Apparatus and method for detecting an underground cable while operating a piece of machinery

• US 6,633,163 B2
• Filed: 08/17/2001
• Issued: 10/14/2003
• Est. Priority Date: 04/28/1999
• Status: Expired due to Fees

• Current Assignee: Radiodetection Limited
• Original Assignee: Radiodetection Limited
• Inventors: Fling, Richard William
• Primary Examiner(s): PATIDAR, JAY M
• Application Number:
  US09/931,994
• Publication Number:
  US 20020047709A1
• Time in Patent Office: 788 Days
• Field of Search: 324/67, 324/326-329, 324/242, 324/243, 324/207.26, 324/207.15, 324/247, 379/06
• US Class Current: 324/326
• CPC Class Codes: G01V 3/104 using several coupled or uncoupled coils G01V3/101 takes precedence
• CPC Class Codes: G01V 3/15 specially adapted for use during transport, e.g. by a person, vehicle or boat

Abstract

An excavator vehicle has sensors thereon at different heights. Each sensor may have a coil which is generally horizontal and which detects the magnetic field generated by a current in a buried conductor. By detecting the relative magnitudes of the component of the field parallel to the ground, as detected by the sensors, it is possible to determine whether or not the excavator vehicle is proximate the buried conductor. A warning may be generated, or the excavating tool of the excavator vehicle controlled, to prevent the excavating tool damaging the buried conductor.

Claims

1. A vehicle having forward and rearward portions along a line of forward movement along the surface of the ground, the vehicle comprising:

means for an excavating along the rearward portion of the vehicle for insertion into the surface;

upper and lower means for sensing mounted along the forward portion of the vehicle to define a protection zone relative to the vehicle, the upper and lower means for sensing are located forward and at the opposing end from the excavating means and at differing distances from the surface of the ground, the upper and lower means for sensing comprise at least one detector means for detecting a component of a magnetic field generally parallel to the ground produced by an underground conductor;

means for comparing the magnitude of the magnetic fields detected by the upper and lower and means for sensing to determine the presence of the underground conductor in the protective zone; and

means for indicating that the underground conductor has been detected in the protective zone.

2. The vehicle according to claim 1, wherein the upper and lower means for sensing comprise a coil with an axis is generally parallel to the surface.

3. The vehicle according to claim 1, wherein the means for comparing has a variable sensitivity.

4. The vehicle according to claim 1, further comprising variable gain amplifiers linked to the upper and lower means for sensing.

5. The vehicle according to claim 1, wherein the upper and lower means for sensing further comprise an adjustor to adjust the detection threshold of each upper and lower means for sensing.

6. The vehicle according to claim 5, wherein the detection threshold of at least one of the upper or lower means for sensing if different from the detection of at least one other of the upper or lower means for sensing.

7. The vehicle according to claim 1, wherein the upper or lower means for sensing are configured such that they are sensitive to magnetic field of a predetermined frequency.

8. The vehicle according to claim 7, wherein at least one of the upper or lower means for sensing is configured to be sensitive to magnetic fields of a first predetermined frequency and at least the other of the upper or lower means for sensing is arranged to be sensitive to magnetic fields of a second predetermined frequency.

9. The vehicle according to claim 1, wherein the upper and lower means for sensing are configured to be sensitive to a magnetic field having a plurality of different frequency bands.

10. The vehicle according to claim 9, wherein the means for comparing is configured to compare the outputs of the upper and lowers means for sensing at different times for each frequency band.

11. The vehicle according to claim 9, wherein the means for comparing is configured to simultaneously compare the outputs of the sensor for at least one frequency band.

12. The vehicle according to claim 1, wherein the upper and lower means for sensing has an adjustor to adjust its detection threshold, and the detection threshold of the upper and lower means for sensing for one of the frequency bands is different from the detection threshold of the upper and lower means for sensing for another of the frequency bands.

13. The vehicle according to claim 1, wherein the upper and lower means for sensing each include a digital signal processor for determining frequency bands.

14. A excavation machine having a forward and rearward portion along a line of forward movement along the surface of a ground, the vehicle comprising:

an excavator along the rearward portion of the vehicle to be inserted into the ground;

upper and lower sensors mounted along the forward portion of the excavation machine and at the opposing end of the excavator to define a protection zone, the sensor are positioned at differing distances from the ground, each of the sensors comprising at least one detector to detect a component of a magnetic field generally parallel to the ground generated by a underground conductor;

a processor linked to the sensors to determine whether the underground cable is located within the protection zone; and

an indicator connected to the processor that is activated once the underground cable is located within the protection zone.