JPH08146146A - Position detecting method - Google Patents

Abstract

PURPOSE: To accurately and efficiently detect the direction where a detecting object is positioned from an optional position without being influenced by an obstacle and without requiring a great deal of time and labor. CONSTITUTION: Intensity of a magnetic field generated by a magnetic field generating means arranged on a detecting object is measured by magnetism detecting elements arranged at observation points, and the position of the detecting object is detected from these magnetic field intensity measured values. Plural magnetism detecting elements 14 and 15 whose magnetism detecting surfaces are aligned and arranged on the same plane are used. The arranging attitude of the magnetic field generating means 6 and the magnetism detecting elements 14 and 15 is adjusted so that both magnetic field intensity measured values detected by the plural magnetism detecting elements 14 and 15 become a minimum value. The position of the detecting object 1 is detected from the direction shown by the aligning direction of the magnetism detecting elements 14 and 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting method for detecting the position of various detected objects such as detecting the position of an underground buried object such as a buried pipe from the ground surface in the field of civil engineering, and especially to measure the magnetic field strength. System position detection method.

[0002]

2. Description of the Related Art As a position detecting method for detecting the position of an underground buried object such as a buried pipe from the ground surface, the strength of a magnetic field generated by a magnetic field generating means arranged on a detected object such as an underground buried object The position detection method of the magnetic field strength measurement method is already known, which is measured by the magnetic detection element arranged at the observation point, and the position of the detected object is detected from this magnetic field strength measurement value.
This is disclosed in JP-A-57-133373 and JP-A-59-59.
It is disclosed in Japanese Patent No. 153112.

In the position detecting method disclosed in Japanese Patent Laid-Open No. 57-133373, the magnetic field generating means is attached to the object to be detected so that the central magnetic field lines are in the vertical direction, and the magnetic field generated by the magnetic field generating means is perpendicular to the detected object. The component is scanned and measured by a magnetic detection element having a horizontally arranged magnetic detection surface, and the position of the detected object is detected from the center position of a circle drawn by the locus of the point where the measured value shows the minimum value.

In the position detecting method disclosed in Japanese Patent Laid-Open No. 59-153112, a magnetic field generating means is attached to the object to be detected so that the central magnetic force line is in the vertical direction, and the interlinking surface (magnetic detecting surface) is vertical. The magnetic detection element is reciprocally moved in a direction passing through the interlinking surface at a right angle, and the position of the detected object is detected from the position where the magnetic field strength measured by the magnetic detection element shows the minimum value during this movement process. .

[0005]

Problems to be Solved by the Invention JP-A-57-1333
In the position detection method disclosed in Japanese Patent Publication No. 73, the magnetic field strength must be measured many times by changing the measurement position so that the point where the measurement value is the minimum value draws a circle. It takes a lot of time and labor to detect the position of an object, and if an obstacle such as a tree, a card rail, or a power pole exists on the ground, the position of the detected object may not be detected.

In the position detecting method disclosed in Japanese Patent Laid-Open No. 59-153112, the relative positional relationship of the interlinking surface of the magnetic detecting element with respect to the direction of the central magnetic force line of the magnetic field generated by the magnetic field generating means, the magnetic detecting element If the moving direction and the like are not set accurately, accurate position detection may not be performed, and measurement may be performed without these conditions being met, resulting in erroneous detection.

If an obstacle exists on the ground directly above the object to be detected, the position of the object to be detected cannot be detected and only the position directly above the object to be detected can be detected. It cannot detect the direction to go. For this reason, for example, in the burial construction of an underground burial pipe, in the case where a branch pipe is connected to the main sewer pipe without digging, it is not possible to determine in which direction the construction start position should be excavated.

The present invention has been made by paying attention to the above-mentioned problems, and the direction in which a detected object is located from an arbitrary position without being affected by an obstacle is accurately, and it takes a long time. It is an object of the present invention to provide a position detection method of a magnetic field strength measurement method that enables efficient and efficient detection without requiring labor.

[0009]

In order to achieve the above object, in the position detecting method according to claim 1, the intensity of the magnetic field generated by the magnetic field generating means arranged on the object to be detected is arranged at the observation point. In a position detection method of measuring with a magnetic detection element and detecting the position of the detected object from the magnetic field strength measurement value, a plurality of magnetic detection elements whose magnetic detection surfaces are aligned on the same plane are used. The arrangement postures of the magnetic field generating means and the magnetic detection element are adjusted so that the magnetic field strength measurement values detected by the individual magnetic detection elements are both minimum values, and It is characterized by detecting the position of an object to be detected.

In order to achieve the above-mentioned object, the position detecting method according to claim 2 supplies an electric signal to the magnetic field generating means arranged on the object to be detected, and observes the magnetic field generated by the magnetic field generating means. Is a position detection method for detecting the position of the object to be detected from the output signal of the magnetic detection element, which is detected by a magnetic detection element arranged in The magnetic field generation means and the magnetic detection element are used so that the phases of the output signals output from the plurality of magnetic detection elements are inverted at the same time with respect to the phase of the electric signal supplied to the magnetic field generation means. Is adjusted to detect the position of the detected object from the direction indicated by the alignment direction of the magnetic detection elements.

[0011]

In the position detecting method according to claim 1, when the magnetic field strength measurement values of the plurality of magnetic detection elements are both minimized by adjusting the arrangement postures of the magnetic field generation means and the magnetic detection element, the magnetic field generation means is activated. The magnetic detection surface of the magnetic detection element is aligned with the same plane as the plane including the central magnetic force line of the generated magnetic field. Accordingly, at this time, the direction indicated by the alignment direction of the magnetic detection elements points to the position of the detected object, and the position of the detected object, particularly the direction in which the detected object is located from the observation point, is detected.

In the position detecting method according to the second aspect, when the magnetic detecting surface of the magnetic detecting element is aligned with the same plane as the plane including the central magnetic force line of the magnetic field generated by the magnetic field generating means, the output signal output from the magnetic detecting element is changed. Utilizing the fact that the phase is inverted at the same time with respect to the phase of the electric signal supplied to the magnetic field generating means, a plurality of magnetic detecting elements output by adjusting the arrangement postures of the magnetic field generating means and the magnetic detecting element. When the phase of the output signal is simultaneously inverted with respect to the phase of the current supplied to the magnetic field generation means, the direction indicated by the alignment direction of the magnetic detection elements indicates the position of the detected object, and the position of the detected object, In particular, the direction in which the detected object is located is detected from the observation point.

The term "inversion of the phase" as used herein means that the phase of the output signal output from the magnetic detection element is the same as the phase of the electric signal supplied to the magnetic field generating means.
It means that an 80 degree phase difference is generated or vice versa.

[0014]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of a position detecting device used in an embodiment of the position detecting method according to claim 1. In FIG. 1, reference numeral 1 indicates a detected buried pipe buried in the ground, and a movable carriage 2 is inserted into the detected buried pipe 1. A wheel rotation amount sensor (not shown) such as a rotary encoder is connected to the wheels 3 of the movable carriage 2, and a signal output from this wheel rotation amount sensor is transmitted to the control device 5 through a signal line 4.

The control device 5 measures the moving distance of the moving carriage 2 in the detected buried pipe 1 by a signal from the wheel rotation amount sensor. A transmission coil 6 as a magnetism generating means is attached to the movable carriage 2 by a posture control means 7 so as to be rotationally displaceable around the same axis as the central axis X of the detected buried pipe 1. The transmission coil 6 receives an AC voltage from the signal supply device 8 such as an oscillator through the power line 9, and generates a magnetic field in which the central magnetic force line Mc extends in the direction orthogonal to the central axis X at any rotational displacement position.

The magnetic detection device 10 is movably arranged at an observation point on the ground. The magnetic detection device 10 is capable of being rotationally displaced about an axis parallel to the central axis X of the buried pipe 1 to be detected by the base 11 and the moving means 12 on the base 11, and in a direction that penetrates the plate surface thereof at a right angle. And a substrate 13 movably provided in parallel therewith. The substrate 13 has a lower receiving coil 14 and an upper receiving coil 1 as magnetic detection elements.
5 and each magnetic detection surface 14a, 15a on the same plane,
In this case, they are vertically aligned and fixed in a mode in which they are arranged on one plane parallel to the plate surface of the substrate 13.

Lower receiving coil 14 and upper receiving coil 15
Respectively measure the magnetic field strength, and the measurement signal is the signal line 16,
It is transmitted by 17 to measuring instruments 18, 19. Measuring instrument 1
Reference numerals 8 and 19 respectively have magnetic field strength meters 20 and 21, and the magnetic fields measured by the lower receiving coil 14 and the upper receiving coil 15 by the measurement signals input from the lower receiving coil 14 and the upper receiving coil 15, respectively. Magnetic field strength meter 2
Displayed by 0 and 21. When detecting the position, the magnetic detection surfaces 14 of the lower receiving coil 14 and the upper receiving coil 15 are detected.
a, 15a through the center of each of the magnetic detection surfaces 14a, 1a
The movable carriage 2 is moved so that the center of the transmission coil 6 is located at the intersection of the plane orthogonal to 5a and the central axis X of the detected buried pipe 1.

In this state, as shown in FIG. 2, the direction of the central magnetic force line Mc of the transmission coil 6 and the magnetic detection surfaces 14a, 1a of the lower receiving coil 14 and the upper receiving coil 15, respectively.
The extension direction of 5a is the same, in other words, the magnetic field emission surface 6a of the transmission coil 6 and the magnetic detection surfaces 14a and 15a are not orthogonal to each other, and the lower receiving coil 14 and the upper receiving coil 15 are mounted on the substrate. When the plate surface is perpendicularly penetrated by 13, ie, translated in a direction indicated by an arrow A in FIG. 2, the central magnetic field line Mc of the transmitter coil 6 and the lower receiving coil 6 as shown in FIG. 14, upper receiving coil 1
The minimum value of the magnetic field strength measured by the lower receiving coil 14 and the upper receiving coil 15 according to the angle formed by the magnetic detection surfaces 14a and 15a of 5 is the actual central position of the transmitting coil 6 (the position of the central magnetic force line Mc). It appears at a position further deviated, and the measurement position of the minimum value appears at different positions in the lower receiving coil 14 and the upper receiving coil 15.

Here, the measured values of the lower side receiving coil 14 and the upper side receiving coil 15 can take the minimum value at the same time because the lower side receiving coil 14 on the central magnetic force line Mc of the transmitting coil 6,
This is a case where the magnetic detection surfaces 14a and 15a of the upper receiving coil 15 are located, and at this time, the magnetic field line emission surface 6a of the transmission coil 6 and the magnetic detection surfaces 14a and 15a are orthogonal to each other.

Next, a procedure for implementing the position detecting method according to the present invention will be described with reference to FIGS. FIG. 4 shows an implementation procedure of the position detecting method according to the present invention. First, the transmitting coil 6 is rotationally displaced around the central axis X of the detected buried pipe 1 by the attitude control means 7 (step 10), and the lower receiving coil is obtained. The rotational displacement position where the magnetic field strength measured by 14 is minimized is found (step 20), and the rotational displacement of the transmission coil 6 is stopped at that rotational displacement position (step 3).
0).

As a result, as shown in FIG. 5A, the magnetic fields of the lower receiving coil 14 and the upper receiving coil 15 are arranged in a plane parallel to the plane containing the central magnetic force line Mc of the magnetic field generated by the transmitting coil 6. The detection surfaces 14a and 15a are aligned, and the magnetic field line emission surface 6a of the transmission coil 6 and the magnetic detection surfaces 14a and 15
It is orthogonal to a. In addition, the mutual attitude adjustment of the transmission coil 6, the lower receiving coil 14, and the upper receiving coil 15 is performed by
The lower receiving coil 1 together with the substrate 14 by the moving means 12
4. The upper receiving coil 15 may be rotationally displaced.

Next, it is judged whether the measured value of the magnetic field strength by the upper receiving coil 15 is the minimum value (step 40). If it is not the minimum value, the moving means 12 moves the substrate 14 together with the lower receiving coil 14 and the upper receiving coil. 15 is translated (step 50), the displacement direction is determined based on the behavior of the magnetic field strength measurement value by the upper receiving coil 15, and the parallel movement direction is selected and set (step 60). The position where the minimum value is obtained is found, and the parallel movement of the lower receiving coil 14 and the upper receiving coil 15 is stopped at that parallel moving position (step 70).

Next, it is confirmed whether or not the measured values of the magnetic field strengths of the lower receiving coil 14 and the upper receiving coil 15 are both minimum values (step 80), and the magnetic field strengths of the lower receiving coil 14 and the upper receiving coil 15 are checked. If neither of the measured values is the minimum value, the process returns to step 10 and the attitudes of the transmitting coil 6, the lower receiving coil 14, and the upper receiving coil 15 are adjusted again.

Lower receiving coil 14 and upper receiving coil 15
When the measured values of the magnetic field strength of both become the minimum values, FIG.
, The central magnetic field line Mc of the transmission coil 6 is
The magnetic detection surfaces 14a and 15a of the lower receiving coil 14 and the upper receiving coil 15 are located above. In this state, the alignment direction of the lower receiving coil 14 and the upper receiving coil 15 indicates the pipe center of the detected buried pipe 1, which allows the detected buried pipe 1 to be positioned from any observation point on the ground. The direction to do is detected.

FIG. 6 shows an embodiment of the position detecting device used in the embodiment of the position detecting method according to claim 2.
Incidentally, in FIG. 6, the portions corresponding to those in FIG. 1 are designated by the same reference numerals as those in FIG. In this embodiment, the magnetic lines of force generated by the transmission coil 6 enter from the front side of the magnetic detection surfaces of the lower and upper reception coils 14 and 15, and enter the magnetic detection surface from a direction orthogonal to the magnetic detection surfaces. When entering from the back side of the surface, the phase of the output signals output from the lower and upper receiving coils 14 and 15 with respect to the electric signal supplied to the transmitting coil 6 changes, and the magnetic lines of force generated by the transmitting coil 6 become lower and When entering from the front side of the magnetic detection surface of the upper receiving coils 14 and 15, the magnetic lines of force generated by the transmitting coil 6 are lower and upper receiving coils 1.
The fact that the phases of the output signals of the lower and upper receiving coils 14 and 15 with respect to the electric signals are inverted when the case is entered from the back side of the magnetic detection surfaces of 4 and 15 is used.

Therefore, in this embodiment, the measuring devices 18, 1
Reference numerals 9 each have a reference signal of the same phase as the AC voltage supplied to the transmission coil 6 input from the signal supply device 8 through the signal transmission cable 20, and the lower reception coil 14 and the upper reception coil 1
By the synchronous detection of each output voltage of 5 and the reference signal, the phase shift direction of the output voltage with respect to the AC voltage supplied to the transmission coil 6 is detected, and these are displayed on the screen display units 21 and 22.

In this case, if the phase of the output voltage output from the lower receiving coil 14 and the upper receiving coil 15 is the same as the phase of the AC voltage supplied to the transmitting coil 6 due to the synchronous detection, the half in the plus direction. When a wave is obtained, the phase of the output voltage output from the lower receiving coil 14 and the upper receiving coil 15 has a phase difference of 180 degrees with respect to the phase of the AC voltage supplied to the transmitting coil 6. A half-wave in the negative direction is obtained in the negative direction, and the phase of the output voltage of the lower receiving coil 14 and the upper receiving coil 15 is inverted with respect to the phase of the AC voltage supplied to the transmitting coil 6 by determining the polarity of this half-wave. Can be detected. When detecting the position, the magnetic detection surfaces 14a, 15 of the lower receiving coil 14 and the upper receiving coil 15 are detected.
At the intersection of the plane perpendicular to the magnetic detection surfaces 14a and 15a passing through the centers of a and the central axis X of the detected buried pipe 1,
The moving carriage 2 is moved so that the center of the transmitting coil 6 is located.

In this state, as shown in FIG. 2, the direction of the central magnetic force line Mc of the transmitting coil 6 and the magnetic detection surfaces 14a, 1a of the lower receiving coil 14 and the upper receiving coil 15 are shown.
The extension direction of 5a is the same, in other words, the magnetic field emission surface 6a of the transmission coil 6 and the magnetic detection surfaces 14a and 15a are not orthogonal to each other, and the lower receiving coil 14 and the upper receiving coil 15 are mounted on the substrate. When the plate surface is perpendicularly penetrated by 13, ie, translated in a direction indicated by an arrow A in FIG. 2, the central magnetic force line Mc of the transmission coil 6 and the magnetic detection surfaces of the lower receiving coil 14 and the upper receiving coil 15 are moved. 14a, 15
As shown in FIGS. 7 (a) and 7 (b), the phase of the output voltage of the lower receiving coil 14 and the upper receiving coil 15 is an alternating current supplied to the transmitting coil 6 in accordance with the angle formed by a. The position appears with respect to the voltage phase at a position deviated from the actual center position of the transmission coil 6 (position of the center magnetic force line Mc),
This position also appears at different positions in the lower receiving coil 14 and the upper receiving coil 15 depending on the distance between the lower receiving coil 14 and the upper receiving coil 15.

Here, the fact that the phases of the output voltages of the lower receiving coil 14 and the upper receiving coil 15 are inverted at the same time with respect to the phase of the AC voltage supplied to the transmitting coil 6 is on the central magnetic field line Mc of the transmitting coil 6. This is the case where the magnetic detection surfaces 14a and 15a of the lower receiving coil 14 and the upper receiving coil 15 are located at the position of the magnetic field line emitting surface 6a of the transmitting coil 6, respectively.
And the magnetic detection surfaces 14a and 15a are orthogonal to each other.

Next, a procedure for implementing the position detecting method according to the present invention will be described with reference to FIGS. 8 and 5. FIG. 8 shows an implementation procedure of the position detecting method according to the present invention. First, the transmitter coil 6 and the lower part are arranged below the phase shift direction of the output voltage displayed on the screen display portions 21 and 22 of the measuring instruments 18 and 19. The direction of deviation from the side and upper receiving coils 14 and 15 is determined (step 10), and the transmitting coil 6 is rotationally displaced about the central axis X of the detected buried pipe 1 by the attitude control means 7 (step 20).

Under this rotational displacement, a rotational displacement position where the phase of the output voltage output from the lower receiving coil 14 is inverted with respect to the phase of the AC voltage supplied to the transmitting coil 6 is found (step 20), and the rotational displacement is determined. Transmit coil 6 at position
The rotational displacement of is stopped (step 40). This allows
As shown in FIG. 5A, the magnetic detection surfaces 1 of the lower receiving coil 14 and the upper receiving coil 15 are arranged on a plane parallel to the plane including the central magnetic force line Mc of the magnetic field generated by the transmitting coil 6.
4a and 15a are aligned and the magnetic field line emitting surface 6 of the transmitting coil 6
a and the magnetic detection surfaces 14a and 15a are orthogonal to each other.

The mutual attitude adjustment of the transmitting coil 6, the lower receiving coil 14 and the upper receiving coil 15 is carried out by the moving means 12 together with the substrate 14 together with the lower receiving coil 14.
The upper receiving coil 15 may be rotationally displaced. Next, it is judged whether or not the phase of the output voltage of the upper receiving coil 15 is inverted with respect to the phase of the AC voltage supplied to the transmitting coil 6 (step 50). , 19 of the screen display units 21 and 22 are discriminated from the phase shift direction of the output voltage on the screen, the shift directions of the transmission coil 6 and the lower and upper reception coils 14 and 15 are determined (step 60). The lower receiving coil 14 and the upper receiving coil 1 are moved together with the substrate 14 by the moving means 12.
5 is translated (step 70), and the upper receiving coil 1
A position where the phase of the output voltage of 5 is inverted with respect to the phase of the AC voltage supplied to the transmitting coil 6 is found, and the parallel movement of the lower receiving coil 14 and the upper receiving coil 15 is stopped at the parallel movement position (step 80).

Next, it is confirmed that the phases of the output voltages of the lower receiving coil 14 and the upper receiving coil 15 are both inverted with respect to the phase of the AC voltage supplied to the transmitting coil 6 (step 90). 14 and upper receiving coil 1
If the phase of the output voltage of 5 is not inverted with respect to the phase of the AC voltage supplied to the transmitting coil 6, the process returns to step 10 and the transmitting coil 6 and the lower receiving coil 14 and the upper receiving coil 15 are separated. Repeat the mutual posture adjustment. When the phases of the output voltages of the lower receiving coil 14 and the upper receiving coil 15 are both inverted with respect to the phase of the AC voltage supplied to the transmitting coil 6, as shown in FIG. The magnetic detection surfaces 14a and 15a of the lower receiving coil 14 and the upper receiving coil 15 are located on the central magnetic force line Mc.

In this state, the lower receiving coil 14
The direction in which the upper receiving coil 15 and the upper receiving coil 15 are aligned indicates the pipe center of the detected buried pipe 1, and the direction in which the detected buried pipe 1 is located is detected from an arbitrary observation point on the ground.
In the above-described embodiment, the phase inversion is determined by the phase of the output voltage of the lower receiving coil 14 and the upper receiving coil 15 and the phase of the AC voltage supplied to the transmitting coil 6. You may perform with the electric current which deviated. The position detection method according to the present invention is not limited to the position detection of the underground buried pipe, and may be used for position detection of various other objects to be detected.

[0035]

As can be understood from the above description, according to the position detecting method of the present invention, the direction in which a detected object is located from an arbitrary observation point can be greatly improved with good work efficiency regardless of the presence or absence of obstacles. It is possible to detect accurately without requiring a lot of time and labor. Therefore, for example, when burying an underground buried pipe, when connecting a branch pipe to the sewer main without digging, it is possible to accurately determine which direction to excavate from the construction start position. Easy,
Can be determined quickly and accurately.

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing an embodiment of a position detection device used for carrying out a position detection method according to the present invention.

FIG. 2 is an explanatory view showing a state in which a magnetic field line emitting surface of a transmitting coil and a magnetic detecting surface of a receiving coil are not orthogonal to each other.

FIG. 3 is a graph showing the relationship between the magnetic field intensity measurement values of the lower receiving coil and the upper receiving coil and the position of the receiving coil when the magnetic field radiation surface of the transmitting coil and the magnetic detecting surface of the receiving coil are not orthogonal to each other.

FIG. 4 is a flowchart showing a procedure for implementing a position detection method according to the present invention.

5 (a) and 5 (b) are explanatory views showing a state in which the magnetic field line emission surface of the transmission coil and the magnetic detection surface of the reception coil are orthogonal to each other.

FIG. 6 is a system configuration diagram showing an embodiment of a position detection device used for implementing the position detection method according to the present invention.

7 (a) and 7 (b) are phase inversion positions of output voltages of the lower receiving coil and the upper receiving coil, respectively, in a state in which the magnetic field line emitting surface of the transmitting coil and the magnetic detecting surface of the receiving coil are not orthogonal to each other. The graph which shows the relationship with the position of a receiving coil.

FIG. 8 is a flowchart showing a procedure for carrying out the position detection method according to the present invention.

[Explanation of symbols]

 1 ... Detecting buried pipe 2 ... Mobile trolley 3 ... Wheel 4 ... Signal line 5 ... Control device 6 ... Transmitting coil 7 ... Posture control means 8 ... Signal supply device 9 ... Power line 10 ... Magnetic detection device 11 ... Base 12 ... Moving Means 13 ... Substrate 14 ... Lower receiving coil 15 ... Upper receiving coil 16, 17 ... Signal line 18, 19 ... Measuring instrument 20, 21 ... Magnetic field strength meter

Claims (2)

[Claims] 1. The strength of a magnetic field generated by a magnetic field generating means arranged on an object to be detected is measured by a magnetic detection element arranged at an observation point, and the position of the object to be detected is detected from the measured value of the magnetic field strength. In the position detection method, a plurality of magnetic detection elements whose magnetic detection surfaces are aligned on the same plane are used, and the magnetic field strength measurement values detected by the plurality of magnetic detection elements are both minimized. A position detecting method characterized in that the positions of the magnetic field generating means and the magnetic detection elements are adjusted and the position of the detected object is detected from the direction indicated by the alignment direction of the magnetic detection elements. 2. An electric signal is supplied to a magnetic field generating means arranged on an object to be detected, a magnetic field generated by the magnetic field generating means is detected by a magnetic detecting element arranged at an observation point, and an output of the magnetic detecting element. A position detection method for detecting the position of the object to be detected from a signal, wherein a plurality of magnetic detection elements having magnetic detection surfaces aligned on the same plane are used, and an output output from the plurality of magnetic detection elements. The arrangement postures of the magnetic field generation means and the magnetic detection element are adjusted so that the phase of the signal is inverted at the same time with respect to the electric signal supplied to the magnetic field generation means, A position detection method characterized by detecting the position of an object to be detected.