System and method for determining and detecting stability loss in structures

• US 20080059086A1
• Filed: 04/21/2007
• Published: 03/06/2008
• Est. Priority Date: 02/21/2002
• Status: Abandoned Application

• Current Assignee: Sekos, Inc.
• Original Assignee: Sekos, Inc.
• Inventors: Nielsen, Gregory, Lupei, Zach, Schilling, Casey, Duron, Ziyad, Pranger, Loland
• Application Number:
  US11/788,751
• Publication Number:
  US 20080059086A1
• Time in Patent Office: Days
• US Class Current: 702/56
• CPC Class Codes: G01N 29/12 by measuring frequency or resonance of acoustic waves measuring frequency or resonant frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04, G01H13/00; acoustic resonators G10K11/04; vibration or shock testing of structures G01M7/00
• CPC Class Codes: G01N 29/223 Supports, positioning or alignment in fixed situation mounting transducers per se G10K11/004
• CPC Class Codes: G01N 29/44 Processing the detected response signal , e.g. electronic circuits specially adapted therefor digital signal processing per se G06F17/00
• CPC Class Codes: G01N 29/46 by spectral analysis, e.g. Fourier analysis or wavelet analysis spectral signal processing per se G06F17/14

Abstract

A significant number of rescue workers are killed or injured each year as they conduct searches within damaged or burning structures, unaware that the structure is unstable. The present invention provides a system and method for real-time detecting and monitoring structural instability that may lead to inevitable collapse of a structure. The system is capable of displaying data, including visual and/or audible signals, indicating structural instability. Additionally, the present invention is also directed to stability monitoring analysis processes for determining structural stability or instability.

Claims

1. A method for determining stability of a structure comprising:

utilizing a real-time system structural stability monitoring system based upon Frequency Based Indicator Analysis said Frequency Based Indicator Analysis having at least one of a Wavelet Transform Analysis, an Empirical Mode Decomposition Analysis and an Instantaneous Frequency Analysis.

2. A method as recited in claim 1 and further comprising the steps of:

(a) utilizing a thermally protected mounting plate and attaching a stability monitoring device of said system to said structure;

(b) obtaining an amplified signal from said system;

(c) filtering and removing signal noise from said signal; and

(d) obtaining a filtered signal.

3. A method as recited in claim 2, wherein said filtering step further comprises locating frequencies to be utilized by said Analysis.

4. A method as recited in claim 3, wherein said Frequency Based Indicator Analysis further comprises determining changes in transient responses of said structure and lost stability of said structure over time.

5. A method as recited in claim 4, wherein said Frequency Based Indicator Analysis further comprises obtaining dominant frequency tracking utilizing said Wavelet Transform Analysis, obtaining average instantaneous frequency tracking of separated modes utilizing said Empirical Mode Decomposition and said Instantaneous Frequency Tracking.

6. A method as recited in claim 5 and further comprising verifying said Frequency Based Indicator Analysis by passing a signal through a bank of band pass filters.

7. A method as recited in claim 6, and further comprising displaying stability information.

8. A method as recited in claim 7, wherein said displaying of said information utilizes acoustic indicators.

9. A method as recited in claim 8, wherein said acoustic indicators utilizes a first and second noise reduction tool.

10. A method as recited in claim 9, further comprising the steps of:

(a) increasing contrast between structural vibrations and ambient noise as said first tool;

(b) highlighting changes in said structural vibrations as said structure is damaged as said second tool;

(c) creating a spectral fingerprint of said structure that changes over time;

(d) utilizing characteristics of said structure when it is healthy, subtracting said spectral fingerprint from said damaged structure spectral content;

(e) obtaining shifts in frequency power representing damage;

(f) minimizing transient frequencies; and

(g) displaying a final signal as an acoustic siren.

11. A method as recited in claim 10, wherein said Wavelet Transform Analysis further comprises allowing time and frequency localization so as to track changes in frequencies over time utilizing peak tracking algorithms.

12. A method as recited in claim 11, wherein said Empirical Mode Decomposition Analysis further comprises revealing underlying time-dependent frequency characteristics utilizing a sifting process and further comprising utilizing a stability indicator.

13. A method as recited in claim 12, wherein said Instantaneous Frequency Analysis further comprises extracting dominant frequency mode by linearly fitting instantaneous phase angle.

14. A method as recited in claim 13, wherein said Instantaneous Frequency Analysis further comprises extracting dominant frequency mode by low-pass filtering of a instantaneous frequency curve.

15. A structural stability monitoring system constructed so as to monitor the stability of a structure in real-time, said system comprising a stability monitoring device and a mounting plate, said plate constructed so as to affix said stability monitoring device of said system to a structure.

16. A system as recited in claim 15, wherein said mounting plate comprises pre-formed apertures, said plate constructed so as to limit sensor damage during installation, allow for rapid mounting of said plate and allow for rapid removal of said device.

17. A system as recited in claim 16, wherein said plate has a thickness that is constructed so as to resonate above 100 Hz.

18. A system as recited in claim 17, wherein said mounting plate comprises a heat resistant ceramic layer.

19. A system as recited in claim 17, wherein said plate comprises a flame retardant plastic constructed so as to withstand temperatures up to 400°

F.

20. A system as recited in claim 17, and further comprising thermal insulation constructed so as to insulate said plate from said structure.