Method of locating the position of linear objects

• US 9,664,810 B2
• Filed: 04/22/2014
• Issued: 05/30/2017
• Est. Priority Date: 04/23/2013
• Status: Active Grant

• Current Assignee: Takachiho Sangyo Co., Ltd.
• Original Assignee: Takachiho Sangyo Co., Ltd.
• Inventors: Mizuno, Morio
• Primary Examiner(s): Nguyen, Tung X
• Assistant Examiner(s): Hawkins, Dominic
• Application Number:
  US14/258,820
• Publication Number:
  US 20140312904A1
• Time in Patent Office: 1,134 Days
• Field of Search: 324326, 324323, 324327
• CPC Class Codes: G01V 3/104 using several coupled or uncoupled coils G01V3/101 takes precedence

Abstract

A method of locating a position of a linear object, including arranging a first and a second reactor around a measuring point, the first reactor generating an induced voltage corresponding to an X-direction component of a magnetic field, the X direction perpendicular to a running direction of the object, and the second reactor generating an induced voltage corresponding to a Y-direction component of the field, the Y direction perpendicular to the X-direction and the running direction; obtaining a first reactor induced voltage and a second reactor induced voltage; setting an X-distance as a first distance from the point to the object center, and setting the Y-distance as a second distance; and estimating a direction in which the linear object is located as viewed from the point, by regarding an X-distance to Y-distance ratio as equal to a ratio of the first voltage to the second voltage multiplied by a coefficient.

Claims

1. A method of locating the position of a linear object, wherein a running direction of the linear object is known, the method comprising:

generating a circumferential alternating magnetic field about a linear object;

arranging a first and a second reactor around a measurement point away from the linear object, the first reactor comprising a first coil and a second coil differentially connected so that the first reactors produces a first reactor induced voltage corresponding to an X-direction field gradient of an X-direction component of the magnetic field, the X direction being perpendicular to the known running direction of the linear object, and the second reactor comprising a third coil and a fourth coil differentially connected so that the second reactor produces a second reactor induced voltage corresponding to a Y-direction field gradient of an X-direction component of the magnetic field, the Y direction being perpendicular both to the X-direction and to the running direction of the linear object,

obtaining the first reactor voltage corresponding to the X-direction field gradient from the first reactor and the second reactor voltage corresponding to the Y-direction field gradient from the second reactor; and

determining an estimated direction in which the linear object is located as viewed from the measurement point, by equating a ratio of an X-distance to a Y-distance and a ratio of the first reactor voltage to the second reactor voltage multiplied by a certain coefficient, wherein the X-distance is a distance from the measurement point to the linear object in the X-direction, and the Y-direction is a distance from the measurement point to the linear object in the Y-direction.

2. The method of locating the position of a linear object according to claim 1,

wherein the first and second coils are spaced apart from each other, and arranged on opposite sides of the measurement point in the X-direction,

wherein the third and fourth coils are spaced apart from each other, arranged on opposite sides of the measurement point in the Y-direction, and

wherein the first, second, third, and fourth coils each have an axis aligned in the X-direction.

3. The method of claim 2,

wherein the step of determining the estimated direction includes removing an error in proportion to the X-distance from the ratio of the first reactor voltage to the second reactor voltage.

4. The method of claim 2, further comprising:

obtaining a third coil voltage induced in the third coil by the alternating field, and a fourth coil voltage induced in the fourth coil by the alternating field;

calculating the Y-distance based on the third and fourth coil voltages while assuming the X-distance as zero; and

correcting the calculated Y-distance based on the ratio of the first reactor voltage to the second reactor voltage.

5. The method of claim 4, further comprising

calculating the X-distance based on the corrected Y-distance and the ratio of the first reactor voltage to the second reactor voltage.