JP2001141408A - Position measuring method, position indicating method and position measuring device - Google Patents

Abstract

(57) [Summary] [Problem] To quickly and easily calculate the position of an object. SOLUTION: In a position measuring unit LCT, two pairs of magnetic sensors including a magnetic sensor ZMS for detecting a magnetic field in a vertical direction and a magnetic sensor XMS for detecting a magnetic field in a horizontal direction are prepared. Acceleration sensors for detecting the inclination of these magnetic sensors in two orthogonal horizontal directions
XAM and YAM are provided. In addition, an acceleration sensor AAM for detecting the inclination of the coil from the horizontal is provided in the probe PRB, in addition to the coil PCL for generating a magnetic field. The magnetic field generated by the coil PCL is converted into four magnetic sensors XMS-1, XMS-2, ZMS-1, ZMS-2.
The magnitude of these four magnetic fields and the acceleration sensor XA
Using the attitude of the magnetic sensor detected by M and YAM and the inclination of the coil measured by the acceleration sensor AAM in the probe, the relative position of the coil and the magnetic sensor is calculated. A point at which a vertical straight line passing through the coil PCL intersects the ground is indicated by a light beam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position measuring method, a position indicating method, and a position measuring method for detecting a magnetic field generated by an object and calculating the position of the object based on the magnitude of the detected magnetic field. The apparatus is suitable to be applied to a case where an excavation position is measured by a so-called horizontal drilling method.

[0002]

2. Description of the Related Art A horizontal drilling method is known as a method of constructing a pipeline in the ground or on the sea floor without excavation. This horizontal drilling method is a method of drilling a hole in the ground by pushing a drill pipe having a drilling means at the tip by propulsion means, and in order to know the drilling path, the position of the tip of the drill pipe in the ground Need to be measured.

A conventional position measuring method used in the horizontal drilling method will be described with reference to FIGS. FIG. 10 is a diagram for explaining the principle of a conventional position measuring method. In this figure, PRB is a probe, PCL is a coil for generating a magnetic field arranged in the probe PRB, and SRC is a search for detecting a magnetic field. Coil. In the horizontal drilling method, a probe PRB is housed in a drill head, and a magnetic field generated by a coil PCL in the probe PRB is detected by a search coil SRC on the ground to search for the position of the drill head. The measurement is performed by moving the search coil SRC along the surface of the ground and searching for a point where the magnetic field detected by the coil is maximized as shown in FIG. 11, and the drill head (probe PRB) has the maximum magnetic field. Is considered to be directly below the point where

[0004]

In the above-described conventional position measuring method, it takes a long time for the measurement because the measurer needs to move the search coil SRC to find a point where the magnetic field becomes maximum. Become. Further, since it is necessary to perform the movement horizontally and while keeping the direction of the search coil SRC constant, there is a problem that the accuracy of the measurement greatly depends on the skill of the measurer. Further, it is difficult to measure when excavating under a river where a measurer cannot easily enter. In the horizontal drilling method using a small drilling machine, a baseline is drawn on the ground on the planned drilling path in advance, and the following drilling method is used based on the current position of the drill head and the drilling path to the current point. Often it is decided whether to correct the direction. For this purpose, it is convenient if the projection point of the measurement point on the ground is described on the ground.

The present invention has been devised to solve these problems, and an object of the present invention is to provide a position measuring method, a position indicating method, and a position measuring device capable of measuring quickly and easily. It is another object of the present invention to provide a position measuring method and a position measuring device capable of measuring a position where measurement is impossible or difficult with a conventional method. It is another object of the present invention to provide a position indicating method and a position measuring device capable of indicating a projection point of the measured position on the ground.

[0006]

In order to achieve the above object, a position measuring method according to the present invention comprises the steps of: measuring a magnetic field generated from a magnetic field generating coil stored in a probe by a position measuring unit; And a position measuring method for measuring a relative position between the position measuring unit, wherein when the coordinate system fixed to the position measuring unit is a sensor coordinate system, the sensitivity in the x-axis direction of the sensor coordinate system. A first magnetic sensor having a first magnetic sensor and a second magnetic sensor having a sensitivity in the z-axis direction, and four magnetic sensors measured by two magnetic sensor pairs arranged at predetermined intervals in the y-axis direction of the sensor coordinate system. The relative position between the position measurement unit and the probe is calculated based on the magnetic flux density of the position measurement unit, the posture of the position measurement unit, and the inclination angle of the magnetic field generation coil from the horizontal direction. is there.

Further, the position indicating method of the present invention measures a magnetic field generated from a magnetic field generating coil stored in a probe by a position measuring unit to thereby determine a relative position between the probe and the position measuring unit. And a position indicating method for indicating a point where a vertical straight line passes through the probe and intersects the ground surface, and when a coordinate system fixed to the position measuring unit is used as a sensor coordinate system, A pair of two magnetic sensors including a first magnetic sensor having sensitivity in the x-axis direction and a second magnetic sensor having sensitivity in the z-axis direction, and arranged at a predetermined interval in the y-axis direction of the sensor coordinate system. Based on the four magnetic flux densities measured, the posture of the position measuring unit, and the inclination angle of the magnetic field generating coil from the horizontal direction, between the position measuring unit and the probe. Rank Is calculated, based on the calculated output result,
The direction of a parallel ray for passing a point at which a vertical straight line passing through the probe and crossing the ground is calculated.

Further, the position measuring device of the present invention has a position measuring section and a probe, and measures a magnetic field generated from the probe by the position measuring section to thereby establish a position between the probe and the position measuring section. A position measuring device for measuring a relative position, wherein the probe has a first sensor for detecting an inclination angle of the probe axis from a horizontal direction, and the axis is parallel to the probe axis. And a coil driver that supplies an alternating current for generating a magnetic field in the coil, and the position measuring unit uses a rectangular coordinate system fixed to the position measuring unit as a sensor coordinate. A first magnetic sensor having sensitivity in the x-axis direction and a second magnetic sensor having sensitivity in the z-axis direction, and are arranged at predetermined intervals in the y-axis direction of the sensor coordinate system. Sa Two magnetic sensor pairs, second and third sensors for detecting the x-axis component and the y-axis component of the acceleration, and the magnitudes of the four magnetic fields detected by the magnetic sensors. It has a calculating means for calculating a relative position between the position measuring section and the probe from outputs of the first to third sensors.

Further, the probe includes a signal processing means for processing an output of the first sensor to convert the output into a digital signal relating to a tilt angle of the probe, and an AC current supplied to the coil by the coil driver. Modulating means for modulating with a digital signal, the position measuring unit,
There is provided a receiving means for demodulating the digital signal from the received magnetic field and supplying the demodulated digital signal to the calculating means. Alternatively, the probe is the first
Signal processing means for processing the output of the sensor of the present invention and converting the digital signal into a digital signal relating to the inclination angle of the probe; and signal transmitting means for transmitting the digital signal to a signal transmission path. And receiving means for receiving the digital signal transmitted through the computer and supplying the digital signal to the calculating means. Furthermore, the position measurement unit further includes an instruction unit for emitting a light beam, and an angle setting unit for controlling an emission direction of the light beam, and the position measurement unit and the probe calculated by the calculation unit. And controlling the emission direction such that a light beam emitted from the indicating means passes through a point where a vertical straight line passes through the probe and intersects the ground based on a relative position between the two. is there.

[0010]

FIG. 1 is a diagram showing a configuration of an embodiment of a position measuring apparatus to which a position measuring method according to the present invention is applied. In the figure, LCT is a position measurement unit located on the ground, PRB
Is a probe mounted near a drill head in a horizontal drilling method, for example. In the position measurement unit LCT, MSP-1 is a first magnetic sensor pair (magnetic sensor pair 1), M
SP-2 is the second magnetic sensor pair (magnetic sensor pair 2), XMS-1
Is the first x-direction magnetic sensor (x-direction magnetic sensor 1), XM
S-2 is a second x-direction magnetic sensor (x-direction magnetic sensor 2), ZMS-1 is a first z-direction magnetic sensor (z-direction magnetic sensor 1), and ZMS-2 is a second z-direction magnetic sensor ( The z-direction magnetic sensor 2), SLV is a calculation means, XAM is an x-direction acceleration sensor, and YAM is a y-direction acceleration sensor. In the probe PRB, PCL is a coil, DRV is a coil driver, and AAM is an acceleration sensor.

FIG. 2 shows x in the position measuring unit LCT.
Direction magnetic sensor 1XMS-1, x direction magnetic sensor 2XMS-2, z
Direction magnetic sensor 1ZMS-1, z-direction magnetic sensor 2ZMS-2, x
The example of arrangement | positioning of the direction acceleration sensor XAM and the y-direction acceleration sensor YAM is shown. The coordinate axes in the figure are a coordinate system fixed to these components, and in the following description, this coordinate system will be referred to as a local coordinate system. The magnetic sensor pair 1MSP-1 and the magnetic sensor pair 2MSP-2 are the x-direction magnetic sensors 1XMS-1 and z, respectively.
Directional magnetic sensor 2ZMS-2, x-directional magnetic sensor 2XMS-2 and z
The directional magnetic sensor 1ZMS-1 comprises two magnetic sensors. As shown, the x-direction magnetic sensor 1XMS-
1 and the x-direction magnetic sensor 2XMS-2 are arranged to detect a magnetic field in the x-axis direction of the local coordinate system. On the other hand, the z-direction magnetic sensor 1ZMS-1 and the z-direction magnetic sensor 2ZMS-2 are arranged to detect a magnetic field in the z-axis direction of the local coordinate system.
The magnetic sensor pair 1MSP-1 and the magnetic sensor pair 2MSP-2 are arranged on a straight line parallel to the x-axis of the local coordinate system and at an appropriate distance d in the y-axis direction of the local coordinate system. This distance d
Is practically about several tens cm to about 1 m.

The x-direction acceleration sensor XAM is an x-directional accelerometer x
The y-direction acceleration sensor YAM detects the (gravity) acceleration in the axial direction, and the (gravity) in the y-axis direction of the local coordinate system.
It is arranged to detect acceleration. From the outputs of these two acceleration sensors, it is possible to measure the attitude of the magnetic sensor pair 1MSP-1 and the magnetic sensor pair 2MSI-2, that is, the rotation angles about the x axis and the y axis of the local coordinate system. it can. Here, the acceleration sensors XAM and YAM are used to detect the attitude of the magnetic sensor pairs 1 and 2, but any sensor having an equivalent function may be used.

As shown in FIG. 1, the probe PRB comprises:
Includes coil PCL, coil driver DRV, and acceleration sensor AAM. The coil driver DRV functions to supply an alternating excitation current to the coil PCL. Also, it has a function of generating an electric signal of a required frequency, generates an electric signal of a frequency of several tens KHz or less, amplifies and drives the coil PCL. A magnetic field is generated by the alternating current flowing through the coil PCL. This magnetic field can be regarded as a magnetic field due to a magnetic dipole at a place sufficiently distant from the length of the coil. The acceleration sensor AAM detects a tilt angle (tilt angle) of the coil PCL from the horizontal. The coil PCL is usually arranged parallel to the axis of the probe PRB. Also, the probe PRB is usually stored so that its axis is parallel to the axis of the drill head. Although the acceleration sensor AAM is used here to detect the inclination of the coil PCL, any sensor having an equivalent function may be used.

Next, the position measuring method of the present invention using such a probe PRB and the position measuring unit LCT will be described. In the following description, the vertical direction passing through the center of the coil PCL is defined as the z-axis, the horizontal direction included in the plane including the axis of the coil PCL and the z-axis is defined as the x-axis, and the z-axis is orthogonal to the x-axis. A coordinate system in which the axis taken by the right-handed system is the y-axis is called world coordinates and is referred to. The calculating means SLV includes the position measuring unit LCT.
The magnitude of the magnetic field detected by the four magnetic sensors XMS-1, XMS-2, ZMS-1, and ZMS-2, the attitude of the magnetic sensors detected by the two accelerometers XAM and YAM, and the probe PRB From the inclination of the coil PCL detected by the acceleration sensor AAM, the world coordinates of the origin of the local coordinates are calculated. Hereinafter, the calculation method will be described.

A magnetic dipole m located at the origin of the world coordinates and pointing in the x-axis direction is a point r (x, y,
The magnetic flux density vector B created in z) is

(Equation 1) Given by However, the magnetic flux density vector B is represented by local coordinates,

(Equation 2) It is. Here, μ is the magnetic permeability, θ _p is the inclination angle of the coil, and the downward direction is positive. The angles θ _x , θ _y , θ _z are rotation angles of local coordinates with respect to world coordinates.

However, rotation of local coordinates is performed in the following order. First, it is assumed that the local coordinate and the world coordinate are in parallel. First, the local coordinates are rotated by an angle θ _z around the z-axis of the local coordinates (parallel to the z-axis of the world coordinates). The coordinate system after the rotation is referred to as a coordinate system 1. Next, the coordinate system 1 is rotated by an angle θ _y around the y axis of the coordinate system 1. The coordinate system after the second rotation is referred to as a coordinate system 2. Finally, the coordinate system 2 angle theta _x rotation about the x-axis of the coordinate system 2. The coordinate system after rotation will be referred to as a sensor coordinate system again (this coordinate system is rotated together with the magnetic sensor). Note that the above magnetic flux density vector B is expressed using the coordinate system 1.

The coordinates of the origin of the sensor coordinate system expressed in world coordinates are set to r (x, y, z). The distance between the two magnetic sensor pairs is d, and the two magnetic sensor pairs MSP-1 and MSP-2 are (0, + d / 2, 0) and (0, -d /
2,0), the coordinates r ₁ and r ₂ of the magnetic sensor pair MSP-1 and MSP-2 expressed in world coordinates are

(Equation 3) Given by However,

(Equation 4) It is.

By calculating the magnetic flux density of the _two coordinates r ₁ and r ₂ given by the above equation (3) using the above equation (1), the magnetic flux density that should be measured by each sensor is obtained. be able to. As can be understood from the above description of the rotation, the x component and the y component of the magnetic flux density vector expressed in world coordinates are mixed by the rotation, so that the x component of the magnetic flux density vector when viewed in sensor coordinates is used. There is no difference between choosing between the y component and the y component. Therefore, in the present invention, the vertical component and the horizontal component of the magnetic flux density can be measured. Therefore, the measurement is performed such that the z-axis direction of the sensor coordinate system is sufficiently separated from the horizontal, that is, substantially vertical. Therefore, the x-direction magnetic sensor 1XMS-1 and the x-direction magnetic sensor 2XMS-2 can detect a sufficient horizontal magnetic field component.

Here, the size m of the magnetic dipole is measured in advance. Also, the rotation angles θ _x and θ _y and the inclination angle θ _p are
The unknowns are the coordinates (x, y, z) of the origin of the sensor coordinates and the rotation angle θ _z about the z-axis of the sensor coordinates, since the values are obtained by the measurement by the acceleration sensors XAM, YAM and AAM. Therefore, four magnetic sensors XMS-1, XMS-2, Z
The magnetic flux density measured by MS-1, ZMS-2 and x of the magnetic flux density vector B at the position of these magnetic sensors calculated by the above equation
The coordinates (x, y, z) at which the component and the z component are equal and the rotation angle θ _z are obtained. As a method to find this solution, for example, Newton
Method. Thereby, the positional relationship between the origin of the world coordinates (the position of the magnetic dipole) and the origin of the sensor coordinate system can be known.

When the three components of the magnetic flux density measured at two locations using two sets of three-axis magnetic sensors are compared with the calculated values,
In principle, it can be obtained by calculation without measuring any two of the rotation angles θ _x and θ _y and the inclination angle θ _p ,
Since the x component and the y component of the magnetic flux density are handled independently, there is a disadvantage that the accuracy of calculation is reduced. Also, 3
It is possible to use all three components of the magnetic flux density measured at two places using two sets of magnetic sensors of the shaft to minimize the sum of squares of the difference from the calculated value. Calculation accuracy is reduced. Therefore, in the present invention, the above-described method is used.

In the position measuring method of the present invention,
And performs the calculation using a tilt angle theta _p measured by the acceleration sensor AAM stored in the probe PRB. Therefore, it is necessary to transmit the output of the acceleration sensor AAM to the position measurement unit LCT. Figure 3 shows a coil PC with magnetic coupling
FIG. 9 is a block diagram showing a configuration of an embodiment in which a signal related to the inclination of L from the horizontal is transmitted from a probe PRB to a position measurement unit LCT. As is clear from the comparison between FIG. 1 and FIG. 1, in this embodiment, the probe
The signal processing means SPC and the modulation means MOD are added in the PRB, and the receiving means XRC is added in the position measurement unit LCT.

In the probe PRB, the signal processing means SPC processes the output signal of the acceleration sensor AAM, converts it into a digital electric signal, and inputs it to the modulation means MOD. The modulating means MOD functions to modulate a current flowing through the coil PCL by the coil driver DRV. In the present embodiment, the function of generating an electric signal having a frequency of several tens KHz or less as a carrier may be provided in any of the coil driver DRV and the modulating means MOD.
On the other hand, the receiving means XRC includes, for example, a receiving coil,
It is composed of a narrow-band amplifier for signal amplification, a demodulator for extracting a digital signal, and the like, and functions to extract the digital signal transmitted by the magnetic field generated by the coil PCL and deliver it to the calculation means SLV. Here, instead of the receiving coil, the four magnetic sensors XMS-1, XMS-2, ZMS-
1. It is also possible to use any number of one or more of ZMS-2. Calculating means SLV processes the input sent from the reception unit XRC, has a function to be used for position calculation of the inclination angle theta _p coil PCL.

FIG. 4 is a block diagram showing a configuration of an embodiment in which a signal relating to the inclination of the coil PCL from the horizontal is transmitted from the flow PRB to the position measuring unit LCT by a signal transmission path. As shown in this figure, in this embodiment, the modulation means MOD in the embodiment shown in FIG.
And a signal transmission path for transmitting the output of the signal transmission means XMT to the reception means XRC.
TXL is provided. The signal transmission means XMT transmits the digital electric signal generated by processing the signal of the acceleration sensor AAM by the signal processing means SPC to the signal transmission line TXL as it is in the baseband or by mounting it on an appropriate carrier. The receiving means XRC in the position measurement unit LCT, in the present embodiment,
It is composed of a narrow band amplifier for signal amplification, a demodulator for extracting a digital signal, and the like, and has a function of extracting the digital signal transmitted through the signal transmission line XMT and delivering it to the calculation means. Calculating means SLV processes the input sent from the reception unit XRC, has a function to be used for position calculation of the inclination angle theta _p coil PCL.

Next, a description will be given of a position indicating method and a position measuring apparatus according to the present invention for indicating a projection point on the ground surface of the position of the probe measured by the above-described position measuring method.
FIG. 5 is a block diagram showing a configuration of a position measuring apparatus in which a position indicating function according to the position indicating method of the present invention is added to the embodiment shown in FIG. 6 shows the configuration of an embodiment in which the position indicating function is added to the position measuring device shown in FIG. 3, and FIG. 7 shows the position measuring device shown in FIG. 1 shows a configuration of an embodiment to which functions are added. As is clear from comparison between FIGS. 5 and 1, FIGS. 6 and 3, and FIGS. 7 and 4, in FIGS. 5, 6 and 7, the support S is provided in the position measuring unit LCT.
PT, angle setting means GMT, and instruction means LPT are provided.

FIG. 8 is a diagram showing an example of the arrangement of each component in the position measuring unit LCT. As shown in FIG.
SPT is magnetic sensor pair 1MSP-1, magnetic sensor pair 2MSP-2,
It supports the x-direction acceleration sensor XAM, the y-direction acceleration sensor YAM, the indicating means LPT, and the angle setting means GMT, and functions to maintain the mutual position and angle. The pointing hand LPT is composed of a light source and an optical system for converting the light emitted from the light source into parallel rays, and irradiates and points a point where a vertical straight line passing through the coil PCL (probe PRB) and the ground intersects with the ground. belongs to. As the instructing means LPT, for example, a laser pointer is used. The angle setting means GMT has a function of setting the angle of the pointing means LPT in a predetermined direction so that the pointing means LPT can irradiate the irradiation point. The control for setting the angle may be performed by the angle setting means GMT, or may be performed by the calculation means SLV. However, the calculating means SLV has a function of controlling the angle setting means GMT in the latter case, and is necessary for calculating the angle to be set or the angle to be set by the angle setting means GMT in the former case. It is necessary to have a function to give information to the angle setting manual throw GMT.

An example of a method of calculating an angle to be set by the angle setting means GMT will be described below. Pointer LP
T is the rotation center when is set the angle by the angle setting means GMT, the instruction unit LPT is the optical axis of the parallel light rays to be emitted, coordinates r _p (x _p of the rotation center, y _p, z _p ). Also, assuming that the coordinate of the origin of the world coordinates (center of the coil PCL) represented by the sensor coordinates is r _L , r _L is

(Equation 5) Given by

Next, the unit vector v _{L in} the z-axis direction of world coordinates is

(Equation 6) The sensor coordinate r _T that gives the point where the world z-axis intersects the ground is given by

(Equation 7) Becomes However, it is assumed that the z-plane of the sensor coordinates is parallel to the ground.

Therefore, the vector a representing the direction to be set is:

(Equation 8) Given by In the direction of this vector, the pointing means LPT
, A target point can be indicated as long as the z-plane of the sensor coordinates is parallel to the ground.
FIG. 9 shows this state.

[0029]

As described above, according to the position measuring method and apparatus of the present invention, it is not necessary to search for the point where the magnetic field generated by the underground coil becomes maximum. Thus, the position of the drill head can be measured quickly. Further, position measurement in a place where measurement is impossible or difficult with the conventional method can be easily performed. Furthermore, according to the position indicating method and the position measuring device of the present invention, it is possible to indicate the projected point of the measured position on the ground, and it is possible to easily draw the projected point of the path of the excavation hole on the ground. .

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a basic embodiment of the present invention.

FIG. 2 is a diagram showing an example of the arrangement of a magnetic sensor and an acceleration sensor according to the present invention.

FIG. 3 is a diagram showing a configuration of an embodiment of the present invention in which a tilt angle is transmitted by a magnetic field.

FIG. 4 is a diagram showing a configuration of an embodiment of the present invention in which transmission of an inclination angle is performed by a signal transmission path.

FIG. 5 is a diagram showing a configuration of an embodiment for indicating a measured position.

FIG. 6 is a diagram showing a configuration of another embodiment for indicating a measured position.

FIG. 7 is a diagram showing a configuration of still another embodiment for indicating a measured position.

FIG. 8 is a diagram for explaining the arrangement of an instruction unit, an angle setting unit, and an acceleration sensor.

FIG. 9 is a diagram for explaining the operation of the instruction means.

FIG. 10 is a principle diagram of a conventional position measurement method.

FIG. 11 is an explanatory diagram of a conventional measurement method.

[Explanation of symbols]

 AAM Acceleration sensor DRV Coil driver GMT Angle setting means LCT Position measurement unit LPT indication means MSP-1, MSP-2 Magnetic sensor pair 1 and 2 MOD Modulation means PCL coil PRB Probe SLV calculation means SPC signal processing means SPT support SRC search coil TXL signal transmission path XAM x direction acceleration sensor XMS-1, XMS-2 x direction magnetic sensor 1 and 2 YAM y direction acceleration sensor ZMS-1, ZMS-2 z direction magnetic sensor 1 and 2 XRC receiving means XMT transmitting means

Claims (6)

[Claims] 1. A position measuring method for measuring a relative position between the probe and the position measuring unit by measuring a magnetic field generated from a magnetic field generating coil stored in the probe by a position measuring unit. When the coordinate system fixed to the position measuring unit is a sensor coordinate system, the first magnetic sensor having sensitivity in the x-axis direction and the second magnetic sensor having sensitivity in the z-axis direction of the sensor coordinate system include: And four magnetic flux densities measured by two magnetic sensor pairs arranged at a predetermined interval in the y-axis direction of the sensor coordinate system, the attitude of the position measuring unit, and the horizontal direction of the magnetic field generating coil. A position measuring method, wherein a relative position between the position measuring unit and the probe is calculated based on a tilt angle from a direction. 2. A relative position between the probe and the position measuring unit is measured by measuring a magnetic field generated from a magnetic field generating coil stored in the probe by a position measuring unit. A method for designating a point at which a vertical straight line intersects the ground surface, wherein a coordinate system fixed to the position measuring unit is a sensor coordinate system, and a second coordinate system having sensitivity in the x-axis direction of the sensor coordinate system. Four magnetic fluxes measured by two magnetic sensor pairs, each of which is composed of one magnetic sensor and a second magnetic sensor having sensitivity in the z-axis direction, and are arranged at predetermined intervals in the y-axis direction of the sensor coordinate system. Calculating a relative position between the position measuring unit and the probe based on a density, an orientation of the position measuring unit, and an inclination angle of the magnetic field generating coil from a horizontal direction, Based on Te, position indicating method characterized by calculating the direction of the parallel rays to as vertical straight line the probe passes through the point of intersection with the ground. 3. A position having a position measuring unit and a probe, and measuring a magnetic field generated from the probe by the position measuring unit to measure a relative position between the probe and the position measuring unit. A measurement device, wherein the probe has a first sensor for detecting an inclination angle of the axis of the probe from a horizontal direction, and a coil arranged such that the axis is parallel to the axis of the probe, A coil driver that supplies an alternating current for generating a magnetic field in the coil, wherein the position measuring unit has an x-axis when a rectangular coordinate system fixed to the position measuring unit is used as a sensor coordinate system. Two magnetic sensor pairs each comprising a first magnetic sensor having sensitivity in the direction and a second magnetic sensor having sensitivity in the z-axis direction and arranged at a predetermined interval in the y-axis direction of the sensor coordinate system. And Second and third sensors for detecting the x-axis component and the y-axis component of the degree, and the magnitudes of the four magnetic fields detected by the magnetic sensor and the outputs of the first to third sensors. And a calculating means for calculating a relative position between the position measuring unit and the probe. 4. The signal processing means for processing the output of the first sensor to convert the output of the first sensor into a digital signal relating to the tilt angle of the probe, and the AC current supplied to the coil by the coil driver. And a modulating means for modulating the digital signal with a signal, wherein the position measuring unit demodulates the digital signal from a received magnetic field, and includes a receiving means for supplying the demodulated digital signal to the calculating means. Item 3
The position measuring device as described. 5. The probe has signal processing means for processing an output of the first sensor to convert the output into a digital signal related to the tilt angle of the probe, and signal transmitting means for transmitting the digital signal to a signal transmission path. 4. The position measuring device according to claim 3, wherein the position measuring unit includes a receiving unit that receives the digital signal transmitted through the signal transmission path and supplies the digital signal to the calculating unit. 6. The position measurement unit further includes an instruction unit for emitting a light beam, and an angle setting unit for controlling an emission direction of the light beam, and the position measurement unit and the probe calculated by the calculation unit. And controlling the emission direction such that a ray emitted from the indicating means passes through a point where a vertical straight line passes through the probe and intersects the ground based on the relative position between 4. The method according to claim 3, wherein
The position measuring device according to any one of claims 1 to 5.