Pipe proximity warning device for accidental damage prevention mounted on the bucket of a backhoe

• US 5,592,092 A
• Filed: 10/28/1994
• Issued: 01/07/1997
• Est. Priority Date: 10/28/1994
• Status: Expired due to Fees

• Current Assignee: Gas Research Institute (GTI Energy)
• Original Assignee: Gas Research Institute (GTI Energy)
• Inventors: Mechler, Mark V.
• Primary Examiner(s): O'Shea, Sandra L.
• Assistant Examiner(s): PHILLIPS, ROGER
• Application Number:
  US08/331,229
• Time in Patent Office: 802 Days
• Field of Search: 324/66, 324/67, 324/326, 324/329, 324/262, 324/260, 364/560, 364/561, 414/694
• US Class Current: 324/326
• CPC Class Codes: E02F 9/245 for preventing damage to underground objects during excavation, e.g. indicating buried pipes or the like detection of pipes in the ground F16L1/11
• CPC Class Codes: G01V 3/081 the magnetic field is produced by the objects or geological structures characterised by the method of magnetic field measurement G01R33/00

Abstract

A pipe proximity warning device is operable for both cross-line and in-line digging operations to provide a warning to an operator that the bucket of a backhoe is in close proximity to a trace wire on a plastic pipe. The in-line system comprises two sensors located on the bottom of the bucket for detecting a signal on the trace wire. The distance to the wire is determined based upon a ratio of the signals detected by the two sensors. The cross-line system also has two sensors and also employs a ranging system that disables a geometry tracker when the bucket is outside an operable range of distances to the trace wire. From the angles of the boom, stick, and bucket, the geometry tracker determines the horizontal distance x and vertical distance z to the trace wire, both of which may be displayed to an operator in real-time. The sensors for both the cross-line and in-line cases are mounted within a housing that maximizes the sensitivity of the sensors to the signals from the wire and which isolates the sensors from shielding effects of the bucket and from eddy currents on the bucket.

Claims

1. A locating system for use with a backhoe operating in the vicinity of a wire generating a magnetic field for locating the wire and for preventing the wire from becoming damaged, comprising:

a first sensor mounted on a bucket of said backhoe for detecting said magnetic field and for producing a first sensor output signal;

a second sensor mounted on said bucket of said backhoe a predetermined distance from said first sensor for detecting said magnetic field and for producing a second sensor output signal;

processing means for locating said wire by receiving said first sensor output signal and said second sensor output signal and determining the distance from said backhoe to said wire, wherein said processing means receives a signal representing an angle of said bucket and determines said distance to said wire based upon the following equation;

space="preserve" listing-type="equation">z=γ

σ

.sup.2 +β

σ

+α

where σ

is the ratio of said first sensor output signal to said second sensor output signal and α

, β

, and γ

are constants unique for the bucket angle; and

means for indicating said distance and direction from said backhoe to said wire.

2. The system as set forth in claim 1, wherein said indicating means comprises a depth display for indicating a depth of said wire.

3. The system as set forth in claim 1, further comprising means for disabling said backhoe when said backhoe comes within a predetermined distance to said wire.

4. The system as set forth in claim 1, wherein said first sensor and said second sensor are aligned to detect said field from said wire when said backhoe is performing an in-line digging operation.

5. The apparatus as set forth in claim 1, wherein said first sensor and said second sensor each comprise:

a core material;

a plurality of turns of wire wrapped around said core material; and

a sensor housing, said sensor housing comprising;

a lower housing portion forming a bottom wall of said sensor housing and having four side walls; and

an upper housing portion forming a top wall of said sensor housing and having four side walls, said four side walls of said upper housing portion mating with said four side walls of said lower housing portion to form four side walls of said sensor housing;

said sensor housing being fabricated from a material having a permeability approximately equal to 1.0 and wherein said upper housing portion is insulated from said lower housing portion.

6. The apparatus as set forth in claim 1, wherein said first sensor and said second sensor are aligned to detect said field from said wire when said backhoe is performing a cross-line digging operation.

7. The apparatus as set forth in claim 6, wherein said second sensor comprises:

a plastic bobbin;

a plurality of turns of wire wrapped about said plastic bobbin;

a core material inserted within a center of said plastic bobbin; and

a sensor housing for enclosing said plastic bobbin, said turns of wire, and said core material;

wherein said sensor housing is fabricated from a material having a permeability approximately equal to 1.0.

8. The apparatus as set forth in claim 6, further comprising means for tracking said distance to said field generating device based upon said first sensor output signal, said second sensor output signal, an angle of a bucket of said backhoe, an angle of a boom of said backhoe, and an angle of a stick of said backhoe.

9. The apparatus as set forth in claim 8, further comprising a ranging system for disabling said tracking means when said bucket is outside a certain distance to said field generating device.

10. The apparatus as set forth in claim 1, wherein said processing means comprises:

an inclinometer mounted to said bucket for generating a pulsed output signal having a pulse width proportional to an angle of said bucket;

means for generating a clock signal; and

means for counting pulses from said clock signal during said pulsed output signal and for producing a digital signal representing said bucket angle.

11. The apparatus as set forth in claim 10, further comprising a second inclinometer for a boom of said backhoe and a third inclinometer for a stick of said backhoe.

12. The apparatus as set forth in claim 10, further comprising a memory receiving said digital signal and producing a first signal representing said angle at a first timing, a second signal representing said angle multiplied by a first sinusoidal value at a second timing, and a third signal representing said angle multiplied by a second sinusoidal value at a third timing.

13. The apparatus as set forth in claim 1, further comprising a peak detector for determining said distance from said backhoe to said wire.

14. The apparatus as set forth in claim 5, wherein said sensor core material comprises ferrite.

15. The apparatus as set forth in claim 5, wherein said sensor core material and said turns of wire are encapsulated within silicon rubber.

16. The apparatus as set forth in claim 5, wherein a flange is formed on each of two side walls of said upper housing portion which are opposite each other and which are parallel to flux lines generated by a field generating device.

17. The system as set forth in claim 1, wherein said processing means comprises a memory for storing values of said constants α

, β

, and γ

for a range of values of the bucket angle.

18. A method for determining a location of a wire generating a magnetic field by determining a distance from a backhoe to a wire for preventing said wire from becoming damaged, comprising the steps of:

detecting at a first location on a bucket of said backhoe a field generated by said wire and producing a first sensor output signal;

detecting at a second location on said bucket of said backhoe a field generated by said wire and producing a second sensor output signal;

using processing means to receive a signal representing an angle of the bucket and determining said distance from the backhoe to said wire based upon the ratio σ

of said first sensor output signal to said second sensor output signal and the angle of the backhoe, using the equation z=γ

σ

² +β

σ

+α

where α

, β and

γ

are constants unique for the bucket angle.

19. The method as set forth in claim 18, further comprising the step of disabling said object when said distance from said object to said field generating device is less than a predetermined distance.

20. The method as set forth in claim 18, further comprising the step of displaying a depth of said object.

21. The method as set forth in claim 18, wherein said object comprises a backhoe and said method further comprises the steps of receiving a first angle signal representing an angle of a bucket of the backhoe, receiving a second angle signal representing an angle of a stick of the backhoe, and receiving a third angle signal representing an angle of a boom of the backhoe.

22. A locating system for use with a backhoe operated in the vicinity of a device which generates a field for locating the field generating device and for preventing said field generating device from becoming damaged, comprising:

a first sensor mounted on the backhoe for detecting said field generated by said field generating device and for producing a first sensor output signal;

a second sensor mounted on said backhoe a predetermined distance from said first sensor for detecting said field from said field generating device and for producing a second sensor output signal;

wherein said first sensor and said second sensor are aligned to detect said field from said field generating device when said backhoe is performing a cross-line digging operation;

processing means for locating said field generating device by receiving said first sensor output signal and said second sensor output signal and determining the distance from the backhoe to said field generating device based upon the ratio of said first sensor output signal to said second sensor output signal;

means for indicating said distance from said backhoe to said field generating device;

means for tracking said distance to said field generating device based upon said first sensor output signal, said second sensor output signal, an angle of a bucket of said backhoe, an angle of a boom of said backhoe, and an angle of a stick of said backhoe;

a ranging system for disabling said tracking means when said bucket is outside a certain distance to said field generating device.

23. A locating system for use with a backhoe operating in the vicinity of a wire generating a magnetic field for locating the wire and for preventing said wire from becoming damaged, comprising:

a first sensor mounted on a bucket of said backhoe for detecting said field generated by said wire and for producing a first sensor output signal;

a second sensor mounted on said bucket of said backhoe a predetermined distance from said first sensor for detecting said field from said wire and for producing a second sensor output signal;

processing means for locating said wire by receiving said first sensor output signal and said second sensor output signal and determining the distance from the backhoe to said wire based upon a ratio of said first sensor output signal to said second sensor output signal, said processing means comprising an inclinometer mounted to said bucket for generating a pulsed output signal having a pulse width proportional to an angle of said bucket, means for generating a clock signal, and means for counting pulses from said clock signal during said pulsed output signal and for producing a digital signal representing said bucket angle; and

means for indicating said distance and direction from said backhoe to said wire.

24. The system as set forth in claim 23, further comprising a second inclinometer for a boom of said backhoe and a third inclinometer for a stick of said backhoe.

25. The system as set forth in claim 23, further comprising a memory receiving said digital signal and producing a first signal representing said angle at a first timing, a second signal representing said angle multiplied by a first sinusoidal value at a second timing, and a third signal representing said angle multiplied by a second sinusoidal value at a third timing.