System and method for detecting, localizing, or classifying a disturbance using a waveguide sensor system

• US 20030020610A1
• Filed: 05/02/2002
• Published: 01/30/2003
• Est. Priority Date: 05/02/2001
• Status: Active Grant

• Current Assignee: Penn State Research Foundation
• Original Assignee: Penn State Research Foundation
• Inventors: Nicholas, Nicholas C., Rigsby, David, Swanson, David C.
• Granted Patent: US 6,731,210 B2
• Time in Patent Office: Days
• US Class Current: 340/566
• CPC Class Codes: G08B 13/122 for a perimeter fence features peculiar to electrified fences A01K3/00
• CPC Class Codes: G08B 13/1609 using active vibration detection systems

Abstract

A vibration detection and classification system and associated methods are disclosed. The system includes a waveguide in operative contact with a boundary, such as a security fence. At least one sensor for sensing vibrations such as acoustic waves is operatively connected to the waveguide, the waveguide extending the range of the sensor. At least one control circuit is operatively connected to the one or more sensors and is adapted for detecting and classifying vibrations. The method includes securing an area protected by a boundary by mechanically transmitting a vibration from a portion of the boundary to a waveguide, transmitting the vibration along the waveguide to a sensor, sensing the vibration at the sensor, determining at least one characteristic associated with the vibration, and using the at least one characteristic associated with the vibration to determine if the vibration is indicative of an intrusion.

Claims

1. A vibration detection and classification system, comprising:

a waveguide in operative contact with a boundary;

at least one sensor for sensing vibrations operatively connected to the waveguide, the waveguide extending the range of the sensor;

a control circuit operatively connected to the at least one sensor and adapted for detecting and classifying vibrations.

2. The vibration detection and classification system of claim 1 wherein the control circuit is further adapted for detecting and classifying vibrations to determine if the boundary has been crossed by an intruder.

3. The vibration detection and classification system of claim 1 wherein the vibrations are acoustic waves.

4. The vibration detection and classification system of claim 1 further comprising at least one vibration coupler for coupling the waveguide to the boundary.

5. The vibration detection and classification system of claim 1 wherein the boundary includes a fence.

6. The vibration detection and classification system of claim 5 further comprising a vibration coupler operatively connected between the waveguide and the fence.

7. The vibration detection and classification system of claim 1 wherein the vibration coupler is a thick arc-shaped band of metal.

8. The vibration detection and classification system of claim 1 wherein the waveguide is tensioned wire.

9. The vibration detection and classification system of claim 8 wherein the tension of the wire is between 50 to 200 pounds.

10. The vibration detection and classification system of claim 8 wherein the mass and tension of the wire are selected to match a natural frequency and wave speed of the fence.

11. The vibration detection and classification system of claim 8 wherein tension is applied to the tensioned wire using at least one mass and at least one pulley.

12. The vibration detection and classification system of claim 11 wherein the control circuit is adapted for localization of one or more intrusions by using a loudness ratio.

13. The vibration detection and classification system of claim 1 wherein the waveguide is a pipe filled with a fluid and the wave is an acoustic wave.

14. The vibration detection and classification system of claim 1 wherein each of the control circuits includes a transceiver, the transceiver adapted for transmitting a vibrational wave through the waveguide and receiving vibrational waves transmitted through the waveguide.

15. The vibration detection and classification system of claim 14 wherein each of the transceivers includes a clock.

16. The vibration detection and classification system of claim 15 wherein there are at least two transceivers, each transceiver having a clock, each of the clocks synchronized to a time base.

17. The vibration detection and classification system of claim 16 wherein the time base is derived from a GPS signal.

18. The vibration detection and classification system of claim 1 wherein the control circuit is adapted to determine when a sensed vibration signal exceeds a threshold.

19. The vibration detection and classification system of claim 15 wherein the threshold is partially based on an average background noise signal.

20. The vibration detection and classification system of claim 1 wherein the control circuit is adapted to process a long-term average vibration signal and a short term average vibration signal and to determine when the short term average vibration signal exceeds a threshold.

21. The vibration detection and classification system of claim 20 wherein the threshold is at least partially based on the long-term average vibration signal.

22. The vibration detection and classification system of claim 1 wherein the control circuit includes a constant false alarm rate detector.

23. The vibration detection and classification system of claim 1 further comprising an alarm circuit operatively connected to the control circuit.

24. The vibration detection and classification system of claim 1 wherein the control circuit is adapted to determine a location along the boundary associated with a sensed vibration.

25. The vibration detection and classification system of claim 24 wherein the control circuit is adapted to determine the location based on a time delay estimation.

26. The vibration detection and classification system of claim 24 wherein the control circuit is adapted to determine the location based on a loudness ratio.

27. The vibration detection and classification system of claim 26 wherein the loudness is converted to an angle via an arctangent.

28. The vibration detection and classification system of claim 24 wherein the control circuit is adapted to determine the location based on a time delay estimation and a loudness ratio.

29. The vibration detection and classification system of claim 1 wherein the control circuit is adapted to resolve both compressional waves and string waves.

30. The vibration detection and classification system of claim 1 wherein the control circuit is adapted to separate waves by direction

31. The vibration detection and classification system of claim 1 wherein the control circuit is adapted to separate waves by speed.

32. The vibration detection and classification system of claim 1 wherein at least two sensors are used to form an array and wherein the control circuit is adapted to determine one or more characteristics of a wave using the array.

33. The vibration detection and classification system of claim 32 wherein the one or more characteristics of the wave include a direction of the wave.

34. The vibration detection and classification system of claim 32 wherein the one or more characteristics of the wave include a speed of the wave.

35. The vibration detection and classification system of claim 32 wherein the array includes three or more sensors.

36. The vibration detection and classification system of claim 32 wherein the array includes at least five sensors and wherein the control circuit is adapted to resolve both compressional waves and string waves and directions associated with the compressional waves and string waves.

37. The vibration detection and classification system of claim 1 further comprising at least one vibration generator operatively connected to the wave guide.

38. The vibration detection and classification system of claim 37 wherein the vibration generator is operatively connected to the control circuit.

39. The vibration detection and classification system of claim 38 wherein the control circuit is adapted for automatic calibration.

40. A method of securing an area protected by a boundary, comprising:

mechanically transmitting a vibration from a portion of the boundary to a waveguide;

transmitting the vibration along the waveguide to a sensor;

sensing the vibration at the sensor; and

determining at least one characteristic associated with the vibration;

using the at least one characteristic associated with the vibration to determine if the vibration is indicative of an intrusion.

41. The method of claim 40 wherein the step of mechanically transmitting the vibration to the waveguide is mechanically transmitting the vibration through a vibration coupler connected between a fence defining the boundary and the waveguide.

42. The method of claim 41 wherein the waveguide is a tensioned wire.

43. The method of claim 40 wherein the at least one characteristic associated with the vibration includes an average RMS signal over a time period.

44. The method of claim 40 wherein the at least one characteristic associated with the vibration includes a time delay associated with the vibration.

45. The method of claim 40 wherein the at least one characteristic associated with the vibration includes a location associated with the vibration.

46. The method of claim 40 wherein the at least one characteristic associated with the vibration includes a loudness.

47. The method of claim 40 further comprising activating an alarm based on a detection of an intrusion.

48. The method of claim 40 further comprising providing an alert based on a detection of an intrusion.

49. A method of monitoring a fence, comprising:

attaching a vibration coupler between a tensioned wire and the fence;

mechanically transmitting a vibration from a portion of the boundary to the tensioned wire;

transmitting the vibration along the tensioned wire to a first sensor located remotely from the vibration coupler;

sensing the vibration at the first sensor; and

determining if the vibration is indicative of a condition.

50. The method of claim 49 wherein the condition is an intrusion.

51. The method of claim 49 further comprising transmitting the vibration along the tensioned wire to a second sensor located remotely from the vibration coupler and sensing the vibration at the second sensor.

52. The method of claim 51 further comprising determining a first time of sensing associated with the first sensor and a second time of sensing associated with the second sensor and determining a difference between the first time and the second time.

53. The method of claim 52 further comprising determining a location associated with a source of the vibration using the difference between the first time and the second time.

55. A method of securing an area protected by a boundary, comprising:

mechanically transmitting a vibration from a portion of the boundary to a waveguide;

transmitting the vibration along the waveguide to a sensor;

sensing the vibration with a plurality of sensors within an array; and

determining at least one characteristic associated with the vibration;

using the at least one characteristic associated with the vibration to determine if the vibration is indicative of an intrusion.