HK1189257A - Locator using two horizontally displaced measurement points - Google Patents

Description

Locator using two horizontally displaced measurement points

This application is a divisional application entitled application number 200810168743.4 entitled "positioner using two horizontally displaced measurement points" filed on a date of 2008, 9, 28.

Technical Field

The present invention relates generally to the field of locating underground targets and, more particularly, to locating and tracking signals or transmitters in the field of operating horizontal drilling machines.

Background

Horizontal Directional Drilling (HDD) processes typically use walk-over tracking techniques to track the drilling or installation process to quickly find the surface location directly above the drill bit or back reamer bit and to determine the depth of the drill bit or back reamer bit from the surface location. The primary tracking tools are underground transmitters and handheld surface receivers. Transmitters disposed in or in close proximity to a boring tool or a back reamer bit typically emit a dipole produced by a single coil dipole antennaA magnetic field. The emitted dipole magnetic field can be used both for localization and for communication with an overhead surface receiver.

Conventional receivers typically include an antenna arrangement with three antennas mounted on each of three cartesian axes. When the antenna devices measure dipole magnetic fields, the output of each antenna is proportional to the magnitude of the magnetic flux density measured along the axis of the particular antenna. The signals from the antennas are mathematically analyzed to provide information about the relative position of the boring tool. The method of locating the dipole magnetic field, and hence the boring tool, typically comprises two steps: its position is determined along the z-axis (longitudinal) and then along the y-axis (left and right). Those of ordinary skill in the art will appreciate that the receiver is capable of positioning the transmitter in the longitudinal direction (along the z-axis) using the amplitude and phase of the horizontal and vertical magnetic field components generated by the transmitter measured in a vertical plane (the x-z plane) that is orthogonal to the surface and extends through the transmitter axis. In the case where the transmitter is not in a horizontal plane and therefore the pitch of the transmitter is not 0, the determined position of the transmitter may or may not be directly below the receiver. The receiver can also determine the position of a single transmitter in the left-right direction using the amplitude and phase of the dipole magnetic field in the horizontal plane (y-z plane). However, the determination of the left-right direction can only be used in front of or behind the transmitter, since there is no y-component for the dipole magnetic field when the receiver is directly above the transmitter (so that z = 0). There is currently no satisfactory method of positioning the radiator in both the longitudinal and left-right directions while the antenna assembly is directly above the radiator.

Disclosure of Invention

The invention relates to a method for tracking a source of an underground magnetic field. The method includes maintaining the receiver assembly in a substantially horizontal plane, simultaneously detecting the magnetic field from the magnetic field source in three dimensions at each of two different points of the receiver, moving the receiver in a horizontal plane until the magnetic field is measured at each of the two pointsUntil the flux angles are zero, and then using the measured magnetic field data to calculate the position of the magnetic field source in three dimensions relative to the receiver.

The invention further relates to a receiver system for determining the position of a magnetic field source. The receiver includes a support including a handle, two and only two three-dimensional antennas supported by the support and adapted to detect a magnetic field from a magnetic field source, and a processor adapted to receive antenna signals from each of the two antenna assemblies and to determine a position of the magnetic field source relative to the support using the antenna signals. The holder is adapted to maintain the two antennas in a substantially horizontal plane when the holder is held in a hand grip.

In an alternative embodiment, the present invention is directed to a receiver system for detecting a signal from a magnetic field source. The receiver includes a support, at least one antenna assembly supported by the support and adapted to detect a magnetic field from a magnetic field source, a first filter assembly adapted to receive a signal from the at least one antenna assembly and output a first filtered signal, a second filter assembly adapted to receive a signal from the at least one antenna assembly and output a second filtered signal, and a processor adapted to receive the first and second filtered signals from the two filter assemblies, respectively, and determine whether data regarding the magnetic field from the magnetic field source has been transmitted. The first filter component includes at least one narrow band filter. The second filter component includes at least one wideband filter.

Yet another application of the present invention relates to a method for guiding a boring tool assembly toward and past a target. The method includes positioning a receiver assembly including two antenna assemblies in a substantially horizontal plane at a target location, simultaneously detecting a magnetic field from the boring tool assembly in three dimensions at each of the two antenna assemblies, and then calculating a position of the boring tool assembly in a vertical plane including the path of the borehole using the magnetic fields measured by the two antenna assemblies. The receiving assembly is positioned such that both antenna assemblies are located in advance of the boring tool assemblyAnd (5) determining the drilling path.

Drawings

Fig. 1 is a schematic diagram of a horizontal directional drilling system and tracking system for drilling a horizontal borehole constructed in accordance with the present invention.

Fig. 2 is a perspective view of a receiver assembly constructed in accordance with the present invention.

Fig. 3 is a partially cut-away perspective view of an antenna assembly for use with the present invention.

FIG. 4 is a block diagram of a portable zone monitoring system configured to detect and process signals transmitted by a boring tool.

FIG. 5 is a flow chart illustrating a method for improving transmitter positioning accuracy.

Fig. 6 is a geometric representation of the relationship between a transmitter and a tilted receiver.

Fig. 7 is another geometric representation of the relationship between the transmitter and the tilted receiver.

Fig. 8 is a schematic diagram of the relationship between a receiver and a transmitter for another method of receiver use.

Fig. 9 is a schematic diagram of a preferred embodiment for a receiver display when the receiver is used in the method of fig. 8.

Detailed Description

Referring now to the drawings in general, and to FIG. 1 in particular, there is shown a horizontal directional drilling system ("HDD") system 10 for use with the present invention.Figure 1 illustrates the effectiveness of horizontal directional drilling by demonstrating the ability to drill a borehole 12 without affecting the above-ground structure, i.e. the roadway or sidewalk represented by reference numeral 14. To pierce or drill the borehole 12, the drill string 16 with the drill bit 18 is rotationally driven by a rotary drive system 20. When the HDD system 10 is used to drill a borehole 12, monitoring the position of the drill bit 18 is critical to the accurate location of the borehole and subsequent installation of the facility. The present invention relates to a system 22 and method for tracking and monitoring a boring tool assembly 24 during horizontal directional boring operations. Although the invention is shown for use in a drilling system, the invention is equally applicable to pullback reaming operations in which the borehole is enlarged and prepared for installation of the required facilities.

The HDD system 10 of the present invention is adapted to provide service substantially horizontally below ground, such as below a roadway 14, building, river, or other obstruction. The tracking system 22 used in the HDD system 10 is particularly adapted to provide accurate three-dimensional positioning of the boring tool assembly 24. The positioning and monitoring operation of the present tracking system 22 is advantageous in that it can successfully reach an upper position of the drill bit 18 with a single movement or minimal coordinated movements. The foregoing and other advantages and features of the invention will become apparent from the following description of the preferred embodiments.

With continued reference to FIG. 1, the HDD system 10 includes a drill press 28 operatively connected to the boring tool assembly 24 through the drill string 16. The boring tool assembly 24 preferably includes a drill bit 18 or other directional boring tool, and electronics 30. The electronic device 30 includes a transmitter 32, or magnetic field source, for transmitting signals through the surface. Preferably the transmitter 32 comprises a dipole antenna that emits a dipole magnetic field. The electronics 30 may also include a plurality of sensors 34 for detecting operating characteristics of the boring tool assembly 24 and the drill bit 18. The plurality of sensors 34 may generally include sensors such as a roll sensor to measure the roll position of the drill bit 18, a pitch sensor to measure the pitch of the drill bit, a temperature sensor to measure temperature within the electronics 30, and a voltage transmitter to indicate the status of the batteryA sensor is provided. The information detected by the plurality of sensors 34 preferably comes from signals transmitted by the transmitter 32 on the boring tool assembly 24 using modulation or other well-known techniques.

Referring now to FIG. 2, a preferred embodiment of the tracking system 22 of the present invention is shown. The tracking system 22 includes a receiver assembly 36. The receiver assembly 36 includes a support 38, a computer processor 40, and first and second antenna arrangements 41 and 42 supported by the support. A processor 40 is supported by the support 38 and operatively connected to the antenna devices 41 and 42. The stand 38 is preferably of lightweight construction and can be carried by an operator using a handle 44. In the preferred embodiment, the receiver assembly 36 also includes a visual display screen 46 and a battery 48 for powering the various parts of the receiver assembly. The visual display screen 46 may be adapted to provide a visual depiction of the tracking system 22 relative to the drill bit 18 or transmitter 32, as well as other information useful to the operator. The receiver assembly 36 may also include a transmit antenna (not shown) for transmitting information from the receiver assembly to the drill press 10 or other remote system (not shown).

The antenna devices 41 and 42 are supported on the support 38 and are spaced apart from each other by a known distance and a known relative position. Preferably, the antenna devices 41 and 42 are arranged on the stand 38 such that when the stand is held in a substantially horizontal plane, the antennas will also lie in a horizontal plane. More preferably, the antennas are separated from each other by a distance of 30 inches. More preferably, the support 38 may define an axis between the antenna devices 41 and 42. It will be appreciated by those skilled in the art that the greater the distance or span between antennas, the greater the resolution and accuracy that can be provided. Other receiver configurations may be used so long as the antenna assemblies 41 and 42 are capable of separating the magnetic field in a rectangular coordinate system at the antenna mounting location on each of the brackets 38.

Each of the antenna devices 41 and 42 is preferably a three-dimensional antenna. More preferably, the antennas 41 and 42 are adapted to measure the total magnetic field at their respective locations on the support 38. Preference is given toEach antenna 41 and 42 includes three orthogonal antennas to measure the magnetic field along its particular axis of sensitivity. The signals measured by the three orthogonal antennas are each squared, summed and squared to obtain the total magnetic field. The calculation assumes that the sensitivity of each antenna is the same and that the center of each antenna coincides with the centers of the other two antennas so that the antenna arrangement measures the total magnetic field at some single location in space. The measurements and calculations are also simplified in that the antennas 41 and 42 are oriented and aligned in the same way with respect to each other. However, if the antennas 41 and 42 are not directed in the same direction, the calculation may be corrected (adjustment) to compensate for the difference in arrangement.

Referring now to fig. 3, a preferred embodiment of an antenna 41 or 42 for use in the present invention is shown. The antenna 42 includes a support structure 50 that defines three panels 52 for each of the three receive coils 54a, 54b, and 54 c. The support structure 50 is preferably made of a lightweight plastic and is machined in a manner that allows all three panels 52 to be dimensionally identical. More preferably, the support structure 50 has a substantially cubic shape and each of the three panels 52 defines a rectangular apertured region having a center point. More preferably, the panels 52 are oriented orthogonally to each other such that the center points coincide. Due to the panel structure, the coils 54 also all have coincident center points and their sensitivities are substantially the same. An antenna arrangement suitable for use in the present invention is more fully disclosed in commonly assigned U.S. patent application No. 11/382,644, the contents of which are hereby incorporated by reference. It will be appreciated by those skilled in the art that other embodiments of the three-dimensional antennas 41 and 42, such as ferrite rod antennas or printed circuit boards, may also be used.

Referring now to FIG. 4, a block diagram of a preferred embodiment of the receiver assembly 36 of the present invention is shown. The antenna devices 41 and 42, as previously described, measure the change in the magnetic field from the source transmitter 32. The detected change in the magnetic field results in an induced voltage in response to the magnetic field of the transmitter 32. The voltages from the antennas 41 and 42 are sent to a filter 60 and an amplifier 62. FilteringThe effect of other signals received by the antennas 41 and 42 from local noise sources is cancelled by the unit 60. The amplifier 62 amplifies the signals received by the antennas 41 and 42. The a/D converter 64 is used to convert analog waveform information into digital data.

The digital data from the a/D converter 64 is then sent to a central processing unit 66 (CPU) to calculate the position of the transmitter 32 relative to the receiver assembly 36. The CPU 66 may include a Digital Signal Processor (DSP) and a microcontroller. The CPU 66 decodes the information from the a/D converter 64 and performs calculations to determine the location of the transmitter in a manner to be described below. The CPU 66 may also discern information emanating from the magnetic field to determine battery status, pitch, roll, and other information about the boring tool assembly 24.

Receiver assembly 36 may also include one or more sensors 68 for measuring operational information about receiver assembly 36. For example, one or more accelerometers, or other known tilt and orientation sensors or magnetic compasses, may provide information regarding the roll position or tilt of receiver 36. The information from the sensor 68 is sent to the a/D converter 64 where the DSP can make calculations to compensate for the receiver 36 not being held precisely in the horizontal plane.

In a preferred embodiment, the receiver assembly 36 further includes a user interface 70 having a plurality of buttons, joysticks, and other input devices. An operator may enter information for use by CPU 66 through user interface 70. Information entered via the user interface 70 or determined or used by the CPU 66 may be displayed to the operator on a visual display screen 72. The receiver assembly 36 also includes a radio antenna 74 for transmitting information from the CPU 66 to a remote unit, such as the drill press 10.

Receiver 36 is preferably powered by a battery assembly 76 and a power conditioning system 78. Battery assembly 76 may include a plurality of batteries of the C-cell type, although other power sources are contemplated such as rechargeable batteries, solar cells orA fuel cell. The power conditioning system 78 may include a linear regulator or a switch mode regulator to power the various components of the receiver 36.

The present invention also provides a method and filter arrangement for improving the accuracy and processing of communications and signals received via the antennas 41 and 42. One preferred method of communication of information from transmitter 32 is a combination of on-off keying ("OOK") communication and differential phase shift keying ("DPSK") communication. In a preferred method, the synchronization sequence includes turning off the signal from the transmitter 32 for a short period of time. The receiver 36 is preferably programmed to recognize the "off" time in the present scheme as a synchronization period and provide the receiver with an opportunity to measure the noise floor. The "off" time is preferably a time sufficient for receiver 36 to measure the noise floor. The bit rate of the present communication scheme is preferably very close to the optimal bit rate required to transmit data from the transmitter 32. Conventional DPSK communication is then preferably used to transfer information from transmitter 32 to receiver 36. The present communication scheme is further advantageous because the transmitter 32, which has a synchronization period characteristic, always transmits a signal to the receiver 36 and the receiver is thus able to locate the transmitter substantially continuously.

An example of a transmission using the communication scheme of the present invention would include a 1 second duration packet. The packet preferably begins with a 50ms period during which the transmitter is not transmitting but is in an "off" state. The transmitter 32 is then turned on for a period of 50ms during which no phase shift is allowed so that a phase reference can be generated and recognized by the receiver 36. DPSK is then preferably used at 60bps to efficiently transmit the remaining 54 bits of information. Receiver 36 preferably parses the packet into 10 6-bit non-zero characters. More preferably, the first 6-bit character is treated as a synchronization sequence and the next 9 6-bit characters are data. The protocol for these characters may be constructed in any convenient manner to transmit information such as scroll position, pitch, temperature, etc.

In communication with and transmitting fromIn another method of transmitting information from the transmitter 32, rotation of the boring tool assembly 24 is stopped and the tool assembly and transmitter are maintained in a constant roll position. Preferably, the tool assembly 24 and transmitter 32 are rotated to a predetermined roll angle and allowed to remain fixed for a predetermined period of time. More preferably, the transmitter 32 is allowed to remain stationary for at least five seconds. If the transmitter 32 maintains a predetermined roll angle for a period of time, the transmitter 32 can be programmed to cease communication and transmit an unmodulated simple carrier signal. When the transmitter 32 is rotated again, the information communication of the modulated signal is restored. Alternatively, the transmitter may send an unmodulated scroll position signal when the transmitter 32 is held at a constant scroll position. The unmodulated signal will indicate to the receiver 36 that the depth measurement can be made more accurately when the unmodulated signal is transmitted. Receiver 36 may also adjust the filter characteristics to change the frequency response for the received signal during transmission of the unmodulated signal.

To improve the reception and detection of signals from transmitter 32, receiver 36 includes two parallel sets of digital signal processing ("DSP") filters 79 (shown in fig. 4) disposed within processor 66. Although a software implemented DSP filter is described herein, the present invention may also be used with hardware implemented filters. The first set of filters 79a preferably comprises wideband filters. The second set of filters 79b preferably comprises narrow band filters. Narrow band filter 79b preferably has a bandwidth of about 10 Hz. The wideband filter 79a preferably has a bandwidth range of 125-200Hz and is used to decode information from the modulated signal and perform calculations for locating the transmitter 32. When transmitter 32 transmits only one carrier signal, the determination of the transmitter location is based only on the output of narrow band filter 79 b. Wideband filter 79a will again be used for position location when transmitter 32 begins communicating and the wideband filter detects the transmitted signal. Wideband filter 79a may be used to verify communications, ignore random noise and recognize sync characters.

Referring now to FIG. 5, there is shown a schematic representation of a display screen assemblyProcessor 66 uses a flow chart of a plurality of DSP filters 79a and 79 b. The signal from transmitter 32 arrives at the filter as shown at 400. The signal is received at 402 by narrowband filter 79b and at 404 by wideband filter 79 a. Narrowband filter 79b updates the positioning data only at 406. Wideband filter 79a updates the positioning data at 408 and decodes the information at 410. If the decoded information is found to be present at 412, then the processor 66 within the receiver 36 recognizes that the positioning data from the wideband filter 79a at 408 should be used at 414. If no corresponding information is found at 412, processor 66 uses the positioning data from narrowband filter 79b at 406 at 414. It will be appreciated by those of ordinary skill in the art that the use of two sets of filters as described herein provides the benefit of removing more signal noise and thus improving the accuracy of the position measurement.

The receiver assembly 36 in the present invention uses the magnetic field measurements from the antenna devices 41 and 42 to directly move the receiver. With appropriate movement, receiver 36 can accurately position transmitter 32 in three-dimensional (3-D) space relative to the receiver. Each antenna device 41 and 42 is capable of obtaining three distinguishable orthogonal magnetic field components at any location. In the preferred embodiment described above, three antennas in each device 41 and 42 provide these magnetic field measurements.

Receiver assembly 36 may be used to locate transmitter 32 in three-dimensional (3-D) space. When in the area of the transmitter 32, the receiver 36 is used to find the transmitter plane (y-axis, where z = 0) by using the flux angle measured at the antennas 41 and 42. When the flux angles at antennas 41 and 42 are both 0, receiver 36 is in the transmitter plane and the position of transmitter 32 relative to the receiver is determined. It will be understood by those of ordinary skill in the art that a flux angle measurement of 0 indicates that the flux angles at antennas 41 and 42 are the same as the inclination of transmitter 32 with respect to the horizontal; indicating that receiver 36 is in the transmitter plane (y-axis, where z = 0). Preferably, the position of the transmitter 32 is determined by the transmitter at the origin of the x-y-z coordinate system. In order to inventFor purposes of (1), the z-axis is designated as the axial direction along the transmitter 32, the y-axis is designated as the horizontal axis perpendicular to the transmitter axial direction, and the x-axis is designated as the vertical axis perpendicular to the transmitter axial direction. Thus, the z-axis is a longitudinal measure, the y-axis is a left-right measure, and the x-axis is a depth measure.

In the preferred embodiment, and particularly where the operator has a general idea of the location of the boring tool 24 and the bore path 12, the receiver 36 is used as follows. The receiver assembly 36 is maintained such that the axis between the antenna devices 41 and 42 is substantially perpendicular to the estimated borehole path 12. Preferably, receiver 36 is maintained in a substantially horizontal plane, although calculations may be used to compensate for any slope of the receiver. More preferably, receiver 36 may be allowed to deviate no more than 20 degrees (20 °) from horizontal. The receiver 36 is then advanced along the estimated borehole path 12 until the flux angle measurements with respect to each of the antennas 41 and 42 are zero (0).

With receiver 36 in the plane of transmitter 32, the position of transmitter 32 relative to the receiver can be determined using the geometric relationships of FIG. 6 and well known equations. Based on the measurements and calculations, for example, the operator may obtain a left-right offset distance of receiver 36 to a position directly above transmitter 32. Receiver 36 may also be moved left and right until the total magnetic field measured by antennas 41 and 42 is equal. When the total magnetic field measured by the antennas 41 and 42 is equal and the flux angle measurement with respect to each antenna 41 and 42 is 0, the receiver 36 is positioned directly above the transmitter (here y = z = 0). Repeated small movements of receiver 36 to ensure that the zero field measurement (magnetic field measurement measured along the x-axis) is 0 and that the total magnetic field measurement is maximized can allow the position of transmitter 32 to be more accurately indicated. When the receiver 36 is positioned directly above the transmitter, an accurate determination of the depth of the transmitter 32 can be made. In the preferred embodiment, the signal status or magnitude of the antennas 41 and 42 is communicated to the operator via the display screen 72. The information of the antennas 41 and 42 may be in digital form or with other imaging techniques such as virtual bubble levelsThe instruments communicate.

As described above, the receiver 36 may contain a sensor 68 responsible for measuring the tilt angle (tilt) or pitch (pitch) of the receiver and capable of calculating β. The calculations may also be used to compensate for the tilt of the transmitter 32. Also, as described above, when the total magnetic field at the antennas 41 and 42 is found to be equal in magnitude, the value of y is 0. However, one of ordinary skill in the art will appreciate that the value of y will still be determined by the geometric relationship if the magnetic field is unbalanced or if receiver 36 is moved slightly in a subsequent step.

The position of receiver 36 relative to transmitter 32 may be obtained by directly solving the magnetic field equations. The magnetic field equations for this system are:

and

wherein 。

Referring to FIG. 7, there is shown And the relationship between the two, we have the following equation:

。

the system of equations may be solved below to determine the position of the transmitter 32 relative to the receiver 36. The signs of y and z can be found to be unstable when solving the equations. However, these symbol instabilities may be discovered by adjusting receiver 36 to determine which antenna arrangement is detecting the largest total magnetic field magnitude. If receiver 36 is adjusted along the z-axis, the magnetic field magnitude readings may be used to determine whether the receiver is in front of or behind transmitter 32. By adjusting receiver 36 along the y-axis, the magnetic field magnitude readings can be used to determine whether the receiver is to the left or right of transmitter 32. This information may be provided to receiver 36 to enable proper calculations. Alternatively, a program using receiver 36 may be disabled to indicate when to hold the receiver on the y-axis or the z-axis to enable the receiver to determine the correct sign of y and z in the system of equations above.

The present invention also includes a new technique for calibrating receiver 36 to transmitter 32 where a calibration constant k is required. Preferably, the receiver support is arranged on the bottom surface such that the axis between the antennas 41 and 42 is perpendicular (in the plane of z = 0) to the axis of the transmitter 32. The distance from the transmitter 32 to the location where the receiver 36 is located need not be specified explicitly. Magnetic field measurements are then made by the antennas 41 and 42. The constant k can be determined for use with the receiver in later measurements using known magnetic field equations and known distances between the antennas.

If the antennas 41 and 42 are both perpendicular to the axis of the transmitter 32 and at a distance L apart, the magnetic field measured at each antenna rod can be written as:

and ，

wherein Is the magnetic field measured at the antenna closest to the transmitter Is the magnetic field measured at the antenna furthest from the transmitter. The distance d from the nearest antenna 41 or 42 to the transmitter 32 can be solved using the following equation:

then by using the magnetic field equation again, the magnetic field equation can be calculated Or K is a constant of.

In an alternative embodiment, the receiver 36 of the present invention may be used to discover the location of the transmitter 32 even if the approximate location of the transmitter or borehole path 12 is unknown. To position the transmitter 32 in this case, the receiver is first rotated in the horizontal plane36 until the received signal strength at each antenna 41 and 42 is the same. The receiver 36 is then rotated 90 deg. and moved in a direction determined by the axis between the antenna devices 41 and 42 until the received signal strength at each antenna 41 and 42 is again the same. In this position, the receiver 36 is generally above the transmitter 32, and the above-described procedure for locating the transmitter when its position and borehole path 12 are generally known can be used to accurately locate the transmitter.

The present invention may be used to identify the precise coordinates of receiver 36 relative to transmitter 32 using the magnetic field measurements from the multiple antenna devices 41 and 42 and the process and equations described above. Information regarding the location of the transmitter 32 is preferably provided to the operator using a visual display screen 72. The method described herein allows the receiver assembly 36 to be used to quickly and accurately position the boring tool assembly 24 and transmitter 32 in a very few steps and with simple calculations.

Referring now to fig. 8, an alternative embodiment for using the present invention is shown. In this alternative embodiment, receiver 36 is designed to be used as the target of the boring tool assembly 24. As shown in fig. 8, receiver 36 is positioned above ground at a target location in front of tool assembly 24. Preferably, the receiver 36 is arranged so that each antenna arrangement 41 and 42 is located on the desired borehole path 12. With the information provided to the operator by receiver 36, the operator may direct tool assembly 24 to drill to or past the location at which the receiver is located or at a location determined by the receiver, such as a location at a particular depth below the receiver. Using receiver 36 as a target may also be used to guide boring tool assembly 24 to a desired location in situations where accurate tracking of the boring path is not possible as the tool assembly travels along a dead reckoning path under an obstacle such as a building, river, or road.

The information provided to the operator preferably includes left/right operation guidance, current depthDegree (x) _c ) A predetermined depth (x) at the target position where receiver 36 is disposed _p ) And horizontal offset distance (z) from the receiver ₀ ) And the like. To determine the left/right direction, the magnetic flux angle of the magnetic field measured by the antennas 41 and 42 may be used. With the information provided to the operator, the operator can direct the working assembly 24 in the direction of the flux angle and the assembly can begin traveling toward the vertical plane containing the receiver and, thus, toward the borehole path 12.

Using the geometry shown in fig. 8, the position of the boring tool assembly 24 within the vertical plane containing the boring path 12 can be calculated and provided to the operator. The location of the boring tool assembly 24 preferably includes the depth (x) of the boring tool assembly _p ) And horizontal offset distance (z) of the drilling tool assembly ₀ ). Preferably, the receiver 36 may assume that the boring tool is located within the vertical plane of the desired boring path 12, making the calculation simpler and within a reasonable accuracy. The following formula may be used to provide the required information:

the following steps are utilized: to solve for the problem of theta,

wherein The calculation is performed as an arctangent function of the signal strengths of the antennas 41 and 42. (rotation due to inclination of emitter 32 and rotation of receiver 36)

Current depth:

the predetermined depth is:

horizontal offset: 。

with both antennas 41 and 42 available, the receiver 36 may visually provide the operator with an indication of the progress of the boring tool assembly 24 toward and ultimately away from the receiver. In the preferred embodiment, the information is displayed graphically on the display screen 72. Referring now to FIG. 9, a schematic diagram of a preferred embodiment of a display screen 72 of receiver 36 is shown. The display screen 72 includes a solid horizontal line 80 that forms a portion of a cross-hair on the display screen to indicate a predetermined depth of the transmitter 32 when the transmitter or boring tool assembly 24 reaches the target location. The horizontal dashed line 82 represents the current depth of the emitter 32. Dashed vertical line 84 represents the horizontal offset of transmitter 32 from receiver 36. The left/right direction and size are indicated by the proportional arrow 86 along the middle portion of the cross-hair, if desired. Other status information such as the pitch, roll position, and battery status of the transmitter 32, the temperature of the tool assembly 24, and the battery status of the receiver 36 may also be provided as operator information and used.

Various modifications may be made in the design and operation of the present invention without departing from the spirit thereof. Thus, while the principal preferred construction and modes of operation of the invention have been described in what is presently considered to represent the best modes of carrying out the invention, it is to be understood that the appended claims are entitled to protectionWithin the scope of this disclosure, the invention may be practiced otherwise than as specifically illustrated and described.

Claims (10)

1. A three-dimensional antenna, comprising:

a support structure comprising a first panel, a second panel, and a third panel;

a first coil supported in the first panel and defining an apertured region;

a second coil supported in the second panel and defining an apertured area;

a third coil supported in the third panel and defining an apertured area;

wherein the void area of each of said coils is the same; and is

Wherein the coils have a common center point.

2. The three-dimensional antenna of claim 1, wherein each of three of the panels are oriented orthogonally to each other and each of the panels includes a generally rectangular perforated area.

3. The three-dimensional antenna of claim 1, wherein the support structure comprises a lightweight plastic.

4. The three-dimensional antenna of claim 3, wherein the support structure comprises a first portion and a second portion, and

the first portion is secured to the second portion.

5. The three-dimensional antenna of claim 1, wherein each coil comprises a magnet wire.

6. The three-dimensional antenna of claim 1, wherein the coils do not intersect each other.

7. A three-dimensional antenna, comprising:

a support structure;

a first antenna coil supported in the first panel and defining an apertured region;

a second antenna coil supported in the second panel and defining an apertured region;

a third antenna coil supported in the third panel and defining an apertured area;

wherein the vacant area of each of the antenna coils is the same; and is

Wherein the coils have a common center point.

8. The three-dimensional antenna of claim 7, wherein the support structure defines a first panel, a second panel, and a third panel, an

Wherein the first antenna coil is supported in the first panel;

wherein the second antenna coil is supported in the second panel;

wherein the third antenna coil is supported in the third panel.

9. The three-dimensional antenna of claim 8, wherein each of three of the panels is oriented orthogonally to each other.

10. The three-dimensional antenna of claim 7, wherein the apertured area of each antenna coil is a rectangle having rounded corners.