Method for detecting acoustic emission using a microwave doppler radar detector

• US 20050265124A1
• Filed: 04/22/2005
• Published: 12/01/2005
• Est. Priority Date: 04/22/2004
• Status: Active Grant

• Current Assignee: Gregory Carlyle Smith
• Original Assignee: Gregory Carlyle Smith
• Inventors: Smith, Gregory C.
• Granted Patent: US 7,397,421 B2
• Time in Patent Office: Days
• US Class Current: 367/128
• CPC Class Codes: B23Q 17/098 by measuring noise
• CPC Class Codes: G01S 13/524 based upon the phase or frequency shift resulting from movement of objects, with reference to the transmitted signals, e.g. coherent MTi
• CPC Class Codes: G01S 13/88 Radar or analogous systems specially adapted for specific applications electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00

Abstract

Acoustic emissions are detected by reflecting microwave radar signals off of an object, receiving reflected radar signals, generating an intermediate frequency, and filtering the intermediate frequency to remove low frequency signals associated with object movement and not acoustic emissions. A microwave Doppler radar detector provides the signals, a band-pass filter filters the intermediate frequency signal, and resulting signal is collected and analyzed to establish a relationship between the acoustic emission and the filtered signal. One application described is detecting tool wear using a microwave Doppler-based acoustic emission sensor and predicting tool wear based on the detected acoustic emission.

Claims

1. A method of detecting acoustic emissions comprising:

flooding an area with a transmitted microwave radar signal;

receiving reflected radar signal from the flooded area;

generating an intermediate frequency signal based on differences between said microwave radar signal and said reflected radar signal;

filtering said intermediate frequency signal to isolate signals associated with acoustic emissions, remove low-frequency signals of less than approximately 1 kHz associated with mechanical motion; and

measuring the filtered intermediate frequency signal.

2. The method of claim 1, wherein said microwave signal is generated by a microwave transmitter and said reflected radar signal are received by a microwave receiver.

3. The method of claim 2, wherein a Doppler radar detector houses said microwave transmitter, houses said microwave receiver, and provides said intermediate frequency signal.

4. The method of claim 1, wherein a band-pass filter performs said filtering.

5. The method of claim 4, wherein said band-pass filter further removes high-frequency signals sufficient to prevent aliasing and said filtered IF signal is provided to a computer for signal sampling, digital signal processing, and signal analysis.

6. The method of claim 1, wherein said method further includes determining a characteristic associated with said area at least partially based on said filtered intermediate frequency signal.

7. The method of claim 6, wherein said characteristic is based on the amplitude of said relfected radar signal.

8. The method of claim 6, wherein said characteristic is based on the frequency of said relfected radar signal.

9. The method of claim 6 wherein said area includes at least one object that is dielectric or metallic, said reflected radar reflections are reflected off of said at least one object, and said characteristic is associated with said at least one object.

10. The method of claim 9, wherein said at least one object is a tool and said characteristic is wear of said tool.

11. The method of claim 10, wherein said tool is a lathe.

12. A method of detecting acoustic emissions comprising:

flooding an area with a transmitted microwave radar signal;

receiving reflected radar signal from the flooded area;

generating an intermediate frequency signal based on differences between said transmitted microwave radar signal and said reflected radar signal;

filtering said intermediate frequency signal to isolate signals associated with acoustic emissions, remove low-frequency signals of less than 1 kHz associated with mechanical motion, and remove high-frequency signals sufficient to prevent aliasing;

measuring the filtered intermediate frequency signal;

determining a characteristic associated with said area at least partially based on said filtered intermediate frequency signal; and

establishing a relationship between said characteristic and said filtered intermediate frequency signal to allow prediction of said characteristic based upon said filtered intermediate frequency signal.

13. The method of claim 12, wherein a Doppler radar detector houses a microwave transmitter that generates said transmitted microwave signal, houses a microwave receiver that receives said radar reflections, and provides said intermediate frequency signal.

14. The method of claim 12, wherein a band-pass filter performs said filtering.

15. The method of claim 12, wherein said characteristic is based on the amplitude of said reflected radar signal.

16. The method of claim 12, wherein said characteristic is based on the frequency of said reflected radar signal.

17. The method of claim 12, wherein said relationship is a regression relationship.

18. The method of claim 12 wherein said area includes at least one object that is dielectric or metallic, said reflected radar reflections are reflected off of said at least one object, and said characteristic is associated with said at least one object.

19. The method of claim 18, wherein said at least one object is a tool and said characteristic is wear of said tool.

20. The method of claim 19, wherein said tool is a lathe and tool wear is predicted during operation of said lathe.