Method for locating a boring tool

• US 6,002,258 A
• Filed: 04/13/1998
• Issued: 12/14/1999
• Est. Priority Date: 03/01/1991
• Status: Expired due to Fees

• Current Assignee: Merlin Technologies Incorporated
• Original Assignee: Digital Control Incorporated
• Inventors: Mercer, John E.
• Primary Examiner(s): Snow, Walter E.
• Application Number:
  US09/059,456
• Time in Patent Office: 610 Days
• Field of Search: 324/326, 324/327, 324/328, 324/329, 324/226, 324/262, 324/207.23, 324/207.26, 324/207.16, 324/207.17, 175/40, 175/45, 342/459
• US Class Current: 324/326
• CPC Class Codes: E21B 47/0228 using electromagnetic energy or detectors therefor
• CPC Class Codes: E21B 47/0232 at least one of the energy sources or one of the detectors being located on or above the ground surface
• CPC Class Codes: G01C 9/06 Electric or photoelectric indication or reading means
• CPC Class Codes: G01C 9/20 the indication being based on the inclination of the surface of a liquid relative to its container
• CPC Class Codes: G01V 3/15 specially adapted for use during transport, e.g. by a person, vehicle or boat
• CPC Class Codes: G01V 3/165 operating with magnetic or electric fields produced or modified by the object or by the detecting device with electromagnetic waves G01V3/17

Abstract

The present invention provides a locator/monitor capable of locating a boring tool and monitoring the progress of the tool for control purposes. The locator/monitor may be used in expedited locating methodology and straightforward calibration techniques of the present invention. A durable and cost effective pitch sensor is also provided by the present invention. In addition, the present invention provides a slotted transmitter housing formed of an electrically conductive material, where the magnetic field generated by the transmitter is capable of penetrating to the surface.

Claims

1. In a method for locating a boring tool that moves through the ground from a first point to a second point in directions dependent on the roll orientation of the boring tool and during which time the roll orientation of the boring tool is controllably changeable throughout 360°

of roll orientation in order to steer it between said first and second points, said method using (1) a transmitter and power supply carried by the boring tool within an electrically conductive housing for transmitting to an above ground location an electromagnetic signal containing information which is used in obtaining the location of the boring tool and (2) a receiver located at said above ground location for receiving and processing said electromagnetic signal whereby to determine the location of the boring tool, the improvement comprising the steps of;

transmitting said electromagnetic signal continuously as said boring tool moves from said first point to said second point independent of the roll orientation of the boring tool at any point throughout its 360°

of roll orientation, whereby the transmitter is able to transmit and the receiver is able to receive said information containing signal irrespective of the roll orientation of the boring tool so that the depth of the boring tool can be determined regardless of its direction of movement from said first point to said second point; and

maintaining the strength of said signal substantially constant with time at any given point relative to said transmitter as the signal is being continuously transmitted, whereby the depth of the boring tool can be continuously monitored as it moves from said first point to said second point.

2. The improvement according to claim 1, wherein said transmitter defines an axis, wherein said power supply is provided with a regulator for causing said transmitter to transmit said electromagnetic signal at said substantially constant intensity and wherein said electrically conductive housing is provided with a series of slots configured in a way which cooperates with said regulated transmitter such that said signal emanates from said housing 360°

around said transmitter axis with said substantially constant intensity.

3. In a method for locating a boring tool that moves through the ground from a first point to a second point during which time at least the roll orientation of the boring tool changes, said method using (1) a transmitter defining an axis and power supply carried by the boring tool within an electrically conductive housing for transmitting by means of a dipole field to an above ground location an electromagnetic signal containing information which is used in obtaining the location of the boring tool and (2) a receiver located at said above ground location for receiving and processing said electromagnetic signal, whereby to determine the location of the boring tool, the improvement comprising the steps of:

(a) providing the power supply with a regulator for causing said transmitter to transmit said electromagnetic signal at a substantially constant intensity with time at any given point with respect to said transmitter;

(b) providing the housing with a series of slots configured in a way which cooperates with said regulated transmitter such that said signal emanates from said housing 360°

around said transmitter axis with said substantially constant intensity;

(c) determining the proportionality constant of said dipole field, which proportionality constant relates distance to the cube root of the magnetic field strength of said dipole field; and

(d) using said proportionality constant and said electromagnetic signal, causing said receiver to determine the depth of said boring tool.

4. In a method for locating a boring tool that moves through the ground from a first point to a second point, said method using (1) a given transmitter within said boring tool for transmitting by means of a dipole field to an above ground location an electromagnetic signal containing information including the signal'"'"'s field strength which is used in obtaining the depth of the boring tool and (2) a given receiver located at said above ground location for receiving and processing said electromagnetic signal, whereby to determine the depth of the boring tool, the improvement comprising the steps of:

(a) providing a specific positional relationship between said transmitter and receiver and, while maintaining that positional relationship, transmitting a CONSTANT electromagnetic signal with time from said transmitter and receiving said CONSTANT signal from said receiver;

(b) obtaining distance and electromagnetic signal field strength measurements (i) based on said positional relationship between the transmitter and receiver and (ii) based on the transmission and reception of said constant signal by said transmitter and receiver, respectively, and using those measurements, establishing a proportionality constant k of said dipole field FOR SAID GIVEN TRANSMITTER AND RECEIVER, which proportionality constant relates distance to the cube root of the magnetic field strength of said dipole field; and

(c) thereafter, using said proportionality constant and a CONSTANT electromagnetic signal with time, causing said receiver to determine the depth of said boring tool.

5. The improvement according to claim 4 wherein two distance measurements d₁ and d₂ making up said positional relationship and two field strength measurements B₁ and B₂ based on said calibration signal are obtained and used to establish said proportionality constant, said measurements being based on the following equations:

space="preserve" listing-type="equation">B.sub.1= k/d.sub.1.sup.3

space="preserve" listing-type="equation">B.sub.2= k/d.sub.2.sup.3.

6. The improvement according to claim 4 wherein one distance measurement d₁ making up said positional relationship and one field strength measurements B₁ based on said calibration signal are used to establish said proportionality constant, said measurements being based on the following equation:

space="preserve" listing-type="equation">B.sub.1= k/d.sub.1.sup.3.

7. The improvement according to claim 6 wherein said distance measurement is obtained using an independent measurement system.

8. The improvement according to claim 7 wherein said measurement system is separate from said receiver.

9. In a method of locating the depth of a boring tool that moves through the ground from a first point to a second point, said method using ( 1) a given transmitter defining an axis and power supply carried by the boring tool for transmitting by means of a dipole field to an above ground location an electromagnetic signal containing information including the signal'"'"'s field strength which is used in obtaining the depth of the boring tool and (2) a given receiver located at said above ground location for receiving and processing said electromagnetic signal, whereby to determine the depth of the boring tool, the improvement comprising the steps of:

(a) providing a specific positional relationship between said transmitter and receiver and, while maintaining that positional relationship, transmitting a CONSTANT electromagnetic calibration signal with time from said transmitter and receiving said CONSTANT signal from said receiver;

(b) obtaining a distance measurement d₁ and an electromagnetic signal field strength measurement B₁ (i) based on said positional relationship between the transmitter and receiver and (i) based on the transmission and reception of said CONSTANT calibration signal by said transmitter and receiver, respectively, and using those measurements, establishing the proportionality constant k of said dipole field FOR SAID GIVEN TRANSMITTER AND RECEIVER based on the equation B₁₌ k/d₁³ ; and

(c) thereafter, using said proportionality constant and a CONSTANT electromagnetic signal, causing said receiver to determine the depth of said boring tool.

10. In a method of locating the depth of a boring tool that moves through the ground from a first point to a second point, said method using (1) a given transmitter in the boring tool for transmitting by means of a dipole field to an above ground location an electromagnetic signal containing information including the signal'"'"'s field strength which is used in obtaining the depth of the boring tool, and (2) a given receiver located at said above ground location for receiving and processing said electromagnetic signal, whereby to determine the depth of the boring tool, the improvement comprising the steps of:

(a) obtaining a proportionality constant for said given transmitter and said given receiver;

(b) thereafter, using said given transmitter, transmitting said electromagnetic signal as said boring tool moves from said first point to said second point;

(c) causing said given receiver to receive and process said last-mentioned electromagnetic signal using the obtained proportionality constant in the processing of said received signal; and

(d) monitoring and displaying the depth of said boring tool as it moves through the ground from said first point to said second point using the signal processed by said receiver.

11. The improvement according to claim 10 wherein the step of obtaining said proportionality constant includes the steps of placing said given transmitter and receiver in a positional relationship with one another and obtaining a distance measurement based on said positional relationship.

12. The improvement according to claim 11 wherein said distance measurement is obtained using a measurement system independent of said receiver.

13. In a method of locating the depth of a given boring tool that moves through the ground from a first point to a second point, said method using (1) a given transmitter in the boring tool for transmitting by means of a dipole field to an above ground location an electromagnetic signal containing information including the signal'"'"'s field strength which is used in obtaining the depth of the boring tool, and (2) a given receiver located at said above ground location for receiving and processing said electromagnetic signal, whereby to determine the depth of the boring tool, the improvement comprising the step of:

using the electromagnetic signal of said given transmitter and using the given receiver, obtaining the proportionality constant particular to the specific combination of that transmitter and that receiver.

14. The improvement according to claim 13 wherein said proportionality constant is obtained while said transmitter is in said given boring tool such that the proportionality constant is particular not only to said transmitter and said receiver but also to said given boring tool.