DISPLACEMENT AND DEFORMATION MONITORING METHOD AND SYSTEM WITHOUT USING ANY STRAIN SENSOR, AND COMPONENTS THEREOF

• US 20190162606A1
• Filed: 01/30/2019
• Published: 05/30/2019
• Est. Priority Date: 04/21/2017
• Status: Active Grant

• Current Assignee: Colorado State University Research Foundation
• Original Assignee: Colorado State University Research Foundation
• Inventors: PUTTLITZ, Christian M., DEMIR, Hilmi Volkan, LABUS, Kevin M., MCGILVRAY, Kirk C., UNAL, Emre
• Granted Patent: US 10,641,664 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 2562/0261 Strain gauges
• CPC Class Codes: A61B 5/05 Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves impedance plethysmography A61B5/0295; measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24
• CPC Class Codes: A61B 5/0507 using microwaves or terahertz waves
• CPC Class Codes: A61B 5/4504 Bones A61B5/4547 takes precedence
• CPC Class Codes: A61B 5/4851 Prosthesis assessment or monitoring
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: G01B 15/06 for measuring the deformation in a solid
• CPC Class Codes: G01B 7/22 using change in capacitance
• CPC Class Codes: G01B 7/24 using change in magnetic properties
• CPC Class Codes: G01L 1/00 Measuring force or stress, in general measuring force due to impact G01L5/00
• CPC Class Codes: G01L 1/127 by using inductive means G01L1/122, G01L1/125 take precedence
• CPC Class Codes: G01L 1/14 by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators
• CPC Class Codes: G01M 1/00 Testing static or dynamic balance of machines or structures
• CPC Class Codes: G01M 5/0041 by determining deflection or stress
• CPC Class Codes: G01M 5/0091 by using electromagnetic excitation or detection
• CPC Class Codes: G01N 3/00 Investigating strength properties of solid materials by application of mechanical stress
• CPC Class Codes: G01N 3/066 with electrical indicating or recording means
• CPC Class Codes: G01N 3/20 by applying steady bending forces G01N3/26, G01N3/28 take precedence

Abstract

A monitoring method and system include an antenna disposed spaced from a structural member (SM), which itself can be the target object or attachable to a target object, without using any in-dwelling strain sensor. The antenna is arranged to not touch the SM in at least the no load condition. As the target object undergoes displacement and/or deformation, the SM undergoes displacement and/or deformation. The SM is juxtaposed, partially contained with, or fully contained within a magnetic or electromagnetic field and electromagnetically coupled to the emitting antenna. Characteristics of the electromagnetic field coupling between the antenna and the SM shift over time due to the displacement and/or deformation applied to the SM. The shift in the characteristics of the electromagnetic field coupling between the antenna and the SM over time can be used to determine the temporal change in deformation and/or displacement of the SM over time to enable diagnosis of the target structural object being monitored.

Claims

1. A method of monitoring changes in a structural member (SM) as the SM undergoes at least one of displacement or deformation, the method comprising:

a disposing step of disposing an antenna spaced from the SM so that the antenna does not contact the SM at least at no load condition;

an inducing step of inducing a magnetic or electromagnetic field in the vicinity of the SM to create a coupling of the magnetic or electromagnetic field between the antenna and the SM, where characteristics of the magnetic or electromagnetic field coupling between the antenna and the SM are associated with one of the distance between the SM and the emitting antenna or the deformation state of the SM;

an outputting step of outputting electrical signals representing the characteristics of the magnetic or electromagnetic field coupling between the antenna and the SM, without using any strain sensing device directly attached to the SM;

a first determining step of determining the characteristics of the magnetic or electromagnetic field coupling between the antenna and the SM based on the electrical signals; and

a storing step of storing the determined characteristics of the magnetic or electromagnetic field coupling between the antenna and the SM in a storage device.

2. The method according to claim 1, further comprising:

a repeating step of repeating the inducing step, the outputting step, the first determining step, and the storing step at a predetermined interval for one of an evaluation period or until a predetermined number of the characteristics of the magnetic or electromagnetic field coupling between the antenna and the SM has been determined.

3. The method according to claim 2, further comprising:

a second determining step of determining a shift in characteristics of the magnetic or electromagnetic field coupling between the antenna and the SM over the evaluation period or a time lapsed to determine the predetermined number of the characteristics of the magnetic or electromagnetic field coupling between the antenna and the SM.

4. The method according to claim 3, further comprising:

a third determining step of determining a temporal change in relative displacement or deformation of the SM over the evaluation period or the time lapsed based on the shift determined in the second determining step.

5. The method according to claim 1, wherein the SM is mountable to a target object to be monitored, the SM undergoing the at least one of displacement or deformation as the target structural object undergoes at least one of displacement or deformation.

6. The method according to claim 1, further comprising:

a loading step of applying a known or measurable force or moment to the SM; and

an analyzing step of analyzing the determined characteristics in relation to the known or measurable force of moment applied to the SM in the loading step.

7. The method according to claim 5, further comprising:

a loading step of applying a known or measurable force or moment to the SM; and

an analyzing step of analyzing the determined characteristics in relation to the known or measurable force of moment applied to the SM in the loading step.

8. The method according to claim 1, wherein:

the inducing step comprises using the antenna that has at least one wire configured to induce the magnetic or electromagnetic field and output the electrical signals, which is readable by a network analyzer, and

the at least one wire is connectable to an input port of the network analyzer.

9. The method according to claim 8, wherein the at least one wire comprises a coaxial cable.

10. The method according to claim 1, wherein:

the inducing step comprises using the antenna that has a first wire configured to induce the magnetic or electromagnetic field; and

the outputting step comprises using the antenna that further has a second wire configured to output the electrical signals, which is readable by a network analyzer, and

the first and second wires are connectable respectively to first and second input ports of the network analyzer.

11. The method according to claim 9, wherein each of the first and second wires comprises a coaxial cable.

12. The method according to claim 4, wherein the change in relative displacement or deformation of the SM over the evaluation period or the lapsed time is represented as a slope of resonant frequency/load.

13. The method according to claim 12, wherein a degree of the slope represents stability, with a higher slope representing a more unstable condition and a less slope representing a more stable condition.

14. A system for monitoring changes in a structural member (SM) as the SM undergoes one of displacement or deformation, the system comprising:

an antenna configured to;

induce, using a first electrical signal, a magnetic or electromagnetic field in the vicinity of the SM to create a coupling of the magnetic or electromagnetic field between the antenna and the SM, where characteristics of the magnetic or electromagnetic field coupling between the antenna and the SM are associated with one of the distance between the SM and the emitting antenna or the deformation state of the SM; and

output a second electrical signal representing the magnetic or electromagnetic field coupling between the antenna and the SM, without using any strain sensing device directly attached to the SM;

an antenna holder configured to hold the antenna at a fixed distance from the SM so that the antenna is spaced from the SM and not contact the SM at least at no load condition;

a network analyzer configured to;

output the first electrical signal to the antenna for inducing the magnetic or electromagnetic field;

receive the second electrical signal from the antenna; and

determine the characteristics of the magnetic or electromagnetic field coupling between the antenna and the SM based on the received second electrical signal;

a controller including a memory storing instructions and a processor configured to implement instructions stored in the memory and execute;

a collecting task that stores, in the memory or another storage device, a plurality of characteristics of the magnetic or electromagnetic field coupling between the antenna and the SM determined at a predetermined interval by the network analyzer over an evaluation period;

a first determining task that determines a shift in characteristics of the magnetic or electromagnetic field coupling between the antenna and the SM over the evaluation period; and

a second determining task that determines a temporal change in relative deformation or displacement of the SM over the evaluation period.

15. The system according to claim 14, wherein:

the antenna comprises at least one wire configured to receive the first signal to induce the magnetic or electromagnetic field, and output the second signal, and

the at least one wire is connectable to at least one input port of the network analyzer.

16. The system according to claim 14, wherein:

the antenna comprises a first wire configured to receive the first signal to induce the magnetic or electromagnetic field and a second wire configured to output the second electrical signal, and

the first and second wires are connectable respectively to first and second input ports of the network analyzer.

17. The system according to claim 15, wherein the at least one wire comprises a coaxial cable.

18. The system according to claim 16, wherein each of the first and second wires comprises a coaxial cable.

19. The system according to claim 14, further comprising:

antenna interface including an antenna housing mountable to the SM and the antenna mounted to the housing, and

wherein the second determining task determines the temporal change in relative deformation or displacement of the SM over the evaluation period, which is a predetermined evaluation period, using the second electrical signal.

20. A system for monitoring change in a structural member (SM) as the SM undergoes one of deformation or displacement, the system comprising:

an antenna configured to;

induce, using a first electrical signal, a magnetic or electromagnetic field in the vicinity of the SM to create a coupling of the magnetic or electromagnetic field between the antenna and the SM, where the characteristics of the magnetic or electromagnetic field coupling between the antenna and the SM are associated with one of the distance between the SM and the emitting antenna or the deformation state of the SM; and

output a second electrical signal representing the magnetic or electromagnetic field coupling between the antenna and the SM, without using any strain sensing device directly attached to the SM;

an antenna holder configured to hold the antenna at a fixed distance from the SM so that the antenna is spaced from the SM and not contact the SM at least at no load condition;

a controller including a memory storing instructions and a processor configured to implement instructions stored in the memory; and

a hardware interface configured to output the first electrical signal to the antenna and receive the second electrical signal and convert the received electrical signal to a third signal readable by the controller,

wherein the processor is configured to execute;

a first determining task that receives the third electrical signal from the hardware interface and determines characteristics of the magnetic or electromagnetic field coupling between the antenna and the SM based on the third signal;

a repeating task that repeats the first determining task to obtain a plurality of characteristics of the magnetic or electromagnetic field coupling between the antenna and the SM determined by the first determining task at a predetermined interval over an evaluation period;

a second determining task that determines a shift in characteristics of the magnetic or electromagnetic field coupling between the antenna and the SM after each occurrence of the first determining task determining twice the characteristics of the magnetic or electromagnetic field coupling between the antenna and the SM at the predetermined interval, or collectively at the end of the evaluation period; and

a third determining task that determines a temporal change in relative deformation or displacement of the SM over the evaluation period.

21. The system according to claim 20, wherein:

the antenna comprises at least one wire configured to receive the first signal to induce the magnetic or electromagnetic field, and output the second signal, and

the at least one wire is connectable to at least one input port of the hardware interface.

22. The system according to claim 20, wherein:

the antenna comprises a first wire configured to receive the first signal to induce the magnetic or electromagnetic field and a second wire configured to output the second electrical signal, and

the first and second wires are connectable respectively to first and second input ports of the hardware interface.

23. The system according to claim 21, wherein the at least one wire comprises a coaxial cable.

24. The system according to claim 22, wherein each of the first and second wires comprises a coaxial cable.

25. The system according to claim 20, further comprising:

antenna interface including an antenna housing mountable to the SM and the antenna mounted to the housing, and

wherein the third determining task determines the temporal change in relative deformation or displacement of the SM over the evaluation period, which is a predetermined evaluation period, using the second electrical signal.

26. An apparatus for monitoring change in a structural member (SM) as the SM undergoes one of deformation or displacement, using an antenna configured to:

induce, using a first electrical signal, a magnetic or electromagnetic field in the vicinity of the SM to create a coupling of the magnetic or electromagnetic field between the antenna and the SM, where the characteristics of the magnetic or electromagnetic field coupling between the antenna and the SM are associated with one of the distance between the SM and the emitting antenna or the deformation state of the SM; and

output a second electrical signal representing the magnetic or electromagnetic field coupling between the antenna and the SM into a second electrical signal, without using any strain sensing device directly attached to the SM,

wherein the apparatus comprises;

a controller including a memory storing instructions and a processor configured to implement instructions stored in the memory; and

a hardware interface configured to output the first electrical signal to the antenna and receive the second electrical signal and convert the received electrical signal to a third signal readable by the controller,

wherein the processor is configured to execute;

a first determining task that receives the third electrical signal from the hardware interface and determines the characteristics of the magnetic or electromagnetic field coupling between the antenna and the SM based on the third electrical signal;

a repeating task that repeats the first determining task to obtain a plurality of characteristics of the magnetic or electromagnetic field coupling between the antenna and the SM determined by the first determining task at a predetermined interval over an evaluation period;

a second determining task that determines a shift in characteristics of the magnetic or electromagnetic field coupling between the antenna and the SM after each occurrence of the first determining task determining twice the characteristics of the magnetic or electromagnetic field coupling between the antenna and the SM at the predetermined interval, or collectively at the end of the evaluation period; and

a third determining task that determines a temporal change in relative deformation or displacement of the SM over the evaluation period.