistance value, and the terminals of the series-connected resistors are grounded. The terminals of each resistor are the contacts 24, 25, 26 of the 7-contact switch 6.
, 27, 28, 29, 3 rivers are connected. Contact 31 is X-
The input of one axis of the Y scope 10 and each terminal 24 to 30 of the seven contact switch 6 are connected in order. In the case of FIG. 4, the contact 31 connects to the terminal 3, and then displays the X-Y scobo terminal 52. Contact 3i is sequentially connected to terminal 30 → 29 →
28→27→26→25→24→25→26→…………
...Connect like this ~ At that time, the x-Y scope sequentially points 52 → 53 → 54 → 55 → 56 → 57 → 58 → 57 → 5
6 →.・…． It is displayed like this. The combination of these points represents a line segment. FIG. 5 shows the relative positional relationship between the cable and the magnetic field detector group and the relationship between the shape of the figure displayed on the receiving section.

Figures a to c show the case where the cable 14 is substantially orthogonal to the straight line formed by the magnetic field detectors 20 and 22. Figure a shows a case where the cable 14 is two magnetic field detectors close to each other, and the displayed figure is such that the direction of the marking point 52 corresponding to the two magnetic field detectors is longer than the direction of the marking point 58. Figure b shows the case where the cable 14 is located at a position that roughly bisects the line segment connecting the magnetic field detectors 20 and 22, and the shape of the displayed figure is symmetrical about the marking point 55 corresponding to the ground potential. Become something. Figure c shows a case where the cable 14 is located outside the magnetic field detector 20, and the shape of the displayed figure extends in the direction of the marking point 52 corresponding to the two magnetic field detectors. As can be seen from the above three figures, information about the cable laying position and the distance between the cable and the magnetic field detector can be known from the shape of the displayed figure. It is also clear that the cable 14 does not have to be included in the plane containing the two magnetic field detectors. Note that in this embodiment, the cable 14
It is assumed that is substantially orthogonal to the straight line connecting the two magnetic field detectors 20 and 22. FIG. 6 shows another embodiment of the display 4 in which a square magnetic field detector group 2 is used.

The outputs of the pair of magnetic field detectors 20 and 22 are connected to input terminals 59 and 6 of a changeover switch 62 controlled by a control circuit 71.
Connect to 0. The output of the changeover switch 62 passes through a sign control circuit 67 and is integrated by an integrator 69. The sign control circuit 67 controls the sign of the signal based on the output of the control circuit 71. Integrator 69 can be reset by the output of control circuit 71. The output of the integrator 69 is input to the Y axis of the x-Y scope. Similarly, a pair of magnetic field detectors 21,
The output of 23 is a changeover switch 66, a code controller 68,
It passes through an integrator 70 and is input to the x-axis of the X-Y scope 10. The outline of the operation is as follows. Magnetic field detector 20,2
The outputs of 1, 22, and 23 are respectively Vm2o, Vm21,
Let Vm22 and Vm be negative, and let the outputs of integrators 69 and 70 be IY and lx, respectively. First, reset the integrator output and set it to x: -Vm217, IY=0 (7 is a constant)
. At this time, the X-Y scope 10 displays a point 72. Set the changeover switch 62 to the 59 side, and turn the changeover switch 6
6 is turned to the 64 side, and the sign controllers 67 and 68 set the sign not to be inverted. If the integrators 69 and 70 are used to integrate only the time value, lx=0, IY=Vmsha7, and the marking point moves linearly from 72 to 73. Next, the changeover switch 66 is set to the 63 side, the sign inverter 67 is set to the sign inverting state, and a time period 7 is integrated. Then lx=Vm
237, IY=0, and the marking point moves linearly from 73 to 74. In this way, by appropriately controlling the changeover switch and sign inverter, the number of marking points can be increased to 74.
→75→72, and its locus is square 72, 73,
74, 75. The zero point drift of the integrators 69 and 70 can be removed, for example, by resetting the integrators at the moment when the marking point returns to 72 after completing one cycle, and setting lx=-V ↑ and IY=0. In the case of N=2 and N=4, the circuit configuration can be simplified as explained above. An example for a general case of N will be described below. FIG. 7a shows one example, and it is assumed that the output of each magnetic field detector is converted into a positive DC voltage. cos calculator 80
and sine calculator 81 for each magnetic field detector i (i=1, 2
,......N) output V; is expressed as Vicoso' (or V
islnoi). In Fig. 7b, cos calculator 8
0 (or sine operator 81) is shown. Input V
, is divided by two resistors R,,R2, and the ratio is equal to the absolute value of coso, (or sin8,). That is, R, so that R, ear ± wide = lcosail or lsino, l. , R2.

By controlling the sign of the divided voltage V2 by the sign controller 82 according to the sign of cosai (or sinai), V3 expressed by the following equation is obtained.

V3=V, cosoi or V, output of sinoicos operator 80 and sine operator 81 V, cosoi, v
isln8, (i=1, 2,...
・N) are connected to the X-axis and Y-axis of the X-Y scope 10 in order by the changeover switches 6 and 8.

That is, the input voltages of the X-axis and Y-axis of the X-Y scope are V, respectively.

cos80 → V, cos8, → V length os02 →...
・・・・・・・・・・・・→ViC0S8i→.・・・．・・・
．．・・・． ...V. sin80→V, Sin8, →V cross in82 →““””””…→VISmai→“”“”
Changes to “”…. Therefore, the distance from the center of the marking point and the phase are respectively QV.

→QV, →QV2→””“”””…→QVi→”””“
””…→QVN→QV,→“”””””…(Q is a constant)
0.

→0, →82 →””””””…→8i→””””・8
It changes as follows: N→8,→”””””””.

These marking points indicate each point of the N-gon. FIGS. 8 and 9 show examples of how the cable detection method of the present invention is used.

Figure 8 shows a cable detector mounted on a vehicle that can move freely on the seabed to detect cables, and Figure 9 shows a cable burying machine for guiding a cable burying machine along a cable when burying a cable. An example of each application is shown when performing cable detection.

In FIG. 8, 76 is a cable ship, 77 is a vehicle having a signal line inside, 83 is a self-propelled vehicle, 84 is a vehicle control device, 14 is a cable, 80 is a sea level, 8
1 is the seabed surface. The cable detector 82, which is composed of four magnetic field detectors, detects the magnetic field (dotted line in the figure) generated by the search alternating current supplied from the Luyang station to the cable 14.
is detected, and the detection signal is transmitted to the receiving section in the cable ship 76 through the signal line in the driver 77.

On the cable ship, it is possible to know whether the cable is faulty or not based on the displayed graphic and guide the peakle onto the cable 14. FIG. 9 shows an embodiment in which the present invention is applied to cable tracking when burying a cable, and FIG. 9A is a plan view and FIG. 9B is a front view.

Components common to those in FIG. 8 are given the same numbers. 86
is a cable burying machine.

In the figure, in order to bury the cable 14 with a cable burying machine 86, it is necessary to detect the position of the cable 14 and to control the cable burying machine to accurately direct the cable 14 onto the cable 14. Therefore, the cable detector 82 is connected to the buried machine 86.
It will be mounted on the front of the In this embodiment, the cable 14 and the burying machine 86 are kept almost parallel, so
The cable detector 2 composed of the two magnetic field detectors 20 and 22 shown in FIGS. 4 and 5 can be applied. In this example, the position of the cable is detected using the same principle as explained using FIG. 8, and based on the result, the steering mechanism of the cable tracking control device is controlled in order to guide the cable burying machine 86. It is something. It is also possible to use a metal detector instead of a magnetic field detector.

In addition, although the above description is about the case where the cable is on the seabed, the application is not limited to the seabed, but can also be applied to detecting the position of cables buried on land, cables laid in rivers, indoor catenary lines, etc. Needless to say.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a configuration example of a cable search method according to the present invention, FIG. 2 is a circuit diagram showing a configuration example of a magnetic field detector group and a receiving section used in the present invention, and FIGS. 3a, b, and c are A diagram illustrating an example of a display graphic according to the present invention, FIG. 4 is a circuit diagram showing another example of the configuration of a magnetic field detector group and a receiving section used in the present invention,
Figures 5a, b, and c are diagrams showing examples of display figures according to the configuration example of Figure 4, and Figures 6 and 7a, b are other configurations of the magnetic field detector group and receiving section used in the present invention. A block diagram showing an example, a partial circuit example diagram thereof, and FIGS. 8 and 9 are drawings showing an example of use of the cable search method of the present invention. 2... Magnetic field detector group, 4... Receiving section,
6, 8...Switch, 10...X-Y scope, 1
2... Search alternating current source, 14... Cable,
6...Ground point, 18...Ground fault point, 2
0, 21, 22, 23... Magnetic field detector, 24,
25, 26, 27, 28, 29, 30, 32, 33, 3
4, 35, 36, 37, 38... Cutting contact, 3
1,39...・・・． Contact, 40, 41, 42, 43,
44, 45, 46, 47, 48, 49, 50, 51...
...・Marking points, 59, 60, 61, 63, 64, 65...
Terminals, 62, 66... Selector switch, 67, 68...
...Sign controller, 69,70...Integrator, 7
1... Control circuit, 72, 73, 74, 75...
...marking point, 76 ... cable ship, 7
7...Hinso, 80...Sea level, 81.
... seabed surface, 82 ... cable detector,
83...Vehicle, 84...Cable control equipment, 86...Cable burial machine, 90.
...COS computing unit, 91...sin computing unit, 92...sign controller. , key figure destination 2 figure ice 3 figure age 4 figure ne 5 figure ice 6 figure outside 7 figure O 8 figure outside 9 figure

Claims (1)

[Claims] 1 In a cable search method in which alternating current is supplied in advance to the cable to be searched, an alternating magnetic field is generated from the cable, and the alternating magnetic field is detected to determine the direction of the cable as seen from the detection point. magnetic field detection means for detecting the magnetic field from the cable by arranging detectors radially so that they have almost the same sensitivity when viewed from a central point;
A line segment having a length proportional to the output of the magnetic field detector from the reference point on the display surface in the direction of the arrangement position of the magnetic field detector, with the center point of the magnetic field detection means corresponding to a reference point on the display surface. A cable search method characterized by comprising: a display means that displays a display figure formed by connecting the tips of each line segment, and allows the direction of existence of the cable to be determined based on the relative position with respect to the reference point of a display figure formed by connecting the ends of each line segment.