Measurement device, measurement method, measurement program, and recording medium

Abstract

To accurately measure an attitude of an excavation part during excavation.SOLUTION: A measurement device according to the present invention comprises an attitude estimation unit and a phase correction amount calculation unit. The phase correction amount calculation unit finds an offset from a gravitational force tool face and a magnetic force tool face and adopts the same as an estimate offset. The attitude estimation unit adopts the gravitational force tool face based on acceleration data as a measurement gravitational force tool face, the magnetic tool face based on magnetic field data as a measurement magnetic force tool face, a difference in offset and estimate offset between the measurement gravitational force tool face and the measurement magnetic force tool face as a phase correction amount, and the data corrected from magnetic field data by the phase correction amount as magnetic field data after correction, respectively, and finds an attitude based on the acceleration data and the magnetic field data after correction.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a measurement device, a measurement method, a measurement program, and a recording medium for determining an attitude using outputs from an acceleration sensor and a magnetic sensor arranged in an excavation section of an underground excavator. [Background technology]

[0002] The technology shown in Patent Document 1 is known as a conventional technology. Patent Document 1 uses two sensor sets and shows that measurement data is calibrated or corrected. Figure 1 shows an example of the correction operation process shown in Figure 4 of Patent Document 1. Non-Patent Document 1 shows that eddy currents are generated in conductors that shield alternating magnetic fields. Patent Document 1 also points out that eddy currents are generated in conductors present in the excavation section due to the influence of the earth's magnetic field during excavation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Publication No. 2019 / 0353023 [Non-patent literature]

[0004] [Non-Patent Document 1] Takuro Ando, ​​Tsuneyoshi Takasuna, "Metal Enclosed Bus and Its Analysis", Hitachi Review, Vol. 39, No. 6, pp. 11-16, June 1957. Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 introduces various techniques for cases where data from a sensor set has been corrupted. However, Patent Document 1 does not clearly state a method for accurately measuring the posture of an excavation part during excavation. In recent years, there has been a demand for measuring the posture even during excavation to improve efficiency, but the problem with measurements during excavation is that there is a large error. The present invention aims to provide a technique for accurately measuring the posture of an excavation part during excavation. [Means for solving the problem]

[0006] The measuring device of the present invention determines the attitude using acceleration data output from at least a three-axis acceleration sensor and magnetic field data output from at least a three-axis magnetic sensor arranged in the excavation section of an underground excavator. The measuring device of the present invention includes a processor. The processor has an attitude estimation section and a phase correction amount calculation section. The attitude estimation section determines the attitude of the excavation section based on the acceleration data and the magnetic field data. The phase correction amount calculation section determines the offset between the gravity tool face and the magnetic tool face as an estimated offset. More specifically, the attitude estimation section determines the gravity tool face based on the acceleration data as the measured gravity tool face, the magnetic tool face based on the magnetic field data as the measured magnetic tool face, the difference between the offset between the measured gravity tool face and the measured magnetic tool face and the estimated offset as the phase correction amount, and data obtained by correcting the magnetic field data with the phase correction amount as the corrected magnetic field data, and determines the attitude based on the acceleration data and the corrected magnetic field data. Effect of the Invention

[0007] According to the measuring device of the present invention, a phase correction amount is calculated to accommodate changes in the phase of the magnetic field due to the effects of eddy currents that occur in the metal housing covering the excavation section during excavation, and the posture is calculated using the phase correction amount, so that the posture of the excavation section can be accurately measured even during excavation. [Brief description of the drawings]

[0008] [Figure 1] FIG. 13 is a diagram showing an example of a correction operation process according to the prior art. [Diagram 2]This figure shows the inclination angle calculated using acceleration data output from a three-axis acceleration sensor and magnetic field data output from a three-axis magnetic sensor placed on the excavation part, while controlling the rotation speed of the excavation part, which has no metal housing, and fixing the posture. [Diagram 3] This figure shows the azimuth angle calculated using acceleration data output from a three-axis acceleration sensor and magnetic field data output from a three-axis magnetic sensor placed on the excavation part, which has no metal housing, while controlling the rotation speed of the excavation part and fixing the posture. [Figure 4] This figure shows the inclination angle calculated using acceleration data output from a three-axis acceleration sensor and magnetic field data output from a three-axis magnetic sensor placed in the housing of the excavation unit, while controlling the rotation speed of the excavation unit, which has a metal housing, and fixing the posture of the excavation unit. [Diagram 5] This figure shows the azimuth angle calculated using acceleration data output from a three-axis acceleration sensor and magnetic field data output from a three-axis magnetic sensor placed in the housing of an excavation unit, with the rotation speed of the excavation unit, which has a metal housing, fixed in position, while controlling the rotation speed. [Figure 6] FIG. 2 is a diagram showing an example of the functional configuration of a measurement system according to the present invention. [Figure 7] FIG. 4 is a diagram showing an example of a process flow of a measurement method according to the present invention. [Figure 8] This figure shows the inclination angle determined by the measurement method of the present invention, using acceleration data output from a three-axis acceleration sensor and magnetic field data output from a three-axis magnetic sensor placed in the housing of the excavation part, while controlling the rotation speed of the excavation part equipped with a metal housing and fixing the posture of the excavation part. [Figure 9] This figure shows the azimuth angle determined by the measurement method of the present invention, using acceleration data output from a three-axis acceleration sensor and magnetic field data output from a three-axis magnetic sensor placed in the housing of an excavation unit, while controlling the rotation speed of the excavation unit, which has a metal housing, and fixing the posture of the excavation unit. [Figure 10] FIG. 2 is a diagram showing an example of the functional configuration of a computer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described in detail. Note that components having the same functions are given the same reference numbers and duplicated explanations will be omitted. EXAMPLES

[0010] <Analysis> The measuring device which is the subject of the present invention is a device for measuring acceleration data (A x ,A y ,A z ) and the magnetic field data (M x ,M y ,M z ) to find the posture. A z is the acceleration component in the excavation direction. A x and A y are acceleration components perpendicular to the excavation direction and are mutually orthogonal. z is the magnetic force component in the drilling direction. M x and M. y are magnetic force components perpendicular to the excavation direction and are mutually orthogonal. Therefore, the acceleration data (A x ,A y ,A z ) and the magnetic field data (M x ,M y ,M z ) was used to determine the inclination angle and azimuth angle both when stationary and when rotating. Although there is no graph showing the results, the measured inclination angle does not change whether the excavation part is stationary or rotating. On the other hand, the azimuth angle measured changes from the value measured when the excavation part is stationary once rotation begins. In other words, it can be predicted that an error will occur in the azimuth angle when the excavation part rotates.

[0011] Next, we will show the results of an experiment conducted to confirm the prediction. While controlling the rotation speed of the excavation part, which does not have a metal housing, the posture was fixed and the acceleration data (A x ,A y ,A z) and the magnetic field data (M x ,M y ,M z The inclination angle and azimuth angle obtained using the azimuth angle are shown in Fig. 2 and Fig. 3, respectively. In addition, while controlling the rotation speed of the excavation unit equipped with a metal housing, the attitude was fixed and the acceleration data (A x ,A y ,A z ) and the magnetic field data (M x ,M y ,M z The inclination angle and azimuth angle obtained using the azimuth angle θ are shown in Fig. 4 and Fig. 5, respectively. The vertical axis on the left side of Fig. 2 and Fig. 4 indicates the inclination angle (deg), and the vertical axis on the left side of Fig. 3 and Fig. 5 indicates the azimuth angle (deg). The vertical axis on the right side of Fig. 2 to 5 indicates the set rotation speed (rpm) of the excavation part, and the horizontal axis indicates the time of measurement (hours:minutes:seconds). The hollow circles indicate the acceleration data (A x ,A y ,A z ) and magnetic field data (M x ,M y ,M z The squares show the results (measurements when stationary) obtained using the acceleration data (A x ,A y ,A z ) and magnetic field data (M x ,M y ,M z ) are used to obtain the results continuously and periodically. Note that when the excavator is rotating, the acceleration data (A x ,A y ,A z ) and magnetic field data (M x ,M y ,M z ) contains various noises due to vibrations, etc., so the tilt angle and azimuth angle are included in the state quantity of the Kalman filter, and the acceleration data (A x ,A y ,A z ) and magnetic field data (M x ,M y ,M z ) is used as input to calculate the tilt angle and azimuth angle using a Kalman filter.

[0012] Here, (a x ,a y ,a z ) is the acceleration data due to gravity, and a z is the gravitational acceleration component in the excavation direction, a x and a y is the gravitational acceleration component perpendicular to the excavation direction and is perpendicular to the excavation direction. In this case, the inclination angle (Inc) is defined as follows:

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[0013] As mentioned above, Non-Patent Document 1 shows that eddy currents are generated in a conductor that shields an alternating magnetic field. In this case, the geomagnetic field is constant, but the metal housing rotates. It is believed that this rotation generates eddy currents in the housing in the same way as in the case of shielding an alternating magnetic field. Non-Patent Document 1 also describes the magnetic field strength H inside the cylinder, where D is the diameter of the cylinder, d is the thickness of the cylinder, ρ is the resistivity of the metal, f is the frequency of the magnetic field, μ0 is the magnetic conductivity of air, and j is the imaginary unit. i and the magnetic field strength H when there is no cylinder o The relationship is shown as follows:

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[0014] <Example> FIG. 6 shows an example of the functional configuration of the measurement system of the present invention. FIG. 7 shows an example of the process flow of the measurement method of the present invention. The measurement system 10 of the present invention has a measurement device 100, an at least three-axis acceleration sensor 310, and an at least three-axis magnetic sensor 320. The at least three-axis acceleration sensor 310 and the at least three-axis magnetic sensor 320 are arranged in the excavation section of an underground excavator. The excavation section is covered with a metal housing, and the at least three-axis acceleration sensor 310 and the at least three-axis magnetic sensor 320 are housed in the metal housing. Theoretically, the measurement system described below functions as long as there is data from the three-axis acceleration sensor 310 and the three-axis magnetic sensor 320. However, for the purpose of improving accuracy, multiple acceleration sensors or magnetic sensors may be provided for one axis, or acceleration sensors and magnetic sensors such as four-axis or five-axis may be provided. Therefore, the above description uses the expression "at least three axes". Below, a case where the three-axis acceleration sensor 310 and the three-axis magnetic sensor 320 are provided will be described.

[0015] The measurement device 100 measures acceleration data (A x ,A y ,A z ) and the magnetic field data (M x ,M y ,M z ) is used to calculate the attitude. x ,A y ,A z ) and magnetic field data (M x ,M y ,M z) uses data that has been subjected to processing such as filtering and temperature compensation, rather than data directly output by the triaxial acceleration sensor 310 and triaxial magnetic sensor 320. The measuring device 100 includes a processor 105 that is controlled by a program and processes information. The processor 105 includes an attitude estimation unit 110, a phase correction amount calculation unit 170, and a memory 190. The attitude estimation unit 110 determines the attitude of the excavation part based on the acceleration data and magnetic field data. Note that "attitude" includes the inclination angle (Inc), azimuth angle (Azm), and dip angle (Dip). A z is the acceleration component in the excavation direction. A x and A y are acceleration components perpendicular to the excavation direction and are mutually orthogonal. z is the magnetic force component in the drilling direction. M x and M. y are magnetic force components perpendicular to the excavation direction and are mutually orthogonal. When the excavation part is rotating, the acceleration data (A x ,A y ,A z ) and magnetic field data (M x ,M y ,M z ) contains various noises due to vibrations, etc. The posture estimation unit 110 uses a conventional technique such as a Kalman filter to remove noise components and obtain acceleration data (a x ,a y ,a z ) and magnetic field data (M x ,M y ,M z ) to determine the inclination angle (Inc), azimuth angle (Azm), dip angle (Dip), gravity tool face (gTF), and magnetic tool face (mTF).

[0016] The posture estimation unit 110 estimates acceleration data (A x ,A y ,A z ) and magnetic field data (M x ,M y ,M z) is input, and initial values ​​such as the attitude are calculated (S101). Specifically, the initial values ​​of the inclination angle (Inc0), azimuth angle (Azm0), dip angle (Dip0), gravity tool face (gTF0), and magnetic tool face (mTF0) are calculated as follows:

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[0017] While the excavation unit is rotating, the phase correction amount calculation unit 170 calculates the offset between the gravity tool face and the magnetic tool face based on the attitude calculated by the attitude estimation unit 110, and records this in the memory 190 as the estimated offset (TFO) (S170). For example, while the excavation unit is rotating, the offset calculated from the most recently calculated inclination angle (Inc), azimuth angle (Azm), and dip angle (Dip) can be updated as the new estimated offset (TFO). A specific calculation method will be described later. In step S101 shown in FIG. 7, the attitude estimation unit 110 calculates acceleration data (A x ,A y ,A z ) and magnetic field data (M x ,M y ,M z The offset calculated from the gravity tool face (gTF) and the magnetic tool face (mTF) based on the gravity tool face (gTF) and the magnetic tool face (mTF) is set as the estimated offset (TFO) and is recorded in the memory 190. Specifically, the gravity tool face (gTF), the magnetic tool face (mTF), and the estimated offset (TFO) are TFO = mTF-gTF We can find it as follows.

[0018] The measurement device 100 measures acceleration data (A x ,A y ,A z ) and the magnetic field data (M x ,M y ,M z The posture estimation unit 110 acquires acceleration data (A x ,A y ,A z ) and magnetic field data (M x ,M y ,M z ) is input, noise components are removed using conventional technology such as a Kalman filter, and the inclination angle (Inc), azimuth angle (Azm), dip angle (Dip), gravity tool face (gTF), and magnetic tool face (mTF), which are the attitudes, are obtained (S110). If the noise components can be removed, conventional technology other than the Kalman filter may be used. When the Kalman filter is used, for example, the inclination angle (Inc), azimuth angle (Azm), dip angle (Dip), and gravity tool face (gTF) are included in the state quantities of the Kalman filter, and the acceleration data (A x ,A y ,A z ) and magnetic field data (M x ,M y ,M z ) is input and the state quantities, that is, the inclination angle (Inc), the azimuth angle (Azm), the dip angle (Dip), and the gravity tool face (gTF), are obtained using a Kalman filter. The state quantities of the Kalman filter may include other state quantities. For example, the rotation speed of the gravity tool face (gTF) may also be a state quantity. Here, (a x ,a y ,a z ) into acceleration data (A x ,A y ,A z ) contains the acceleration data of the gravity component (a x ,a y ,a z ) The measurement gravity tool face (mgTF), measurement magnetic force tool face (mmTF), acceleration data (a x ,a y ,az ), magnetic field data (M x ,M y ,M z ) is as follows:

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[0019] As explained in the analysis, the phase of the magnetic tool face changes during rotation due to the effects of eddy currents generated in the metal housing, etc. Therefore, the difference between the offset between the measured gravity tool face (mgTF) and the measured magnetic tool face (mmTF) and the estimated offset (TFO) is taken as the phase correction amount (pdm), which is defined as follows: pdm=mmTF-mgTF-TFO The estimated offset (TFO) is data recorded in memory 190. That is, the first time through the processing loop shown in Fig. 7, the estimated offset (TFO) is the one calculated in step S101, and the second and subsequent times through the processing loop, the estimated offset (TFO) is the one calculated in step S170 of the previous loop.

[0020] Magnetic field data (M x ,M y ,M z ) is corrected by the phase correction amount, and the corrected magnetic field data (m x ,m y ,m z ) have the following relationship:

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[0021] Acceleration data (a x ,a y ,a z ) and the corrected magnetic field data (m x ,m y ,m z ), the inclination angle (Inc), azimuth angle (Azm), and dip angle (Dip) have the following relationship:

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[0022] The phase correction amount calculation unit 170 calculates an estimated offset TFO from the inclination angle (Inc), azimuth angle (Azm), and dip angle (Dip) calculated by the attitude estimation unit 110 as follows:

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[0023] <Experiment> While controlling the rotation speed of the excavation part equipped with a metal housing, the posture is fixed and the acceleration data (A x ,A y ,A z ) and the magnetic field data (M x ,M y ,Mz ) are used to measure the inclination angle and azimuth angle obtained by the measurement method of the present invention including step S170 described in the embodiment. The vertical axis on the left side of Fig. 8 indicates the inclination angle (deg), and the vertical axis on the left side of Fig. 9 indicates the azimuth angle (deg). The vertical axis on the right side of Fig. 8 and Fig. 9 indicates the set rotation speed (rpm) of the excavation part, and the horizontal axis indicates the time of measurement (hours:minutes:seconds). Hollow circles indicate acceleration data (A x ,A y ,A z ) and magnetic field data (M x ,M y ,M z The squares show the results (measurements when stationary) obtained using the acceleration data (A x ,A y ,A z ) and magnetic field data (M x ,M y ,M z The results are shown in Fig. 1. The tilt angle and azimuth angle are included in the state quantity of the Kalman filter, and the acceleration data (A x ,A y ,A z ) and magnetic field data (M x ,M y ,M z ) is used as input to determine the inclination angle and azimuth angle using a Kalman filter. Figures 8 and 9 show that the inclination angle and azimuth angle can be estimated without being affected by the metal housing even when the excavator is rotating. This shows that the effects of eddy currents generated in the metal housing during rotation have been sufficiently reduced.

[0024] According to the measurement device of the present invention, a phase correction amount is calculated to deal with changes in the phase of the magnetic field caused by the influence of eddy currents generated in the metal housing covering the excavation part during excavation, and a phase delay of the magnetic sensor itself caused by rotation, and the attitude is calculated using the phase correction amount, so that the influence caused by the rotation of the excavation part can be reduced. Therefore, the attitude of the excavation part can be accurately measured even during excavation.

[0025] [Programs, recording media] The various processes described above can be implemented by loading a program for executing each step of the above method into the recording unit 2020 of the computer 2000 shown in FIG. 10, and operating the control unit 2010, input unit 2030, output unit 2040, display unit 2050, etc.

[0026] The program describing the processing contents can be recorded on a computer-readable recording medium, which may be, for example, a magnetic recording device, an optical disk, a magneto-optical recording medium, a semiconductor memory, or any other type of recording medium.

[0027] The program may be distributed, for example, by selling, transferring, lending, etc. portable recording media such as DVDs and CD-ROMs on which the program is recorded. Furthermore, the program may be distributed by storing the program in a storage device of a server computer and transferring the program from the server computer to other computers via a network.

[0028] A computer that executes such a program, for example, first stores the program recorded on a portable recording medium or the program transferred from a server computer in its own storage device. Then, when executing a process, the computer reads the program stored in its own recording medium and executes a process according to the read program. As another execution form of the program, the computer may directly read the program from the portable recording medium and execute a process according to the program, or may execute a process according to the received program each time a program is transferred from the server computer to the computer. The above-mentioned process may be executed by a so-called ASP (Application Service Provider) type service that realizes a processing function only by issuing an execution instruction and obtaining a result, without transferring a program from the server computer to the computer. Note that the program in this embodiment includes information used for processing by an electronic computer and equivalent to a program (data that is not a direct command to the computer but has a nature that specifies the processing of the computer, etc.).

[0029] In addition, in this embodiment, the present device is configured by executing a specific program on a computer, but at least a part of the processing contents may be realized by hardware. [Explanation of symbols]

[0030] 100 Measuring Equipment 105 processors 110 Posture estimation section 170 Estimated offset calculation unit 190 Memory 310 Acceleration Sensor 320 Magnetic Sensor

Claims

1. A measurement device for determining a posture using acceleration data output from at least a three-axis acceleration sensor and magnetic field data output from at least a three-axis magnetic sensor disposed in an excavation section of an underground excavator, comprising: A processor is provided. The processor, a posture estimation unit that processes the acceleration data to obtain acceleration data (Ax, Ay, Az), processes the magnetic field data to obtain magnetic field data (Mx, My, Mz), and obtains a posture of the excavation unit based on the acceleration data (Ax, Ay, Az) and the magnetic field data (Mx, My, Mz); a phase correction amount calculation unit that calculates an offset between the gravity tool face and the magnetic tool face and sets the offset as an estimated offset; having The offset between the gravity tool face (gTF) and the magnetic tool face (mTF) calculated based on the acceleration data (A x , A y , A z ) and the magnetic field data (M x , M y , M z ) when the excavation part is stationary is defined as an estimated offset; The posture estimation unit is When the excavation section is rotating, a measured gravity tool face (mgTF) is obtained based on the acceleration data (ax, ay, az) due to gravity contained in the acceleration data (Ax, Ay, Az), and a measured magnetic force tool face (mmTF) is obtained based on the magnetic field data (Mx, My, Mz); a difference between the offset between the measurement gravity tool face and the measurement magnetic force tool face and the estimated offset is defined as a phase correction amount, and data obtained by correcting the magnetic field data with the phase correction amount is defined as corrected magnetic field data; The attitude is calculated based on the acceleration data and the corrected magnetic field data. A measuring device characterized by:

2. The measurement device according to claim 1, The attitude calculated by the attitude estimation unit is an inclination angle, an azimuth angle, and a dip angle, The phase correction amount calculation unit updates the estimated offset with the offset of the gravity tool face and the magnetic tool face calculated from the inclination angle, azimuth angle, and dip angle calculated by the attitude estimation unit while the excavation unit is rotating. A measuring device characterized by:

3. The measurement device according to claim 2, (m ｘ , m ｙ , m ｚ ) is the corrected magnetic field data, The inclination angle Inc, the azimuth angle Azm, and the dip angle Dip are ##EQU00015## have a relationship with A measuring device characterized by:

4. The measuring device according to claim 2 or 3, Let Inc be the inclination angle calculated by the attitude estimation unit, Azm be the azimuth angle calculated by the attitude estimation unit, and Dip be the dip angle calculated by the attitude estimation unit, The phase correction amount calculation unit calculates the estimated offset TFO as follows: ##EQU00016## Ask for something like A measuring device characterized by:

5. The measurement device according to any one of claims 1 to 4, pdm is the phase correction amount, (M ｘ , M ｙ , M ｚ ) is the magnetic field data, (m ｘ , m ｙ , m ｚ ) is the corrected magnetic field data, The magnetic field data and the corrected magnetic field data ##EQU00017## have a relationship with A measuring device characterized by:

6. The measurement device according to any one of claims 1 to 5, The posture estimation unit is The posture obtained when the excavation unit is stationary is set as the initial value of the posture. A measuring device characterized by:

7. A measurement method using acceleration data output from at least a three-axis acceleration sensor and magnetic field data output from at least a three-axis magnetic sensor disposed in an excavation section of an underground excavator, comprising: a posture estimation process for processing the acceleration data to obtain acceleration data (Ax, Ay, Az), processing the magnetic field data to obtain magnetic field data (Mx, My, Mz), and obtaining the posture of the excavation unit based on the acceleration data (Ax, Ay, Az) and the magnetic field data (Mx, My, Mz); a phase correction amount calculation process for calculating an offset between the gravity tool face and the magnetic tool face as an estimated offset; Run The offset between the gravity tool face (gTF) and the magnetic tool face (mTF) calculated based on the acceleration data (A x , A y , A z ) and the magnetic field data (M x , M y , M z ) when the excavation part is stationary is defined as an estimated offset; In the posture estimation process, When the excavation section is rotating, a measured gravity tool face (mgTF) is obtained based on the acceleration data (ax, ay, az) due to gravity contained in the acceleration data (Ax, Ay, Az), and a measured magnetic force tool face (mmTF) is obtained based on the magnetic field data (Mx, My, Mz); a difference between the offset between the gravity measuring tool face and the magnetic force measuring tool face and the estimated offset is a phase correction amount, and data obtained by correcting the magnetic field data with the phase correction amount is a corrected magnetic field data; The attitude is calculated based on the acceleration data and the corrected magnetic field data. A measuring method comprising:

8. The measurement method according to claim 7, The attitude obtained by the attitude estimation process is an inclination angle, an azimuth angle, and a dip angle, The phase correction amount calculation step updates an estimated offset with an offset between a gravity tool face and a magnetic tool face calculated from an inclination angle, an azimuth angle, and an inclination angle calculated in the attitude estimation step while the excavation unit is rotating. A measuring method comprising:

9. The measurement method according to claim 8, (m ｘ , m ｙ , m ｚ ) is the corrected magnetic field data, The inclination angle Inc, the azimuth angle Azm, and the dip angle Dip are [0018] have a relationship with A measuring method comprising:

10. The measurement method according to claim 8 or 9, Let Inc be the inclination angle obtained in the attitude estimation process, Azm be the azimuth angle obtained in the attitude estimation process, and Dip be the dip angle obtained in the attitude estimation process, The phase correction amount calculation step calculates the estimated offset TFO as follows: [0019] Ask for something like A measuring method comprising:

11. The measurement method according to any one of claims 7 to 10, pdm is the phase correction amount, (M ｘ , M ｙ , M ｚ ) is the magnetic field data, (m ｘ , m ｙ , m ｚ ) is the corrected magnetic field data, The magnetic field data and the corrected magnetic field data [0020] have a relationship with A measuring method comprising:

12. The measurement method according to any one of claims 7 to 11, The pose estimation process includes: The posture obtained when the excavation unit is stationary is set as the initial value of the posture. A measuring method comprising:

13. A measurement program for causing a computer to execute the measurement method according to any one of claims 7 to 12.

14. 13. A computer-readable recording medium having recorded thereon a measurement program for causing a computer to execute the measurement method according to any one of claims 7 to 12.

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