Detecting underground conductors

• US 20020047709A1
• Filed: 08/17/2001
• Published: 04/25/2002
• Est. Priority Date: 04/28/1999
• Status: Active Grant

• Current Assignee: Fling, Richard William
• Original Assignee: Fling, Richard William
• Inventors: Fling, Richard William
• Granted Patent: US 6,633,163 B2
• Time in Patent Office: Days
• 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 construction vehicle, the vehicle having a plurality of sensors, each sensor having at least one detector arranged to detect a magnetic field component which is generally parallel to the ground on which the vehicle stands or moves, the sensor being for detecting a magnetic field generated by a current in buried conductors, the sensors being at different heights on the vehicle relative to the ground;

there being means for comparing the magnitudes of the magnetic field detected by the sensors.

2. A vehicle according to claim 1, wherein each detector is a solenoid with a generally horizontal axis.

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

4. A vehicle according to claim 1, having amplifiers for amplifying the outputs of the sensors prior to the comparison by the comparison means, the amplifiers being of variable gains.

5. A vehicle according to claim 1, wherein each sensor has an adjustable detection threshold.

6. A vehicle according to claim 5, wherein the detectors threshold of at least one of said sensors is different from the detections threshold of least one other of said sensors.

7. A vehicle according to claim 1, wherein the sensors are arranged to be sensitive to magnetic fields of at least one predetermined frequency.

8. A vehicle according to claim 7, wherein at least one of said sensors is arranged to be sensitive to magnetic fields of a first predetermined frequency and at least one other of said sensors is arranged to be sensitive to magnetic fields of a second predetermined frequency.

9. A vehicle according to claim 1, wherein the sensors are arranged to be sensitive to a magnetic field of a plurality of different frequency bands.

10. A vehicle according to claim 9, wherein said means for comparing is arranged to compare the outputs of the sensors at different times for different frequency bands.

11. A vehicle according to claim 9, wherein for at least one frequency band said means for comparing is arranged to compare simultaneously the outputs of the sensors for said at least one frequency band.

12. A vehicle according to claim 9, wherein the detection threshold of said sensors for one of said frequency bands is different from the detection threshold of said sensors for another and of said frequency bands.

13. A vehicle according to claim 9, wherein the sensors each include a DSP for determining said frequency bands.

14. An excavation vehicle according to claim 1, wherein each sensor has at least two orthogonal coils, which coils are generally horizontal.

15. An excavation vehicle according to claim 1, wherein the sensors are adjusted to detect magnetic fields at a plurality of selected frequencies.

17. A method according to claim 16, further including generating an indication when the magnitude of the magnetic field detected by a higher sensor is less than the magnitude of a lower sensor.

19. A vehicle according to claim 18 wherein each sensor has a coil with an axis generally parallel to the ground.

20. A vehicle according to claim 18, wherein the comparison means has a variable sensitivity.

21. A vehicle according to claim 18, comprising variable gain amplifiers for amplifying the outputs of said upper and lower sensor means.

22. A vehicle according to claim 18, wherein each sensor has an adjustable detection threshold.

23. A vehicle according to claim 22, wherein the detectors threshold of at least one of said sensors is different from the detections threshold of least one other of said sensors.

24. A vehicle according to claim 18, wherein the sensors are arranged to be sensitive to magnetic fields of a predetermined frequency.

25. A vehicle according to claim 24, wherein at least one of said sensors is arranged to be sensitive to magnetic fields of a first predetermined frequency and at least one other of said sensors is arranged to be sensitive to magnetic fields of a second predetermined frequency.

26. A vehicle according to claim 18, wherein the sensors are arranged to sensitive to a magnetic field of a plurality of different frequency bands.

27. A vehicle according to claim 26, wherein said means for comparing is arranged to compare the outputs of the sensors at different times for each frequency band.

28. A vehicle according to claim 26, wherein said means for comparing is arranged to compare simultaneously the outputs of the sensors for at least one frequency band.

29. A vehicle according to claim 26, wherein the detection threshold of said sensors for one of said frequency bands is different from the detection threshold of said sensors for another and of said frequency bands.

30. A vehicle according to claim 26, wherein the sensors each include a DSP for determining said frequency bands.

16. A method of detecting an underground conductor, using sensors mounted at different heights on an construction vehicle, which sensors each have at least one detector which is arranged to detect a magnetic field component which is generally parallel to the ground, the method comprising:

causing a current to flow in the underground conductor, so as to generate a magnetic field;

detecting the magnetic field using the sensors; and

comparing the magnitudes of the magnetic field detected by the sensors;

thereby to determine the relationship between the position of the underground conductor and the position of the vehicle.

18. An excavation vehicle having forward and rearward portions along a line of forward movement along the surface of the ground, said vehicle comprising:

an excavating means along the rearward portion of said vehicle for insertion into said surface of said ground to a predetermined depth below said surface;

upper and lower sensor means mounted along the forward portion of said vehicle to define a protection zone relative to said vehicle forward of said excavating means, each of a said sensor means having at least one detector means for detecting a component of a magnetic field severally parallel to the ground and thereby detecting an electrical current in buried conductors located below said surface of said ground;

said sensor means being located at different distances from said surface of said ground;

comparison means for comparing the magnitude of the detected currents to provide a signal indicative of the presence of a buried conductor in said protective zone; and

indicator means for producing a given signal when said processing means indicates the presence of said buried conductor within said protective zone.