| 摘要 |
PROBLEM TO BE SOLVED: To accurately measure the position of a propulsion head in spite of spatial turbulence of magnetism. SOLUTION: This propulsion head position direction measurement device is provided with first and second magnetic field detectors 102 and 103 arranged in the same propulsion head 100 along the propulsion direction, a propulsion distance measurement device 120 measuring a propulsion distance of the propulsion head, a magnetic field azimuth estimation part 224 estimating a magnetic field azimuth of an imaginary point in the propulsion directional front part from magnetic field azimuths measured by the magnetic field detectors 102 and 103, and a horizontal position direction computing 230 computing a horizontal direction change in the propulsion head on the basis of the magnetic field azimuth estimated by the magnetic field azimuth estimation part 224 and the magnetic field azimuths found by the magnetic field detectors 102 and 103. |
