JP2007255986A - Position measuring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position measuring system capable of acquiring accurately a lateral moving amount and a moving direction in the sea or under the ground in a reclamation work field or in a wide landslide area. <P>SOLUTION: A transmitter 10 having a uniaxial coil 12 for generating an alternating field is buried under the ground or under the sea-bottom ground. In order to receive the alternating field, a detection coil system including the first and second coils CA, CC installed at an interval on the first axis S1 arranged on the ground surface or near the sea surface and the third and fourth coils CB, CD installed at an interval on the second axis S2 orthogonal to the first axis S1 is prepared. A signal processing circuit system includes band-pass filters 16A-16D, differential circuits 17-1, 17-2, and phase detection circuits 18-1, 18-2, processes each detection signal from the first to fourth coils, and determines two-dimensionally a relative position between the axial position of the uniaxial coil and the detection coil system center from a differential signal between each detection signal from the first and second coils and a differential signal between each detection signal from the third and fourth coils. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a position measurement method, and in particular, measures the amount of movement and the direction of movement when the seabed ground moves sideways due to the load of the reclaimed earth and sand, and when the soil mass above the slip surface moves in the landslide area. The present invention relates to a position measurement method suitable for.

  In the construction of offshore airports, ground facilities are constructed by reclaiming a large amount of earth and sand on the seabed and forming land. Until now, the subsidence of the submarine ground itself has been regarded as a problem, and a method of measuring the subsidence of the submarine ground from changes in water pressure has been used mainly by using pressure sensors and telemeters.

  The reason for this is that the amount of earth and sand in landfilling accounts for the majority of the construction cost, so regular management of the amount of subsidence in the seabed was regarded as important in order to reduce the construction cost.

  On the other hand, in landfill work in areas where the subsidence of the seabed is low (the seabed), the lateral flow of the seabed (such as sludge) caused by the load of the landfill is regarded as important. There is a need to manage.

  Also, in the landslide area, when measuring the amount and direction of movement of the mass at the time of landslide occurrence, in conventional areas such as landslides and strain gauges in areas where there are obvious changes in the ground surface such as cracks, Observing with the measuring instrument of was carried out. On the other hand, when a large-scale soil mass moves, it is difficult to measure the change in the relative amount of movement between the upper soil mass near the slip surface and the lower ground and the direction of the movement, and the slip surface across the slip surface is difficult. An accurate measurement has not been performed so far, in which a method (for example, see Patent Document 1) in which a wire is fixed on the lower side and a wire pull-in amount on the ground surface is used to obtain a relative movement amount is used. In addition, in such areas, there are many vegetation, and the use of optical surveying and GPS is also limited.

JP-A-8-21750 JP 09-53958 A JP 2004-234335 A

  In land reclamation works in harbors and in the observation of the direction of movement of the ground (sea floor) and soil blocks in a wide range of landslide areas, in the case of the sea, measurements are made in seawater, so disturbances such as falling sediments, tide flow, and waves There are factors. When using a mechanical measurement method using a physical structure, these not only cause many problems, but also hinder the operation of charter vessels used in construction. Furthermore, since it is in seawater, it is affected by the attenuation of radio waves and the reflection of sound waves (due to bubbles, etc.), which makes it impossible to use general wireless telemeters and measuring means using ultrasonic waves. In this respect, conditions in the landslide area on land are similar, and it is difficult to use radio waves, ultrasonic waves, light, or the like as means for measuring the inside of the ground and the ground surface.

  An object of the present invention is to provide a position measurement method that can accurately capture the amount of lateral movement and the direction of movement in the sea or soil in a landfill site or a wide landslide area as described above.

  According to the first aspect of the present invention, a transmitter embedded with a single-axis coil that is buried in the ground or in the seabed ground and generates an alternating magnetic field, and disposed near the ground surface or the sea surface to receive the alternating magnetic field. Detection including first and second coils spaced apart on a first axis and third and fourth coils spaced apart on a second axis perpendicular to the first axis A magnetic field strength obtained from the outputs of the first to fourth coils, and based on the magnetic field strength obtained by the first to fourth coils, the position of the axis of the single-axis coil and the detection coil system There is provided a position measurement method characterized in that the relative position of the center is obtained two-dimensionally.

  In the position measurement system according to the first aspect, it is preferable that the detection coil system is arranged so that the axes of the first to fourth coils are parallel or perpendicular to the axis of the single-axis coil.

  In the position measurement method according to the first aspect, each of the first to fourth coils may be a three-component coil whose axes are orthogonal to each other.

  In the position measurement method according to the first aspect, each of the first to fourth coils may be a plurality of coils.

  According to the second aspect of the present invention, a transmitter embedded with a single-axis coil that is buried in the ground or in the seabed ground and generates an alternating magnetic field, and disposed near the ground surface or the sea surface to receive the alternating magnetic field. Detection including first and second coils spaced apart on a first axis and third and fourth coils spaced apart on a second axis perpendicular to the first axis A coil system, first to fourth bandpass filters that receive the outputs of the first to fourth coils, and a first that outputs the difference signal in response to the outputs of the first and second bandpass filters A differential circuit; a second differential circuit that receives the outputs of the third and fourth bandpass filters and outputs a difference signal; and a first differential circuit that receives the outputs of the first and second differential circuits, respectively. And a signal processing circuit system including a second phase detection circuit, And the second phase detection circuit receives the output of any of the first to fourth bandpass filters as a detection signal and performs synchronous detection, and the first and second phase detection circuits in the upper region of the single-axis coil. A position measurement method is provided, wherein the center position of the detection coil system when the output of the phase detection circuit is minimized is obtained as a position immediately above the single-axis coil.

  In the position measurement method according to the second aspect, the detection coil system further includes a fifth coil installed on a third axis orthogonal to the first axis and the second axis, and the signal processing circuit system includes Furthermore, it is preferable to have a fifth bandpass filter that receives the output of the fifth coil, and to use the output of the fifth bandpass filter as the detection signal of the first and second phase detection circuits.

  In the position measurement method according to the second aspect, the first to fourth coils, which are installed at intervals on the first axis and the second axis, are each two, and each of these two coils. By connecting the output to the input of the corresponding bandpass filter using a switching circuit and performing synchronous detection using the output of the fifth coil as the detection signal, two types of outputs can be used per axis.

  According to the third aspect of the present invention, a transmitter having a single-axis electrode pair embedded in the ground or in the seabed ground to generate an electric field, and disposed near the ground surface or the sea surface to detect the electric field. Detection comprising first and second electrodes spaced apart on a first axis and third and fourth electrodes spaced apart on a second axis perpendicular to the first axis An electrode system; a first differential circuit that receives the outputs of the first and second electrodes and outputs a difference signal; and a second that receives the outputs of the third and fourth electrodes and outputs a difference signal Differential circuit, first and second band-pass filters receiving the outputs of the first and second differential circuits, and first and second receiving the outputs of the first and second band-pass filters, respectively. A signal processing circuit system including a second phase detection circuit, and the first and second phase detection circuits are Synchronous detection is performed by receiving the output of any of the first to fourth electrodes as a detection signal, and the outputs of the first and second phase detection circuits are minimized in the region above the uniaxial electrode pair. A position measuring method is provided, wherein the center position of the detection electrode system at the time is obtained as a position immediately above the uniaxial electrode pair.

  In the position measurement method according to the third aspect, the detection electrode system further includes a fifth electrode composed of a pair of electrodes disposed on a third axis orthogonal to the first axis and the second axis, The signal processing circuit further includes a third differential circuit that receives the output of the fifth electrode pair and outputs a difference signal, and a third bandpass filter that receives the output of the third differential circuit. Preferably, the output of the third bandpass filter is used as a detection signal of the first and second phase detection circuits.

In the position measurement method according to the third aspect, the detection electrode system includes two each of the first to fourth electrodes that are installed at intervals on the first axis and the second axis, respectively, In the signal processing circuit system, these two electrode outputs are output to the differential circuit, and two difference signals of the two electrode outputs on the first axis are input to the first differential circuit. , By inputting two difference signals of two electrode outputs on the second axis to the second differential circuit, and performing synchronous detection using the output of the third bandpass filter as a detection signal, Two types of outputs can be used per axis.
[Operation of the invention]

  In the measurement method described above, the magnetic field or electric field generated by a single-axis coil or electrode pair (hereinafter referred to as a transmission system) on the ground or the seabed is symmetrical with respect to the axis of the single-axis transmission system. It is formed. In the magnetic field method, the magnetic field component is obtained as a voltage signal by a plurality of coils arranged on the horizontal axis as a position detection signal, and in the electric field method, the electric field strength (distribution) is obtained by a plurality of electrodes arranged on the horizontal axis. It is obtained as a voltage signal. These voltage signals differ in phase from the point just above the single-axis transmission system, so if phase detection (synchronous detection) is performed, the polarity or the coil or electrode from the point just above the single-axis transmission system can be discriminated. As a result, the horizontal coordinate immediately above the uniaxial transmission system can be obtained.

  According to the present invention, it is easy to obtain the coordinates directly above by detecting a magnetic field component and an electric field component formed by a transmitter having a single-axis coil installed in the ground using a coil or an electrode. It becomes possible. As a result, it is possible to easily measure the lateral movement (flow) of the submarine ground in burial work such as offshore airport construction, and the amount of movement of the clumps above the slip surface in the land landslide area. The effect obtained is great.

  Embodiments of a position measurement method according to the present invention will be described below with reference to the drawings.

(Magnetic field method)
FIG. 1 is a diagram showing the arrangement of coils in the first embodiment when the present invention is applied to a magnetic field system. A transmitter 10 including an oscillator 11 and a single-axis coil (transmission coil) 12 is embedded in the ground. By applying AC power output from an oscillator 11 connected to a power source (not shown) such as a battery built in the transmitter 10 to the single-axis coil 12, the single-axis coil 12 is excited, and an induction magnetic field (alternating magnetic field) ) Is formed. In particular, it is preferable to generate a magnetic field signal called a low-frequency magnetic field signal of about 1 kHz to 10 kHz by a combination of a power source, an oscillator, and a single-axis coil and transmit it through a transmission antenna. The low-frequency magnetic field signal has a characteristic that it propagates even in a transmission medium that is difficult to transmit electromagnetic waves and ultrasonic waves, such as underground, underwater, and rock. This can be applied to all magnetic field embodiments described below.

  On the other hand, in order to detect the low frequency magnetic field signal, first to fourth detection coils CA to CD are arranged near the ground surface or the sea surface. In the first to fourth detection coils CA to CD, the detection coils CA and CC are arranged concentrically with an interval on the first axis S1, and the detection coil CB with the same interval on the second axis S2. And CD are arranged concentrically. It is desirable that the first axis S1 and the second axis S2 and the extension axis of the single axis coil 12 are arranged orthogonal to each other. A nonmagnetic rod or hollow material is used as the material forming the first axis S1 and the second axis S2. The detection coils CA and CC correspond to the first and second coils described in the claims, and the detection coils CB and CD correspond to the third and fourth coils described in the claims. To do. In the following description of all the embodiments, such a plurality of detection coils may be collectively referred to as a detection coil system.

  FIG. 2 is a block diagram showing a configuration of a signal processing circuit system for the detection coil system of FIG. The outputs of the detection coils CA to CD are amplified by the amplifiers 15A to 15D, respectively, and then a single frequency component that is the same as the oscillation frequency of the oscillator 11 is extracted by the band-pass filters 16A to 16D. Subsequently, a difference signal between the detection coils CA and CC on the first axis S1 and a difference signal between the detection coils CB and CD on the second axis S2 are formed by the differential circuits 17-1 and 17-2, respectively. Input to the phase detection circuits 18-1 and 18-2. Here, the output of one of the detection coils in the detection coil system can be used as the detection signal in the phase detection circuits 18-1 and 18-2. In FIG. 2, a signal from the detection coil CA system is used as a detection signal, but any one of the four detection coils may be arbitrarily selected by a changeover switch. Needless to say, the bandpass filter, the differential circuit, and the phase detection circuit can obtain the same result by computer processing using digital operations such as an A / D converter and FFT operation, in addition to the method in which the analog circuit is configured.

  FIG. 3 is a sectional view showing the arrangement of the transmitter and the detection coil in the first embodiment of the present invention. When the transmitter is buried, the position is measured in advance as an initial position. The induction magnetic field component formed by the single-axis coil 12 embedded in the ground also spreads on the ground surface or the sea surface, and two detection coils (combinations of CA and CC, formed on the first axis S1 of the detection coil system, Alternatively, an alternating voltage is induced in the detection coil when linked to a combination of CB and CD. Here, regarding the combination of the two detection coils CA and CC, if the horizontal movement is performed with these intervals kept constant, the amplitude of the AC voltage induced in the two detection coils changes. If the intermediate point between the two detection coils (CA and CC) comes directly above the single-axis coil 12, the AC voltages induced in these two detection coils have the same amplitude although they have different polarities. The output of the device 18-1 is the minimum value. At this time, the one-dimensional coordinates immediately above the single-axis coil 12 are obtained as coordinates orthogonal to the paper surface passing through the midpoint between the two detection coils (CA and CC). Other one-dimensional coordinates are similarly obtained by two detection coils (CB and CD) installed on the second axis S2.

  The initial position is set by the following two methods. The first method is applied, for example, when measuring the amount of landslide movement described later, and is based on the assumption that the ground in which the transmitter 10 is embedded does not move. In this case, the transmitter 10 is embedded in the ground deeper than the predicted landslide part in the landslide zone, and marking is performed on the buried ground surface. When a landslide occurs, the marked ground surface moves, but the position of the transmitter 10 does not change. Therefore, the detection coil system is moved from the marked location to search for a position where the outputs of the phase detectors 18-1 and 18-2 are minimum values. The searched position is a position directly above the transmitter 10, and the distance between this position and the marking position after the occurrence of the landslide is a shift amount (movement amount), and the direction of the line segment connecting the two becomes the movement direction.

  The second method is applied, for example, when measuring the amount of lateral movement of the seabed ground described later, and is based on the assumption that the ground in which the transmitter 10 is embedded moves. In this case, the transmitter 10 is embedded in the seabed ground where lateral movement is predicted, and the position immediately above the embedded position (directly above the sea surface) is measured as the initial position by a method such as GPS. The position of the transmitter 10 changes when there is a lateral movement on the seabed ground. Therefore, the detection coil system is moved from the initial position in the vicinity of the sea surface to search for a position where the outputs of the phase detectors 18-1 and 18-2 are minimum values. The searched position is a position immediately above the transmitter 10. If this position is measured by a method such as GPS, the distance between the measured position and the initial position is the amount of movement, and the direction of the line segment connecting the two is It becomes the moving direction.

  Depending on what is measured, the setting method as described above is applied to all embodiments described below.

  From the above operation principle, the single-axis coil 12 needs to be installed such that its axis is in the vertical direction, and the detection coil system has the first axis S1, the second axis S2, that is, the axis of each detection coil. It is preferable that the detection operation is performed in a state where the surface is on a horizontal plane perpendicular to the vertical direction. Further, the constituent elements of the transmitter 10 are housed in a watertight case, and in the case of battery power instead of external power, the oscillator 11 is not continuously oscillated but intermittently by means such as a timer. Needless to say, it is preferable that the operation is performed automatically. These points are the same in any of the embodiments described later.

  FIG. 4 is a diagram showing a coil arrangement in the second embodiment of the present invention. By applying an alternating current output from the oscillator 11 of the transmitter 10 buried in the ground to the single axis coil 12, the single axis coil 12 is excited and an induction magnetic field is formed. The first to fourth detection coils CA to CD arranged near the ground surface or the sea surface are the same as those shown in FIG. On the other hand, in FIG. 4, a third axis S3 orthogonal to the first axis S1 and the second axis S2 is provided, and a detection coil system in which a fifth detection coil CE is arranged on the third axis S3 is configured.

  The reason why the fifth detection coil CE is provided is as follows. The first to fourth detection coils CA to CD in the figure are placed near the ground surface or the sea surface, and depending on their positions, the magnetic field created by the single-axis coil 12 is not linked to the detection coil at all. There is. That is, when measurement is performed with the coil arrangement of FIG. 1 and the circuit configuration of the block diagram shown in FIG. 2, it is assumed that a state in which no detection signal is obtained from the detection coil CA occurs. In order to solve this problem, a fifth detection coil CE is provided on the third axis S3 having a sensitivity axis different from that of the four detection coils CA to CD, and a signal obtained from the detection coil CE is used as a detection signal. Thus, it is possible to prevent the absence of the detection signal as described above.

  FIG. 5 is a block diagram showing a signal processing circuit system for the detection coil system of FIG. The outputs of the detection coils CA to CD are amplified by the amplifiers 15A to 15D, respectively, and then a single frequency component same as the frequency of the oscillator 11 is extracted by the band pass filters 16A to 16D. Subsequently, a difference signal between the detection coils CA and CC on the first axis S1 and a difference signal between the detection coils CB and CD on the second axis S2 are generated by the differential circuits 17-1 and 17-2, respectively. The detected signals are input to the detection circuits 18-1 and 18-2. In the block diagram shown in FIG. 2, the detection signals of the phase detection circuits 18-1 and 18-2 are obtained from any one of the detection coils CA to CD, but in FIG. 5, the signal from the fifth detection coil CE is detected. Used as a signal.

  FIG. 6 is a sectional view showing the coil arrangement in the second embodiment of the present invention. 3 is different from the coil arrangement of FIG. 3 in that a fifth detection coil CE having a sensitivity axis different from that of the first to fourth detection coils CA to CD is arranged by 90 degrees. In the upper region of the coil (transmission coil) 12, a magnetic signal is always received regardless of its position.

  FIG. 7 is a view showing the arrangement of coils in the third embodiment of the present invention. The point that a magnetic field is formed by the single-axis coil 12 in the transmitter 10 embedded in the ground is the same as in FIG. There are four detection coils (CA1, CA2, CC1, CC2) on the first axis S1 and four detection coils (CB1, CB2, CD1, CD2) on the second axis S2 The arrangement is such that a total of nine (CE) is used for the third axis S3 orthogonal to the axis S1 and the second axis S2. Of course, the distance between the detection coils CA1 and CA2, the distance between the detection coils CC1 and CC2, the distance between the detection coils CB1 and CB2, and the distance between the detection coils CD1 and CD2 are made the same, and the set of the detection coils CA1 and CA2 and the detection coil CC1, The interval between the sets of CC2 and the interval between the sets of detection coils CB1 and CB2 and the sets of detection coils CD1 and CD2 are also made the same. In the drawing, the detection coils are shown as two combinations of CA1 and CA2, but three combinations such as CA1, CA2 and CA3 can be used, and the number of detection coils can be increased. Since the distance between the coils can be wide, it is advantageous in measurement.

  FIG. 8 is a block diagram showing a configuration of a signal processing circuit system for the detection coil system of FIG. In the signal processing circuit system of FIG. 8, since the detection coil which the amplifier is responsible for has two systems, switching circuits 19A to 19D are arranged on the input sides of the amplifiers 15A to 15D, respectively. However, these switching circuits 19A to 19D do not perform switching separately, but either one of the detection coil CA1, CB1, CC1, CD1 or the detection coil CA2, CB2, CC2, CD2 is set. It is preferably used to select. The circuit and operation after the amplifier are exactly the same as those of the signal processing circuit system of FIG. If no switching circuit is used, the same result can be obtained by using the same number of amplifiers, band-pass filters, etc. as the detection coil in parallel.

  FIG. 9 is a sectional view showing a coil arrangement in the third embodiment of the present invention. 6 and 9 is that detection coils CA2 to CD2 having sensitivity axes in the horizontal direction are added to detection coils CA1 to CD1 having sensitivity axes in the horizontal direction. By arranging the detection coils at two positions on both sides of the detection coil CE having the sensitivity axis in the vertical direction, there is an advantage that it is easy to obtain the horizontal coordinate immediately above the single-axis coil 12. In particular, when the distance between the single-axis coil 12 and each detection coil is large, there is an effect in that the directivity of the coordinates immediately above the single-axis coil 12 can be found quickly after starting the measurement operation.

(Electric field method)
FIG. 10 is a diagram showing the arrangement of electrodes in a fourth embodiment in which the present invention is applied to an electric field system. An electric field is formed between the uniaxial electrodes E1 and E2 by applying an alternating current output from the oscillator 11 in the transmitter 10 buried in the ground between the two uniaxial electrodes E1 and E2 ( Current flows). The first to sixth detection electrodes EA, EB, EC, ED, EE, and EF disposed near the ground surface or the sea surface are for detecting the electric potential of the electric field by the electrodes E1 and E2, and have a first axis S1. The detection electrodes EA and EC are spaced apart from each other, the detection electrodes EB and ED are disposed at the same spacing on the second axis S2, and the third axis S3 is orthogonal to the first axis S1 and the second axis S2. The detection electrodes EE and EF are arranged on the top. Here, as in the case of the magnetic field method, the transmitter 10 is installed so that the axes of the single-axis electrodes E1 and E2 are in the vertical direction, and the first axis S1 and the second axis S2 are also orthogonal to each other. It is desirable. Further, an insulating rod or a hollow material is used as the material forming the first axis S1 to the third axis S3. The detection electrodes EA to ED are used to detect coordinates and directions immediately above the two single-axis electrodes E1 and E2, and the detection electrodes EE and EF are used to obtain detection signals used for phase detection. The detection electrodes EA and EC correspond to the first and second electrodes described in the claims, and the detection electrodes EB and ED correspond to the third and fourth electrodes described in the claims. To do. In the following description, such a plurality of detection electrodes may be collectively referred to as a detection electrode system.

  FIG. 11 is a block diagram showing a configuration of a signal processing circuit system for the detection electrode system of FIG. The potentials detected by the detection electrodes EA to EF are different from each other for each electrode combination (EA and EC, EB and ED, and EE and EF) arranged on each axis. , 20-2 and 20-3 are detected as differential potentials. From these difference signals, a detection signal is generated by the detection electrodes EA to ED, and a detection signal is generated by the detection electrodes EE and EF. The same frequency components as the oscillation frequency of the oscillator 11 are extracted from the difference signals of the differential circuits 20-1 to 20-3 by the band-pass filters 21-1 to 21-3. The phase detection circuits 22-1 and 22-2 receive the signals of the bandpass filters 21-1 and 21-2, perform synchronous detection using the signals of the bandpass filter 21-3 as detection signals, The potential difference in the biaxial S2 direction is output. As in the case of the magnetic field method, the potential difference becomes the minimum value when the center of the detection electrode system is positioned on the axes of the uniaxial electrodes E1 and E2. In addition to the method of configuring these circuits with analog circuits, the same effect can be obtained by computer processing by converting them into digital values using an A / D converter.

  FIG. 12 is a sectional view showing an electrode arrangement in the fourth embodiment of the present invention. The electric field (current) component formed by the uniaxial electrode E1-E2 embedded in the ground is greatly bent near the surface of the earth or the sea surface and spreads radially on the surface starting from the uniaxial electrode E1-E2 immediately above. The potential of these components is detected by a plurality of detection electrodes arranged below the surface, and is detected as a potential difference by obtaining a difference signal of the detection electrodes between two points separated on the same axis. From this, when two detection electrodes having the same interval are arranged on two intersecting axes, a two-dimensional potential difference is detected, and when the potential difference is minimized, the middle point of the two detection electrodes is a single-axis electrode E1-E2. Will match directly above. Since phase detection is used, noise components can be removed at the same time by using the same frequency component as an AC electric field formed by a single-axis electrode as a detection signal.

  The third axis S3 and the detection electrodes EE and EF may be omitted. In this case, the detection signal uses the output of any of the detection electrodes EA to ED.

  FIG. 13 is a diagram showing a fifth embodiment when the present invention is applied to the measurement of landslide movement. Boring is performed in a region where landslide is expected to occur, and a transmitter 10 including an oscillator 11 and a single-axis coil 12 is installed at a depth below the predicted slip surface. Here, the trace of the boring hole 45 can be used as the marking of the first setting method in the initial position setting described above. As described above, the transmitter 10 can prevent the built-in battery from being exhausted by starting the oscillator 11 at a predetermined time and generating a magnetic field from the single-axis coil 12 by the built-in timer. Further, in the case of the magnetic field system, the single-axis coil 12 for generating a magnetic field incorporated in the transmitter 10 is also used as a reception coil, and a reception circuit is combined with the single-axis coil 12 and a start signal is generated by a magnetic signal from the ground surface. It is also possible to start the oscillator 11 by giving. Details of these methods are disclosed in Patent Documents 2 and 3, for example.

  The amount of landslide movement after the transmitter 10 is buried is measured as follows. A side line is set on the ground surface by a moving table 41 made of a nonmagnetic material on the ground, and the detection coil system 40 can be moved along the side line. The movable table 41 is preferably constructed so that the level is maintained.

  In the case of the first embodiment, the detection coil system 40 is horizontally moved with reference to the marking location, and a position where the outputs of the phase detectors 18-1 and 18-2 are minimum is searched. If there is no landslide, the outputs of the phase detectors 18-1 and 18-2 are minimum values at the marking location. On the other hand, if the movement due to the landslide has occurred, the outputs of the phase detectors 18-1 and 18-2 become the minimum value at a certain place moved in the horizontal direction from the marking place, that is, a position immediately above the transmitter 10. The distance between this search position and the marking position after the occurrence of a landslide is the shift amount (movement amount), and the direction of the line segment connecting the two is the movement direction.

  All the embodiments described above can be applied to the detection coil system 40 and the signal processing circuit system. However, in the case of the electric field method, it goes without saying that the detection electrode system and the signal processing circuit system shown in FIGS. 10 and 11 are used.

  FIG. 14 is a diagram showing a sixth embodiment in the case where the present invention is applied to landfill work such as a harbor. In the construction of the offshore airport, the airport facilities are constructed on the artificial ground formed by landfill in the port near the land. When this earth and sand reclamation is performed, lateral movement due to the reclamation load occurs on the seabed near the landfill area. In order to measure the amount of movement, a transmitter 10 for generating an alternating magnetic field is installed in the seabed ground to generate a magnetic field in the sea. On the other hand, a detection coil system 40 is arranged in seawater using a float 50 or the like near the sea surface, and a GPS receiver 51 is installed in the float 50. The position of the GPS receiver 51 can be easily obtained by GPS or optical surveying, and has already been put into practical use.

  Also in the sixth embodiment, any of the first to fifth embodiments described above may be applied to the detection coil system (detection electrode system) and the signal processing circuit system. Needless to say, the wire portion connecting the float 50 and the detection coil system 40 is used together with a device for preventing the wavefront motion from being transmitted using a spring, a plate or the like (not shown). In addition, the detection coil system (detection electrode system) may be arranged at all times, but may be pulled up when the measurement is not performed and dumped on the sea during the measurement. In any case, the detection signal from each detection coil (detection electrode) is input to the signal processing circuit system on the ship via a cable via the float 50, but the amplifier may be provided on the float 50 side.

  In the sixth embodiment, the initial position when the transmitter 10 is embedded using the GPS receiver 51 is measured in advance. Thereafter, the transmitter 10 is periodically activated, the detection coil system 40 is moved, and the work of measuring the position of the transmitter 10 two-dimensionally is performed. For example, when the detection coil system and the signal processing circuit system according to the first embodiment are used, the output of the phase detectors 18-1 and 18-2 is minimized if a lateral movement occurs in the seabed ground. The position will also deviate from the initial position. According to the GPS receiver 51, since the current position deviated from the initial position can be known, the horizontal movement amount and movement direction of the seabed ground can be easily determined from the initial position and the current position on the biaxial coordinate plane. Can be calculated.

  FIG. 15 is a diagram showing the arrangement of electrodes in the seventh embodiment of the present invention. An electric field is formed between the electrodes E1 and E2 by applying an alternating current (voltage) output output from the oscillator 11 in the transmitter 10 embedded in the ground to the uniaxial electrodes E1 and E2. Here, the detection electrode system is configured by arranging pairs of electrodes at equal intervals, and the first to fifth detection electrode pairs EG to EK are arranged near the ground surface or the sea surface. Specifically, the first and third electrode pairs EG and EI on the first axis S1, the second and fourth electrode pairs EH and EJ on the second axis S2, and the first axis S1 and the second axis. The fifth electrode pair EK is arranged on the third axis S3 orthogonal to S2. As described above, it is desirable that the axes of the electrodes E1 and E2 are in the vertical direction, and the first axis S1 and the second axis S2 are arranged orthogonal to each other.

  FIG. 16 is a block diagram showing a configuration of a signal processing circuit system for the detection electrode system of FIG. First, the differential potentials 61G to 61K are extracted from the potentials of the respective pairs detected by the respective detection electrode pairs EG to EK. Next, the differential circuits 62-1 and 62-2 use the difference potential between the difference potential of the first electrode pair EG and the difference potential of the third electrode pair EI, the difference potential of the second electrode pair EH, and the fourth difference. The difference potential with respect to the difference potential of the electrode pair EJ is taken out and detected as the difference potential of each axis. The same frequency component as the oscillation frequency of the oscillator 11 is extracted from the difference potential between the first axis S1 and the second axis S2 by the bandpass filters 63-1 and 63-2, and the bandpass filter 63- from the difference potential of the differential circuit 61K. 3 extracts the same frequency component as the oscillation frequency of the oscillator 11. In this way, a detection signal is generated by the first electrode pair EG to the fourth electrode pair EJ, and a detection signal is generated by the fifth electrode pair EK. The two sets of phase detection circuits 64-1 and 64-2 receive these signals, perform synchronous detection, and output a potential difference between the first axis S1 direction and the second axis S2 direction.

  FIG. 17 is a sectional view showing the electrode arrangement of the detection electrode system in the seventh embodiment of the present invention. The electric field (current) component formed by the uniaxial electrodes E1 and E2 embedded in the ground is greatly bent near the surface of the earth or the sea surface, and spreads radially on the surface starting from directly above the uniaxial electrode. These electric field components are detected as a potential difference by detecting a potential by a detection electrode system disposed below (in the vicinity of) the water surface and obtaining a difference signal between two pairs of electrodes on the same axis. Therefore, when electrode pairs with the same interval are arranged on two intersecting axes, a two-dimensional potential difference is detected. When this potential difference is minimized, the intermediate point between two electrode pairs on one axis is a single axis. It is located immediately above the electrodes E1 and E2.

  FIG. 18 is a diagram showing an eighth embodiment when the present invention is applied to land reclamation work such as a harbor. When the detection coil system (or detection electrode system) is placed near the sea surface, if it is hung from the ship, the movement of the ship due to waves will be transmitted to the detection coil system (or detection electrode system), and movement (displacement) will always be transmitted. Stable measurement (measurement) is difficult. In order to solve this problem, in this embodiment, one or more (two in this case) elastic members 55 such as springs are interposed between the float 50 and the detection coil system 40 (or the detection electrode system), and 2 A plate 56 that receives water resistance is used between the two elastic members 55. Thereby, the detection coil system 40 (or the detection electrode system) can be stably maintained in water, and an effect of reducing the influence of waves can be obtained. As a means for moving the frame for fixing the detection coil system and the detection electrode system, the ship may be towed, but a motor, a screw and a rudder may be attached to the float 50 and remote control may be performed from the ship. . In order to easily perform remote control, a GPS receiver 51, an azimuth meter, etc. are attached to the float 50, and it is easy to improve workability by performing work while constantly monitoring the coordinate information of the float 50 on the ship. Become. In this embodiment, any of the first to fourth and seventh embodiments described above may be applied.

  FIG. 19 is a diagram for explaining that the detection output of the magnetic field signal obtained from the detection coil used in the present invention changes depending on the directionality and relative position of the detection coil with respect to the single-axis coil. In FIG. 19, the magnetic field strength is obtained from the output of the detection coil on the assumption that the transmission-side single-axis coil is arranged at a distance e immediately below the zero point. The characteristic (a) in FIG. 19 shows the magnetic field intensity distribution measured when the detection coil whose detection maximum sensitivity axis is in the vertical direction is moved in the horizontal direction, and it is clear that the maximum is directly above the single axis coil. is there. On the other hand, the characteristic (b) of FIG. 19 shows the magnetic field strength distribution measured when the detection coil (corresponding to each embodiment of the present invention) whose detection maximum sensitivity axis is in the horizontal direction is moved. Here, the region in which the characteristic (b) is negative in the left half of the figure is generated because the calculation is performed in consideration of the phase component of the received signal. The horizontal axis in FIG. 19 represents the distance e to the center of the transmission-side single-axis coil. Such a magnetic field strength distribution or magnetic field distribution (spreading) can also be obtained by calculation.

  FIG. 20 is a diagram showing the result of differentiating the output of the magnetic field signal detected by the detection coil used in the present invention. When differential calculation processing is performed on the characteristics (a) and (b) obtained in FIG. 19, the characteristic (a) in FIG. 19 becomes the characteristic (c) in FIG. 20, and the characteristic (b) in FIG. This is shown as characteristic (d) in FIG. The point to be noted here is that characteristics (c) and (d) intersect at the position on the left side in the figure, and the coordinate of the intersection is 0.21e, that is, 21% of the distance e to the center of the single-axis coil on the transmission side. It is equivalent to. This means that both the detection coil having the maximum sensitivity on the horizontal axis and the detection coil having the maximum sensitivity on the vertical axis are used together, and the above value 0.21e is used as the switching position for selecting the higher signal level. This is a measurement advantage.

  FIG. 21 shows a specific example of the detection coil system used in the present invention. A shaft S1-1 and a shaft S1-2 are attached to the fixed portion 100 to constitute a first shaft, and a shaft S2-1 and a shaft S2-2 are attached to constitute a second shaft. The fixed part 100 and each shaft are made of a non-magnetic material such as vinyl chloride or acrylic and a non-conductive material. Since the detection coils CA to CD can be installed by post-processing after attaching the respective shafts to the fixed portion 100, the merit in manufacturing including waterproof processing is great. Although this example is suitable for the detection coil system shown in FIG. 1, the fixed portion 100 is hollow and the detection coil is built in, and the axis of this coil is the axis of the detection coils CA and CC, the detection coils CB and CD. The detection coil system shown in FIG. 4 can be realized by arranging so as to be orthogonal to the axis. Of course, the detection coil system shown in FIG. 7 can be realized by installing a plurality of detection coils on each axis.

  FIG. 22 shows another example of the detection coil system used in the present invention. In this example, a cubic lattice-shaped frame 110 is used, and detection coils C1, C2, and C3 are installed at each corner portion. The material of the frame 110 is preferably a non-magnetic material such as vinyl chloride or acrylic and a non-conductive material, as in the example of FIG. 21 described above. Speaking of one corner, it can be regarded as a three-component coil in which detection coils are installed on three axes of X axis, Y axis, and Z axis orthogonal to each other. By providing switching means for switching these three component coils for each corner, it is possible to arbitrarily select which detection coil is used for detection. If the upper or lower detection coil in the figure is used, a planar detection coil system can be configured, and if both the upper and lower detection coils are used, a three-dimensional detection coil system can be configured. By using such a cubic lattice-shaped frame body 110, it becomes easy to ensure stability even when installed on the ground in addition to underwater. As an example, as shown by the alternate long and short dash line in the figure, a further intersecting frame is provided in the quadrangular frame forming the frame 110, and a detection coil is installed in the intersecting frame as shown in FIG. It goes without saying that a detection coil system that also serves as a detection coil system can be realized.

FIG. 1 is a diagram showing the arrangement of coils in the first embodiment when the present invention is applied to a magnetic field system. FIG. 2 is a block diagram showing a configuration of a signal processing circuit system for the detection coil system of FIG. FIG. 3 is a sectional view showing the arrangement of the transmitter and the coil in the first embodiment of the present invention. FIG. 4 is a diagram showing the coil arrangement in the second embodiment when the present invention is applied to a magnetic field system. FIG. 5 is a block diagram showing a configuration of a signal processing circuit system for the detection coil system of FIG. FIG. 6 is a sectional view showing the arrangement of the transmitter and the coil in the second embodiment of the present invention. FIG. 7 is a diagram showing the coil arrangement in the third embodiment when the present invention is applied to a magnetic field system. FIG. 8 is a block diagram showing a configuration of a signal processing circuit system for the detection coil system of FIG. FIG. 9 is a sectional view showing the arrangement of the transmitter and the coil in the third embodiment of the present invention. FIG. 10 is a diagram showing the arrangement of electrodes in the fourth embodiment when the present invention is applied to an electric field system. FIG. 11 is a block diagram showing a configuration of a signal processing circuit system for the detection electrode system of FIG. FIG. 12 is a cross-sectional view showing the arrangement of a transmitter and electrodes in the fourth embodiment of the present invention. FIG. 13 is a diagram showing a fifth embodiment when the present invention is applied to the measurement of landslide movement. FIG. 14 is a diagram showing a sixth embodiment in the case where the present invention is applied to landfill work such as a harbor. FIG. 15 is a diagram showing the arrangement of electrodes in the seventh embodiment when the present invention is applied to an electric field system. FIG. 16 is a block diagram showing a configuration of a signal processing circuit system for the detection electrode system of FIG. FIG. 17 is a cross-sectional view showing the arrangement of the transmitter and electrodes in the seventh embodiment of the present invention. FIG. 18 is a diagram showing an eighth embodiment when the present invention is applied to land reclamation work such as a harbor. FIG. 19 is a diagram for explaining that the detection output of the magnetic field signal obtained from the detection coil used in the present invention changes depending on the directionality and relative position of the detection coil with respect to the single-axis coil. FIG. 20 is a diagram showing a result of differentiating the output of the magnetic field signal shown in FIG. FIG. 21 is a diagram showing a specific example of the detection coil system used in the present invention. FIG. 22 is a diagram showing another example of the detection coil system used in the present invention.

Explanation of symbols

CA, CB, CC, CD, CE Detection coils S1, S2, S3 1st axis, 2nd axis, 3rd axis EA, EB, EC, ED, EE, EF Detection electrode 15A-15E Amplifier 16A-16E Band pass filter 17-1, 17-2 Differential circuit 18-1, 18-2 Phase detector

Claims (12)

A transmitter with a built-in single-axis coil that is buried in the ground or in the seabed and generates an alternating magnetic field, and a first shaft that is placed near the surface of the earth or near the sea surface to receive the alternating magnetic field. A detection coil system including first and second coils and third and fourth coils spaced apart on a second axis orthogonal to the first axis;
The magnetic field strength is obtained from the outputs of the first to fourth coils, and the position of the axis of the single-axis coil and the relative position of the center of the detection coil system are determined based on the magnetic field strength obtained from the first to fourth coils. A position measurement method characterized by dimensional determination.   2. The position measuring method according to claim 1, wherein the detection coil system is arranged so that the axes of the first to fourth coils are parallel or perpendicular to the axis of the single-axis coil. Measurement method.   2. The position measuring method according to claim 1, wherein each of the first to fourth coils includes a three-component coil whose axes are orthogonal to each other.   2. The position measuring method according to claim 1, wherein each of the first to fourth coils is a plurality of coils. A transmitter with a built-in single-axis coil that is buried in the ground or in the seabed and generates an alternating magnetic field;
In order to receive the alternating magnetic field, the first and second coils arranged at a distance on the first axis arranged near the ground surface or the sea surface and the second axis orthogonal to the first axis are spaced apart. A detection coil system including third and fourth coils installed
First to fourth bandpass filters that receive the outputs of the first to fourth coils; and a first differential circuit that receives the outputs of the first and second bandpass filters and outputs a difference signal; A second differential circuit that receives the outputs of the third and fourth bandpass filters and outputs a difference signal; and first and second differential circuits that receive the outputs of the first and second differential circuits, respectively. A signal processing circuit system including a phase detection circuit,
The first and second phase detection circuits receive the output of any of the first to fourth bandpass filters as a detection signal, perform synchronous detection,
A position in which the center position of the detection coil system when the outputs of the first and second phase detection circuits are minimized in the upper region of the single axis coil is determined as a position immediately above the single axis coil. Measurement method.   6. The position measurement method according to claim 5, wherein the detection coil system further includes a fifth coil installed on a third axis orthogonal to the first axis and the second axis, and the signal processing circuit system is And a fifth bandpass filter for receiving the output of the fifth coil, wherein the output of the fifth bandpass filter is used as a detection signal of the first and second phase detection circuits. Position measurement method to do.   7. The position measuring method according to claim 6, wherein two each of the first to fourth coils respectively installed at intervals on the first axis and the second axis are provided, and each of the two coil outputs is provided. Is connected to the input of the corresponding band-pass filter using a switching circuit, and synchronous detection is performed using the output of the fifth coil as a detection signal, so that two types of outputs are used per axis. Measurement method. A transmitter having a single-axis electrode pair embedded in the ground or in the seabed and generating an electric field;
In order to detect the electric field, the first and second electrodes arranged on the first axis disposed near the ground surface or near the sea surface are spaced apart from each other on the second axis orthogonal to the first axis. A sensing electrode system comprising third and fourth electrodes installed
A first differential circuit that receives the outputs of the first and second electrodes and outputs a difference signal, and a second differential circuit that receives the outputs of the third and fourth electrodes and outputs a difference signal First and second bandpass filters that receive the outputs of the first and second differential circuits, and first and second phase detectors that receive the outputs of the first and second bandpass filters, respectively. And a signal processing circuit system including a circuit,
The first and second phase detection circuits receive the output of any of the first to fourth electrodes as a detection signal, perform synchronous detection,
Obtaining the center position of the detection electrode system as the position immediately above the uniaxial electrode pair when the outputs of the first and second phase detection circuits are minimized in the upper region of the uniaxial electrode pair. Characteristic position measurement method.   6. The position measurement system according to claim 5, wherein the detection electrode system further includes a fifth electrode including a pair of electrodes disposed on a third axis orthogonal to the first axis and the second axis, The signal processing circuit system further includes a third differential circuit that receives the output of the fifth electrode pair and outputs a difference signal, and a third band-pass filter that receives the output of the third differential circuit. And a position measuring method using the output of the third bandpass filter as a detection signal of the first and second phase detection circuits.   10. The position measurement method according to claim 9, wherein the detection electrode system includes two each of the first to fourth electrodes installed at intervals on the first axis and the second axis, respectively. In the processing circuit system, these two electrode outputs are output to the differential circuit, and two difference signals of the two electrode outputs on the first axis are input to the first differential circuit, Two differential signals of two electrode outputs on the second axis are input to the second differential circuit, and synchronous detection is performed using the output of the third bandpass filter as a detection signal. A position measurement method characterized by using two types of outputs per unit. A method for measuring a moving amount and a moving direction due to a landslide on land using the position measurement method according to claim 5,
Embed the transmitter at a depth below the expected landslide surface,
Marking the ground surface directly above the buried transmitter as the initial position,
Thereafter, the transmitter is periodically started and the detection coil system is moved on the ground surface, so that the center of the detection coil system when the outputs of the first and second phase detection circuits are minimized. Detecting the position as the position directly above the transmitter,
A method for measuring a movement amount and a movement direction by a landslide, wherein a movement amount and a movement direction are measured from a distance and a line segment between the initial position where the marking is performed and the detected position. A method for measuring a lateral movement amount and a movement direction of the seabed ground using the position measurement method according to any one of claims 5 to 7,
The transmitter is buried in the seabed where lateral movement is expected,
Measure the position on the sea level directly above the buried transmitter as the initial position,
Thereafter, the transmitter is periodically activated, and the detection coil system is moved near or at sea level, so that the output of the first and second phase detection circuits is minimized. Detect the center position as the position directly above the transmitter on the sea surface,
A method for measuring a lateral movement amount and a moving direction of a seabed ground, wherein a lateral movement amount and a moving direction are measured from a distance and a line segment between the initial position and the detected position.

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