Structural monitoring sensor system

• US 6,487,914 B1
• Filed: 01/29/2001
• Issued: 12/03/2002
• Est. Priority Date: 09/14/1995
• Status: Expired due to Term

• Current Assignee: EFS International SA
• Original Assignee: Structural Integrity Monitoring Systems, Inc. (Matech Corporation)
• Inventors: Hodge, Malcolm H.
• Primary Examiner(s): NOORI, MAX H
• Application Number:
  US09/772,182
• Time in Patent Office: 673 Days
• Field of Search: 737/68, 737/74, 737/75, 737/81, 737/94, 737/95, 738/00
• US Class Current: 73/800
• CPC Class Codes: G01B 11/16 for measuring the deformation in a solid, e.g. optical strain gauge
• CPC Class Codes: G01D 5/268 using optical fibres G01D5/28 - G01D5/38 take precedence
• CPC Class Codes: G01M 11/083 by using an optical fiber in contact with the device under test [DUT]
• CPC Class Codes: G01M 5/0008 of bridges
• CPC Class Codes: G01M 5/0041 by determining deflection or stress
• CPC Class Codes: G01M 5/0091 by using electromagnetic excitation or detection

Abstract

The present invention is directed to a system for continuous physical integrity monitoring of large civil structures such as bridges and high-rise buildings . . . wherein the relevant sensor data stream is generated continuously and transmitted to the data gathering location without the need for an incoming triggering signal of any kind; i.e., it is a one way transmission system. Specifically, it is a concept for an interlinked multi-parameter Early Warning Sensor system with a full time data management capability for structures. The invention is also directed to both the system construction, with its communication capability, and also designs of specific sensors applicable to the system as a whole. As a practical example of application of the present invention to a structure, the description in this application is directed primarily towards system applications for bridge integrity early warning systems.

Claims

1. Apparatus for monitoring a structure comprising:

(a) a source of power;

(b) a transceiver assembly connect to said source of power said transceiver being adapted to transmit and receive electromagnetic radiation;

(c) at least one sensor for being operatively connected to said structure for sensing a change in a selected condition of said structure, said sensor having a first element for being connected to a first part of said structure and a second element which is connected to a second part of said structure and which moves relative to said first element as a result of the change in said selected condition, said sensor being operatively connected to said transceiver for receiving said electromagnetic radiation and for returning said electromagnetic radiation to said transceiver, said returned radiation being indicative of said change in said selected condition of said structure; and

(d) a transmitter operatively connected to said transceiver for transmitting an electromagnetic signal to a remote location which is in response to said electromagnetic radiation returned to said transceiver from said sensor.

2. Apparatus for monitoring a structure comprising:

(a) a source of power;

(b) at least one sensor operatively connected to said structure for sensing a change in a selected condition of said structure, said sensor having the capacity to undergo a physical change in response to a change in said selected condition, so that said sensor has at least two states, said sensor being capable of receiving an electromagnetic signal and for transmitting said electromagnetic signal, the nature of said transmitted electromagnetic signal being dependent on the particular state of said sensor;

(c) a transceiver operatively connected to said source of power and to said sensor for transmitting pulses of electromagnetic signals to said sensor and for receiving electromagnetic signals from said sensor, said sensors are connected to said transceiver by a first transmitting line and by a second transmitting line, said second transmitting line being substantially longer than said first transmitting line for enabling implementation of a time division multiplexed quadrature incremental sensor interrogation program to be used;

(d) a transmitter operatively connected to said source of power and said transceiver for transmitting electromagnetic signals to a location remote from said structure in response to electromagnetic signals received by said transceiver from said sensor.

3. Apparatus for monitoring a structure as recited in claim 2 wherein said apparatus comprises a plurality of sensors.

4. Apparatus for monitoring a structure as recited in claim 3, wherein the electromagnetic signals received by said transceiver are automatically correlated with one another for verification purposes.

5. Apparatus for monitoring a structure as recited in claim 2, wherein said transceiver transmits said pulses continuously for constant monitoring of said structure.

6. Apparatus for monitoring a structure comprising:

(a) a source of power;

(b) a transceiver connected to said source of power, said transceiver being adapted to transmit and receive pulses of electromagnetic radiation;

(c) at least one digital sensor operatively connected to said structure for sensing a change in a selected condition of said structure, said sensor having a first element operatively connected to a first part of said structure and a second element operatively connected to a second part of said structure and which moves relative to a said first element as a result of a change in said selected condition, said sensor being operatively connected to said transceiver for receiving said pulses of electromagnetic radiation and for selectively returning said pulses of electromagnetic radiation to said transceiver in digital on/off mode in accordance with the relative positions of the first and second elements of said sensor, the return and non return of said pulses of electromagnetic radiation being indicative of said change in a selected condition of said structure; and

(d) a transmitter operative connected to said transceiver for transmitting an electromagnetic signal to a remote location which is in response to the return and non return of said pulses of electromagnetic radiation to said transceiver from said sensor.

10. Apparatus for monitoring a structure as recited in claim 6, wherein said apparatus comprises a plurality of optical sensors and said transceiver is connected to each of said optical sensors by at least one optical fiber, said pulses of electromagnetic radiation being light which is transmitted along each of said optical fibers.

7. Apparatus for monitoring a structure comprising:

(a) a source of power;

(b) at least one digital sensor operatively connected to said structure for sensing a change in a selected condition of said structure, said sensor having the capacity to undergo a physical change in response to a change in said selected condition, so that said sensor has an off state and an on state, said sensor being capable of receiving pulses of electromagnetic radiation and for selectively returning said pulses of electromagnetic radiation in digital on/off made in accordance with the state of said sensor, said pulses of electromagnetic radiation being returned when said sensor is on and not returned when said sensor is off, the the return and non return of said pulses of electromagnetic radiation being indicative of said change in a selected condition of said structure;

(c) a transceiver operatively connected to said source of power and to said sensor for transmitting pulses of electromagnetic radiation to said sensor and for receiving pulses of electromagnetic radiation from said sensor;

(d) a transmitter operatively connected to said source of power and said transceiver for transmitting electromagnetic signals to a location remote from said structure in response to the return and non return of said pulses of electromagnetic radiation to said transceiver from said sensor.

8. Apparatus for monitoring a structure as recited in claim 7, wherein said apparatus comprises a plurality of sensors.

9. Apparatus for monitoring a structure as recited in claim 7, wherein the pulses of electromagnetic radiation returned to said transceiver are automatically correlated with one another for verification purposes.

12. Apparatus for monitoring a structure as recited in claim 7, wherein said transceiver transmits said pulses continuously for constant monitoring of said structure.

11. Apparatus for monitoring a structure comprising:

(a) a source of power;

(b) at least one sensor operatively connected to said structure for sensing a change in a selected condition of said structure, said sensor having the capacity to undergo a physical change in response to a change in said selected condition, so that said sensor has at least two states, said sensor being capable of receiving pulses of electromagnetic signals and for transmitting said pulses of electromagnetic signals, the nature of the transmission of said pulses of electromagnetic signals being dependent on the particular state of said sensor;

(c) a transceiver operatively connected to said source of power for transmitting first and second pulses of electromagnetic signals and for receiving said first and second pulses of electromagnetic signals;

(d) a first transmitting line connected to said transceiver and to sensor for enabling said first pulses of electromagnetic signals to be received by said sensor from said transceiver and for enabling said first pulses of electromagnetic signals to be received by said transceiver from said sensor;

(e) a second transmitting line connected to said transceiver and to said sensor for enabling said second pulses of electromagnetic signals to be received by said sensor from said transceiver and for enabling said second pulses of electromagnetic signals to be received by said transceiver from said sensor, said second transmitting line being substantially longer than said first transmitting line for enabling implementation of a time division multiplexed quadrature incremental sensor interrogation program to be used; and

(f) a transmitter operatively connected to said source of power and to said transceiver for transmitting electromagnetic signals to a location remote from said structure in response to said first and second pulses of electromagnetic signals received by transceiver from said sensor.

13. Apparatus for monitoring a structure comprising:

(a) a source of power;

(b) a plurality of optical sensors, said sensor having the capacity to undergo a physical change in response to a change in said selected condition, so that said sensor has at least two states, said sensor being capable of receiving pulses of light signal and for transmitting said pulses of light, the nature of said transmitted pulses of light being dependent on the particular state of said sensor;

(c) a transceiver operatively connected to said source of power and to each of said optical sensors by at least one optical fiber said sensor for transmitting pulses of to said sensor and for receiving said pulses of light from said sensor;

(d) a transmitter operatively connected to said source of power and said transceiver for transmitting electromagnetic signals to a location remote from said structure in response to said pulses of light received by said transceiver from said sensor; and

(e) a drone cable for being connected to said structure and operatively connected to said optical sensors so that a change in a selected condition of said structure are transmitted to each of said sensors through said drone cable for enabling each of said sensors to sense a change in said selected condition, said optical fibers being arranged as an optical fiber cable for deployment along said structure and at least one optical fiber from said optical fiber cable being directed from said optical fiber cable to each of said optical sensors, thereby enabling said drone cable to be made of a material which has desirable characteristics for physically transmitting changes in the selected condition of said structure and for deployment in environmentally hazardous areas and enabling said optical fiber cable to passively deploy in environmentally safe areas of the structure.

14. Apparatus for monitoring a structure as recited in claim 13, wherein said drone cable is made of an aramid fiber.

15. Apparatus for monitoring a structure as recited in claim 13, wherein said photo sensor has a first element and a second element which is movable relative to said first element, said drone cable having a first length which is connected to a first part of said structure and to said first element and a second length which is connected to a second part of said structure and to said second element.