Method and system for remote monitoring deformations of a structure

• US 8,410,924 B2
• Filed: 05/02/2008
• Issued: 04/02/2013
• Est. Priority Date: 05/04/2007
• Status: Expired due to Fees

• Current Assignee: Alma Mater Studiorum Universita' Di Bologna (Repubblica Italiana)
• Original Assignee: Alma Mater Studiorum Universita' Di Bologna (Repubblica Italiana)
• Inventors: Benedetti, Andrea, Rizzoli, Vittorio, Costanzo, Alessandra
• Primary Examiner(s): Tweel, Jr., John A
• Application Number:
  US12/598,889
• Publication Number:
  US 20100201378A1
• Time in Patent Office: 1,796 Days
• Field of Search: 340/539.1, 737/63, 737/67, 737/73, 737/81, 296/211
• US Class Current: 340/539.1
• CPC Class Codes: G01M 5/0041 by determining deflection or stress
• CPC Class Codes: G01M 5/0091 by using electromagnetic excitation or detection

Abstract

A low-cost and non-invasive method for remote monitoring deformations of a structure (2), which method envisages to couple at least two RFID tags (3) to the structure (2) in its respective points (10a, 10b, 10a-10c), to interrogate at radio frequency the RFID tags (3) so that a resultant electromagnetic field is produced at a certain distance (DINF) from the structure (2), the resultant electromagnetic field ensuing from a combination of the electromagnetic fields produced individually by each RFID tags (3) in response to the interrogation, to measure the resultant electromagnetic field at such a distance (DINF) from the structure (2) for obtaining measurements of the resultant electromagnetic field, and to determine the deformations of the structure (2) as a function of the measurements of the resultant electromagnetic field.

Claims

1. Method for remote monitoring deformations of a structure (2), which method comprises:

coupling at least two RFID tags (3) to the said structure (2) in respective points (9a, 9b;

9a-9c) of the structure (2) itself;

interrogating at radio frequency the RFID tags (3) so that a resultant electromagnetic field is produced at a certain distance (DINF) from said structure (2), said resultant electromagnetic field ensuing from a combination of the electromagnetic fields singularly produced by the RFID tags (3) in response to the interrogation;

measuring the electromagnetic field at said certain distance (DINF) to obtain measurements of said resultant electromagnetic field; and

determining said deformations of the structure (2) as a function of the measurements of the resultant electromagnetic field.

2. Method according to claim 1, wherein coupling at least two RFID tags (3) to said structure (2) comprises coupling at least three RFID tags (3) to the structure (2) in respective points (10a-10c) of the structure itself;

interrogating at radio frequency said RFID tags (3) comprising interrogating said RFID tags (3) in pairs;

measuring the electromagnetic field at said certain distance (DINF) comprising measuring the electromagnetic field to obtain measurements of said resultant electromagnetic field produced by each interrogation of RFID tags (3) in pairs.

3. Method according to claim 2, wherein interrogating said RFID tags (3) in pairs comprises interrogating at least one of the combinations without repetition of two RFID tags (3).

4. Method according to claim 1, wherein said measurements of said resultant electromagnetic field comprise measurements of amplitude of the resultant electromagnetic field;

determining said deformations of the structure (2) comprising;

determining null directions of the resultant electromagnetic field from the amplitude measurements;

determining said deformations as a function of the null directions.

5. Method according to claim 1, wherein said measurements of said resultant electromagnetic field comprise measurements of phase of the resultant electromagnetic field;

said deformations of the structure (2) being deteirmined as a function of the phase measurements.

6. Method according to claim 1, wherein said points (10a, 10b;

10a-10c) of said structure (2) are positioned, at the time of coupling said RFID tags (3) to said structure (2), according to a reference arrangement;

measuring the electromagnetic field at said certain distance (DINF) comprising;

obtaining reference measurements of the resultant electromagnetic field corresponding to said reference arrangement; and

obtaining following monitoring measurements of the resultant electromagnetic field;

determining said deformations of the structure (2) as a function of said measurements of the resultant electromagnetic field comprising;

comparing the monitoring measurements with the reference measurements to determine variations of said resultant electromagnetic field; and

determining the deformations as a function of the variations of the resultant electromagnetic field.

7. Method according claim 1, wherein said deformations of the structure (2) comprise distance variations between said points (10a, 10b;

10a-10c) of the structure (2).

8. Method according to claim 7, wherein said distances between said points (10a, 10b;

10a-10c) of the structure (2) consist of the distances of the points (10a, 10b;

10a-10c) from the first (10a) of them.

9. Method according to claim 7, wherein said points (10a, 10b;

10a-10c) of the said structure (2) are positioned, at the time of coupling said RFID tags (3) to said structure (2), at reference distances (D;

Dab, Dac, Dbc) from each other;

said distance variations between these points (10a, 10b, 10a-10c) being expressed referring to said reference distances (D;

Dab, Dac, Dbc).

10. Method according to claim 1, comprising:

associating a further RFID tag (3) at a determined reference point (13);

said deformations of the structure (2) comprising displacements of said points (10a, 10b;

10a-10c) of the structure (2) with respect to said reference point (13).

11. Method according to claim 10, wherein said points (10a, 10b;

10a-10c) of the structure (2) are positioned, at the moment of coupling said RFID tags (3) to said structure (2), at respective reference distances (Da, Db;

Da-Dc) from said reference point (13);

said displacements being defined by variations of distances between said points (10a, 10b;

10a-10c) of the structure (2) and said reference point (13) with respect to said reference distances (Da, Db;

Da-Dc).

12. Method according to claim 1, wherein said distance (DINF) is such that said RFID tags (3) are comparable, at said certain distance (DINF) from the structure (2), to punctiform sources of electromagnetic field.

13. Method according to claim 1, wherein interrogating at radiofrequency said RFID tags (3) comprises:

interrogating the RFID tags (3) in such a manner that they simultaneously produce respective electromagnetic fields that interfere with each other in a coherent manner thus producing said resultant electromagnetic field.

14. Method according to claim 13, wherein said electromagnetic fields simultaneously produced from the RFID tags (3) exhibit the same frequency (F) and phase.

15. Method according to claim 1, wherein each of the RFID tags (3) is of the kind operating in the microwave band.

16. Method according to claim 1, wherein each of the RFID tags (3) is of the kind operating in the millimetre wave band.

17. System for remote monitoring deformations of a structure (2), the system (1) comprising:

at least two RFID tags (3) designed for being coupled to said structure (2) in respective points (9a, 9b;

9a-9c) of the structure (2) itself;

interrogator means (6) for interrogating at radio frequency the RFID tags (3);

electromagnetic field measurement means (7) for obtaining measurements of a resultant electromagnetic field produced by said RFID tags (3) in response to the interrogation;

processing means (8) designed for controlling said interrogator means (6) and said measurement means (7) for acquiring and processing said measurements;

said processing means (8) being configured to implement the method for remote monitoring deformations of a structure (2) according to claim 1.

18. Method for remote monitoring displacements of points of a structure (2), which method comprises:

coupling at least one RFID tag (3) to said structure (2) in a respective point to be monitored (10b;

10b, 10c;

10a, 10b, 10c) of the structure (2) itself;

associating a further RFID tag (3) to a determined reference point (10a;

13);

interrogating at radio frequency the RFID tags (3) so that a resultant electromagnetic field is produced at a certain distance (DINF) from said structure (2), said resultant electromagnetic field ensuing from a combination of the electromagnetic fields individually produced by the RFID tags (3) in response to the interrogation;

measuring the electromagnetic field at said certain distance (DINF) to obtain measurements of said resultant electromagnetic field; and

determining displacements of said point to be monitored (10b;

10b,10c;

10a, 10b, 10c) as a function of said measurements of the resultant electromagnetic field.

19. Method according to claim 18, wherein said reference point (10a;

13) and said point to be monitored (10b;

10b, 10c;

10a, 10b, 10c) are positioned, at the moment of coupling said RFID tags (3) to said structure (2), according to a reference arrangement;

measuring the electromagnetic field at said certain distance (DINF) comprising;

obtaining reference measurements of the resultant electromagnetic field corresponding to said reference arrangement; and

obtaining following monitoring measurements of the resultant electromagnetic field;

deteimining displacements of said point to be monitored (10b;

10b, 10c;

10a, 10b, 10c) as a function of said measurements of the resultant electromagnetic field comprising;

comparing the monitoring measurements with the reference measurements to determine variations of said resultant electromagnetic field; and

determining the displacements as a function of the variations of the resultant electromagnetic field.

20. Method according to claim 18, wherein said reference point (10a) is a point of said structure (2);

the RFID tag (3) associated to the reference point (10a) being coupled to the structure (2) in the reference point (10a) itself.

21. Method according to claim 18, wherein said point to be monitored (10b;

10b, 10c;

10a, 10b, 10c) is positioned, at the moment of coupling said RFID tag (3) to said structure (2), at a respective reference distance (D;

Dab, Dac;

Da, Dc, Dc) from said reference point (10a;

13) with respect to said reference distance (D;

Dab, Dac;

Da, Dc, Dc);

said displacements being defined by variations of a distance between said point to be monitored (10b;

10b, 10c;

10a, 10b, 10c) and said reference point (10a;

13) with respect to said reference distance (D;

Dab, Dac;

Da, Dc, Dc).

22. System for remote monitoring displacements of points of a structure (2), the system (1) comprising:

at least two RFID tags (3), al least a first of which is designed to be coupled to said structure (2) in a respective point to be monitored (10b;

10b, 10c;

10a, 10b, 10c) of the structure (2) itself and a second of which is designed to be associated to a certain reference point (10a;

13);

interrogator means (6) for interrogating at radio frequency the RFID tags (3);

electromagnetic field measurement means (7) for obtaining measurements of a resultant electromagnetic field produced by said RFID tags (3) in response to the interrogation;

processing means (8) designed for controlling said interrogator means (6) and said measurement means (7) for acquiring and processing said measurements;

said processing means (8) being configured to implement the method for remote monitoring displacements of points of a structure (2) according to claim 18.