Modular, wireless damage monitoring system for structures

• US 6,292,108 B1
• Filed: 09/04/1998
• Issued: 09/18/2001
• Est. Priority Date: 09/04/1997
• Status: Expired due to Term

• Current Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford Management Co.)
• Original Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford Management Co.)
• Inventors: Straser, Erik G., Kiremidjian, Anne S., Meng, Teresa H.
• Primary Examiner(s): Horabik, Michael
• Assistant Examiner(s): WONG, ALBERT KANG
• Application Number:
  US09/148,245
• Time in Patent Office: 1,110 Days
• Field of Search: 340/870.01, 340/870.21, 340/870.06, 340/429, 340/683, 340/690, 340/689, 340/601, 340/539, 340/870.11, 340/870.16, 736/49, 737/86, 737/69
• US Class Current: 340/870.11
• CPC Class Codes: G01B 21/32 for measuring the deformation in a solid

Abstract

A structural monitoring system comprises a plurality of modular, battery powered data acquisition devices which transmit structural information to a central data collection and analysis device over a wireless data link. The data acquisition devices each comprise mechanical vibration sensors, data acquisition circuitry, a digital wireless transmitter, and a battery for providing electrical power to the device. The central data collection device comprises a digital wireless receiver that receives data sent from the data acquisition devices, and a microprocessor for processing the data. A more powerful computer may be interfaced with the central device to provide more sophisticated analysis after a natural hazard or other extreme event. A methodology for operating the monitoring system is also disclosed.

Claims

1. A system for monitoring structural properties of a large civil structure during structural overloading caused by a natural hazard or other extreme event, the system comprising:

a) a plurality of self-powered sensor units, wherein each sensor unit comprises;

I) a mechanical vibration sensor mechanically coupled to the civil structure and producing an analog electrical signal representative of mechanical vibrations in a localized area of the civil structure;

ii) a data acquisition circuit electrically coupled to the mechanical vibration sensor and producing from the analog electrical signal a digital signal data stream representative of the mechanical vibrations;

iii) a digital wireless transmitter coupled to the data acquisition circuit and producing from the digital data stream a wireless signal containing digital information in the digital data stream;

iv) an electrical battery supplying power to the data acquisition circuit and to the digital wireless transmitter; and

b) a site master unit comprising;

I) a digital wireless receiver coupled to the wireless signal of each sensor unit and reproducing the digital information of each sensor unit;

ii) a microprocessor couple to the receiver and programmed to collect and to analyze the digital information from the plurality of sensor units to determine the condition of the structure as a result of a natural hazard or other extreme event.

2. The system of claim 1 wherein the mechanical vibration sensor is an accelerometer.

3. The system of claim 1 wherein the wireless signal is a spread spectrum signal.

4. The system of claim 1 wherein each sensor unit further comprises a triggering circuit coupled to the vibration sensor and to the data acquisition circuit, wherein the triggering circuit activates data acquisition when the analog electrical signal exceeds a predetermined threshold.

5. The system of claim 1 wherein each sensor further comprises a digital memory for temporarily storing the digital data stream prior to transmission.

7. The method of claim 1 wherein the sensing is performed using an accelerometer.

8. The method of claim 1 wherein the wireless signals are spread spectrum signals.

9. The method of claim 1 further comprising triggering the sensing, converting, and transmitting when a sensed vibration exceeds a predetermined threshold.

10. The method of claim 1 further comprising temporarily storing the digital signals at the plurality of locations prior to transmission.

6. A method for monitoring structural properties of a large civil structure, the method comprising:

a) sensing mechanical vibrations at a plurality of locations in the structure;

b) converting at the plurality of locations the sensed vibrations into digital signals representative of the mechanical vibrations;

c) transmitting wireless signals from the plurality of locations to a central location, wherein the wireless signals contain contain digital information in the digital signals;

d) receiving the wireless signals at the central location; and

e) storing and processing the wireless signals at the central location to provide information useful in determining the structural condition of the civil structure.