| US4734577A | 1988-03-29 | |||
| US5701370A | 1997-12-23 | |||
| JP2011169592A | 2011-09-01 |
| CLAIMS 1 . A system for the measuring of integrated deformations along one direction of a structure via an optical fiber sensor, comprising a device for the measuring of the deformations of said structure , wherein said measuring device comprises the following components : A first stage , comprising a series of digital potentiometers , said digital potentiometers being settable to an optimal gain value via a Microprocessor, the arrangement being such that an output current of a photodiode associated with a polymer optical fiber is converted into an optimal voltage value at an input of an Analog/Digital converter ; A second stage , comprising said Analog/Digital converter capable of carrying out a high-resolution measuring of signals coming from said photodiode once said signals are converted into voltage ; and - A third stage , comprising said Microprocessor capable of managing the entire measuring; characterized in that said microprocessor performs the following operations : a ) automatically setting the entire system to obtain the maximum possible dynamics ; b ) communicating with said Analog/Digital converter ; and c ) communicating with a "Host Unit" for data acquisition and processing . 2 . A system for the measuring of integrated deformations along one direction of a structure via an optical fiber sensor according to the preceding claim, wherein said optical fiber sensor is a sensor made of polymeric optical fiber . 3. A system for the measuring of integrated deformations along one direction of a structure via an optical fiber sensor according to the preceding claim, wherein said optical fiber sensor is arranged onto the surface of said structure according to a determined geometric pattern consisting of a sinusoidal pattern and along a direction of said structure . 4 . A system for the measuring of integrated deformations along one direction of a structure via an optical fiber sensor according to any of the preceding claims , wherein the geometry of said sensor is such that a variation of a tensile stress applied to the fiber of said sensor causes an increase in the signal detected by said photodiode associated with said fiber . 5 . A system for the measuring of integrated deformations along one direction of a structure via an optical fiber sensor according to any of the preceding claims , wherein the geometry of said sensor is such that a variation in a compressive stress applied to said optical fiber of said sensor causes an attenuation in the signal detected by said photodiode associated with said fiber . |
A DIRECTION OF A STRUCTURE BY MEANS OF AN OPTICAL FIBER
SENSOR, AND A SYSTEM FOR THE IMPLEMENTATION OF SAID METHOD" >»X<« DESCRIPTION
The present invention relates to a method for the measuring of integrated deformations of a structure using a optical fiber sensor and, more precisely, to a method for the measuring of integrated deformations of a structure , which provides the use of a system comprising an elastic optical fiber sensor arranged on the surface of the structure according to a determined geometric pattern, the sensor being able to detect the deformation of the structure along a direction thereof and following the deformation of the sensor .
State of the art
As is known, today there are di f ferent types of methods and related systems for the measuring of deformations by using optical fibres . These deformation measuring systems find application in the monitoring and the measuring of deformations in civil building such as dams , bridges , tunnels , etc . but also di f ferent applications such as the measuring of deformations for particular structures .
According to a first type of such systems , the use of the so-called "punctual sensors" in the "Bragg grating" technology is foreseen . Alternatively, other types of measuring systems provide the use of "distributed sensors" , which are able to measure deformation profiles along the entire length of the fiber (via Brillouin scattering) . Both of these types of systems involve technologies that show signi ficant costs , and which limit the use thereof to cases wherein the monitoring of deformations must be performed in particularly noi sy environments from an electromagnetic point of view (Bragg grating sensors ) , or where it is necessary to monitor deformation profiles on very long stretches ( such as , for example , dams , bridges , tunnels , etc . ) , and where the value of the deformation at all points coinciding with the spatial resolution of the system is needed to be known .
The aforementioned technologies have the enormous disadvantage given that they find it very di f ficult to be applied in all those circumstances in which the cost of the measuring system has a considerable impact with respect to the application thereof . For example , in the monitoring of rockfall protection networks , in the monitoring of geocomposites for the consolidation of landslide slopes , and wherever it is suf ficient to measure the integral deformation of the support on which the fiber is applied .
Aim of the present invention is to solve the above mentioned disadvantages of the aforementioned state-of-the- art technologies , by providing a method for the measuring of integrated deformations of a structure wherein the use of a system which includes an elastic optical fiber sensor arranged onto the surface of the structure and according to a determined geometric pattern is provided, and which is capable of detecting the deformation along a direction of the structure and following deformation of the sensor .
BRIEF DESCRIPTION OF THE INVENTION Therefore , the present invention provides a method for the measuring of integrated deformations which involves the use of a system which includes a polymer optical fiber sensor, the sensor being capable of being mounted on the surface of a structure to be measured and according to a speci fic geometric arrangement , and in such a way as to detect the deformation along a direction following the deformation of the sensor .
Therefore , the present invention provides a method and a system for the measuring of deformations of a structure substantially according to the appended claims .
According to a first inventive aspect of the present invention, the system foresees the use of a polymeric optical fiber which, when applied onto the surface of the structure to be measured and according to a speci fic geometric arrangement , it allows the measuring of the integral deformation applied along a speci fic measuring axis of the structure .
According to a second inventive aspect , the geometry of the sensor is substantially a sinusoidal geometry .
According to a third inventive aspect of the present invention, the variation of the tensile stress appl ied onto the fiber of the sinusoidal-shaped sensor generates an increase in the signal detected by a photodiode associated with the fiber .
According to a fourth inventive aspect , the variation of the compressive stress applied on the fiber of the sinusoidal-shaped sensor generates an attenuation of the signal detected by a photodiode associated with the fiber . DETAILED DESCRIPTION OF THE INVENTION
A detailed description of a preferred embodiment of the method and the system for the measuring of integrated deformations of a structure using the optical fiber sensor of the present invention will now be provided, given by way of a not limiting example , and with reference to the attached drawings , wherein :
Figure 1 is a schematical view illustrating the geometric arrangement of the sensor of the measuring system of the present invention;
Figure 2 is a schematical view illustrating a first operating condition of the sensor of the measuring system of the present invention; and
Figure 3 is a schematical view illustrating a second operating condition of the sensor of the measuring system of the present invention .
With reference now to figure 1 , according to the present invention a measuring system for a structure is provided, the system comprising a device for the measuring of the deformations of the structure, which substantially comprises the following components :
- A first stage which includes a series of digital potentiometers , the potentiometers being set by a microprocessor to an optimal gain value , the arrangement is such that the output current of a photodiode associated with a polymer optical fiber is converted into a value o f optimal voltage at an input of an Analog/Digital converter, and with the aim of guaranteeing maximum measuring dynamics depending on the system configuration; - A second stage which comprises an Analog/Digital converter which measures , at high resolution, the signals coming from the photodiode , appropriately converted into voltage ; and
- A third stage which includes a microprocessor that manages the entire measuring .
The aforementioned microprocessor has the following functions : a ) automatically setting of the entire system, to guarantee the maximum possible dynamics ; b ) communicating with the Analog/Digital converter ; and c ) communicating with a "Host Unit" for data acquisition and processing .
As can be seen in the figure and according to the present invention, the optical fiber sensor is a sensor made of a polymeric optical fibre , which is arranged onto the surface of a structure ( the latter not being illustrated in the figure ) and according to a speci fic geometric arrangement , the arrangement essentially consisting of a sinusoidal pattern . The optical fiber sensor is mounted onto the surface of the structure to be measured along a determined direction .
It is necessary to highlight here that the use of a polymer optical fiber allows the measuring of the integral deformation applied along a given measuring axis .
Furthermore , being the geometry of the sensor substantially a sinusoidal shaped geometry, following to a variation of a tensile stress applied to the sensor fiber, it causes an increase in the signal detected by the photodiode associated with the optical fiber sensor .
On the other hand, following to a variation of a compressive stress applied to the optical fiber sensor, it generates an attenuation of the signal detected by the photodiode associated with the optical fiber sensor .
As can be understood in figure 2 , by applying a tensile stress on the fiber it causes a decrease in attenuation along the fiber, and consequently an increase of the signal detected by the photodiode .
As illustrated in figure 3 , by applying a compressive stress on the fiber it causes an attenuation of the signal detected by the photodiode .
The variation of the signal to the photodiode is processed by the microprocessor which trans forms the former into a value/parameter related to a determined deformation value relevant to the structure associated to the fiber sensor .