WO2019212348A1 - Module de capteur pour surveillance de charge - Google Patents

Module de capteur pour surveillance de charge Download PDF

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Publication number
WO2019212348A1
WO2019212348A1 PCT/NL2019/050260 NL2019050260W WO2019212348A1 WO 2019212348 A1 WO2019212348 A1 WO 2019212348A1 NL 2019050260 W NL2019050260 W NL 2019050260W WO 2019212348 A1 WO2019212348 A1 WO 2019212348A1
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WO
WIPO (PCT)
Prior art keywords
sensor
optic
sensor module
carrier
longitudinal
Prior art date
Application number
PCT/NL2019/050260
Other languages
English (en)
Inventor
Bastiaan Meulblok
Devrez Mehmet Karabacak
Eric Meijer
Johannes Maria Singer
Original Assignee
Fugro Technology B.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fugro Technology B.V. filed Critical Fugro Technology B.V.
Publication of WO2019212348A1 publication Critical patent/WO2019212348A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
    • G01L1/242—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
    • G01L19/04—Means for compensating for effects of changes of temperature, i.e. other than electric compensation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
    • G01M5/0041—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by determining deflection or stress

Definitions

  • the present invention pertains to a sensor module for load monitoring.
  • the present invention further pertains to an optic sensor system
  • the present invention still further pertains to an application wherein the optic sensor system is used to monitor loads exerted on an artifact.
  • fiber optic sensors are known for purpose of load monitoring in artifacts, such as infrastructures are known as such.
  • EP2372322 notes that a reduction in the amount of cabling can be achieved by employing optic sensors for example, designed as Fiber Bragg Gratings disposed in a single optic fiber.
  • the optic sensors are, for example, designed as Fibre Bragg Gratings.
  • the cited document proposes to add to the support one or more temperature sensors for measuring temperature, and to use the temperature measurements to increase the accuracy of measurement results. It is a disadvantage that separate temperature sensor are required, which complicates the design.
  • a sensor module for load monitoring in an artifact that enables a compensation for temperatures while obviating separate sensors for measuring the temperature.
  • a sensor module is provided as claimed in claim 1.
  • the sensor module as claimed therein comprises an assembly of a carrier of an elastic material and at least a first and a second longitudinal optic fiber section with a first and a second fiber optic sensor element, and being mounted to the carrier in a first and a second mutually different directions at a respective pair of mutually opposite ends, the sensor module being configured to receive a load on a first load receiving side and to be restrained on at least a second side and the carrier being deformable by the received load in said a first and a second mutually different directions, resulting in a mutually different deformation of said at least a first and a second longitudinal optic fiber section so as to enable a computation of a temperature compensated magnitude of said load action based on respective corresponding optic response signals from said a first and a second fiber optic sensor element.
  • the fiber optic sensor elements This deformation is measurable by the fiber optic sensor elements as an optic response signal indicative for a longitudinal strain in case the fiber optic sensor element is a strain sensor element and as an optic response signal indicative for a longitudinal deformation in case the fiber optic sensor element is a deformation sensor element.
  • the fiber optic sensor element is an optical strain sensor element
  • the disclosure is however equally apphcable for a sensor module using optical deformation sensor elements.
  • the carrier in the assembly serves as a mechanical conversion means that converts the load into a respective longitudinal strain and/or longitudinal deformation of each of the longitudinal optic fiber sections.
  • the effect of the deformation of the carrier on the first and the second longitudinal optic fiber sections is different as they are arranged at mutually different angles in the carrier.
  • the carrier Upon receiving a mechanical load, the carrier will typically tend to be compressed in a direction determined by the load and the restriction(s) and to expand in directions wherein the carrier is unrestricted. Also temperature variations will typically result in deformations of the carrier and be measurable by the fiber optic sensor elements in the optic response signals as a (change of) longitudinal strain and or longitudinal deformation. However, contrary to the case of a deformation caused by a mechanical load, deformation in the carrier due to temperature variations will be more, though not necessarily fully, uniform deformation. Therewith, changes in strain in the first and the second
  • longitudinal optic fiber section due to temperature variations will be mutually related in a manner different from changes in strain in the first and the second longitudinal optic fiber section due load actions.
  • an estimated value of a load exerted on the sensor module which is compensated for temperature variations can be obtained from a combination of the first and second optic response signals.
  • a load compensated estimation of the temperature at the location of the sensor module can be obtained from another a combination of the first and second optic response signals.
  • one of the first and the second mutually different directions is selected as the direction wherein a load action causes a maximum compression of the carrier and the other one of the first and the second mutually different directions is selected as the direction wherein a load action causes a maximum expansion of the carrier.
  • these directions are substantially orthogonal with respect to each other.
  • an estimated value for an exerted load may be obtained for example as a difference of the strain values indicated by the optic response signals and an estimated value for a temperature may be obtained for example as a sum of the strain values indicated by the optic response signals.
  • a smaller difference in angle e.g. when the directions differ by 10 or 20 degrees may be sufficient to obtain optic response signals suitable for calculation of a temperature compensated estimation of the load and/or a load compensated estimation of the temperature.
  • Such a small angle may for example be contemplated if priority is given to other design characteristics.
  • a mode of mechanical conversion of a load exerted onto the loadable surface into a (change of magnitude of the) strain can be further determined in a way in which the carrier is restrained by the artifact in which it is embedded or by other means.
  • a load exerted on the elastic material causes the material to reduce in size in a direction of the load and to expand in directions wherein the carrier is left unrestrained.
  • the at least a first and a second longitudinal section, optionally arranged with space inside the carrier are protected by the latter.
  • the carrier may for example be manufactured of a rubber.
  • An elastic modulus of the rubber can be set at a desired value for a particular application by a proper composition of components and additives. For example in an application where the expected load is relatively low, e.g. a floor in a building the elastic modulus may be relatively low as compared to an application wherein the expected load is relatively high, e.g. a road provided for heavy traffic.
  • the at least a first and a second longitudinal optic fiber sections may be provided with a preset strain in the sensor module. In this way it can be avoided that a load needs to exceed a threshold before a strain occurs therein.
  • the at least a first and a second longitudinal optic fiber sections are formed by a common optic fiber.
  • longitudinal optic fiber section becomes available through that common optic fiber.
  • the carrier of the sensor module comprises a central portion in which the first and the second longitudinal optic fiber section are arranged at their respective pair of mutually opposite ends and the carrier additionally comprises at least one end portion having a size in a third direction transverse to the first and the second directions that is larger than a size of the central portion in the third direction.
  • This embodiment of the sensor module is advantageous in that it can be accommodated in various ways in the artifact to be monitored. In particular its construction makes it suitable to be
  • the at least one end portion of the sensor module aligned in this manner will be compressed in said third direction.
  • the end portion will expand in directions transverse to this third direction. In particular, it will expand in a direction in the plane defined by the first and the second direction and therewith deform the central portion in which the first and the second longitudinal optic fiber section are arranged.
  • the at least one end portion is provided at a side of the central portion near one of the mutually opposite ends of one of the respective pairs.
  • a difference between the effects of a deformation of the central portion on the at least a first and on the at least a second longitudinal optic fiber section are maximized.
  • a difference measurement would still be possible in other configurations, provided that a sufficient asymmetry is present between the orientation of the at least a first and the at least a second longitudinal optic fiber section with respect to the end portion.
  • the carrier further comprises a second end portion at a side of the central portion opposite the first end portion having a size of its dimension in the third direction that is larger than the size of the central portion in the third direction.
  • Both the sensor module comprising the thickened end portion(s) as described above and the sensor module not having one or two thickened end portions are applicable when they are arranged with their plane defined by the first and the second longitudinal optic fiber section transverse to a loadable surface of an artifact wherein they are embedded. Regardless the presence of having one or two thickened end portions, a load exerted on the loadable surface will induce mutually different deformations in the carrier in a direction
  • the sensor module may be provided as a separate element, for example as one of a plurality of separate elements.
  • a plurality of sensor modules may be integrated in a mat or strip.
  • a set of sensor modules may share a common optic fiber, for example in that the first and the second longitudinal optic fiber section of each of the sensor modules in the set of sensor modules are formed by that each are part of that common optic fiber.
  • a first common optic fiber may include the first longitudinal optic fiber section of each of the sensor modules and a second common optic fiber may include the second longitudinal optic fiber section of each of the sensor modules in the set.
  • a plurality of sensor modules are arranged in a grid in a plane parallel to that of a loadable surface of an application.
  • a first set of optic fibers may be arranged at distance from each other parallel to a first main direction in said plane, and a second set of optic fibers may be arranged at distance from each other parallel to a second main direction, transverse to said first main direction in said plane.
  • the optic fibers of the first set may include the at least one longitudinal sections of the sensor modules and the optic fibers of the second set may include the at least a second longitudinal sections of the sensor modules.
  • the carrier comprises an outer part and an inner part arranged within a central portion of the outer part, the inner part being of a material having a relatively high modulus of elasticity in comparison to that of the outer part, and providing for mechanical support of end portions of the at least a first and a second longitudinal optic fiber section.
  • the inner part may for example be of a polymer or a metal to provide for the relatively high modulus of elasticity. Alternatively a rubber having a relatively high modulus of elasticity may be used for this purpose.
  • the inner part provides for mechanical support of the at least a first and a second optic fiber section in that the at least a first and a second optic fiber section are included in a respective at least a first and a second sensor component that are supported by the inner part of the carrier.
  • the only difference between the first and the second sensor component is the orientation with which they are assembled in the carrier.
  • the only a single type of sensor component needs to be
  • At least one of said at least a first sensor component and a second sensor component comprises a frame that is fixed within said inner part and that has a first and a second mutually opposite sides, wherein the first and second mutually opposite sides are elastically connected by means of a resilient element.
  • the resilient element is provided to exert a longitudinal tension on the longitudinal optic fiber section of the sensor component and may be a pre tensioned resilient element so that a threshold in the response of the sensor module is avoided.
  • a first and a second resilient element mounting sections are provided extending in a direction from the first and second mutually opposite sides wherein at least one of the first and second resilient element mounting sections is movable with respect to the other resilient element mounting section.
  • the resilient element is fixed between the first and second mutually opposite sides. According to another one of these options the resilient element is fixed between the first and second resilient element mounting sections. According to again another one of these options the resilient element is fixed between the first or second mutually opposite sides and the first or second resilient element mounting sections.
  • the sensor module having the frame comprises a ring-shaped portion integral with, and having arranged therein said first and second resilient element mounting sections.
  • the ring shaped portion integral with, and having arranged therein the mounting sections provides for a robust, but flexible construction.
  • the frame with the ring shaped portion can be easily mounted within the support component, while still being capable to accurately follow its deformations, therewith allowing accurate measurements to be obtained with the optic strain sensor element.
  • the inner part of the sensor module may be left open in order to facilitate its deformation and therewith a detection of changes of load and/or temperature of the artifact wherein it is arranged.
  • a space left open in the inner part of the sensor module also facilitates an assembly of the carrier with the sensor components.
  • a remaining space inside the carrier may be filled with an inert fluid (such as a gel). Therewith ingress of potentially harmful substances in the substrate of the application can be avoided.
  • the frame may form a support component being of a material having a relatively high modulus of elasticity in comparison to that of the outer part.
  • the frame is molded from a polymer, and is mounted within such a support component. This is advantageous in that the support component can be of a relatively simple shape.
  • the frame being arranged within the support component can be of a relatively flexible, lightweight material.
  • the frame may be formed as a molded polymer object, which can be manufactured efficiently.
  • an optic sensor system including the optic sensor module is provided as claimed in claim 14.
  • an application of the optic sensor system is provided as claimed in claim 17.
  • FIG. 1, 1A schematically show an embodiment of a sensor module according to the first aspect of the invention, therein FIG. 1A shows a cross- section according to IA-IA in FIG. 1, FIG. IB illustrates some dimensions of the sensor module in said cross- section,
  • FIG. 2, 2 A schematically illustrate an embodiment of an optic sensor system according to the second aspect of the invention as wells as an embodiment of an application according to the third aspect of the invention, therein FIG. 2A shows a cross-section according to IIA-IIA in FIG. 2,
  • FIG. 3, 3A illustrate aspects pertaining to a use of a sensor module according to the first aspect, therein FIG. 3 illustrates some mechanical aspects, and FIG. 3A illustrates exemplary signals obtained from the sensor module,
  • FIG. 4 schematically shows an interrogator forming part of an embodiment of an optic sensor system according to the second aspect of the invention
  • FIG. 5 illustrates aspects pertaining to an alternative use of a sensor module according to the first aspect
  • FIG. 6A, 6B show another embodiment of a sensor module according to the first aspect of the invention, therein FIG. 6A shows the sensor module as an assembly and FIG. 6B shows an exploded view of the assembly,
  • FIG. 7 A, 7B shows a sensor component of the sensor module of FIG. 6A, 6B according to a first and a second perspective view
  • FIG. 8A, 8B show a part of the carrier of the sensor module in a
  • FIG. 9A, 9B show the sensor component of FIG. 7 A, 7B in more detail, therein FIG. 9A is a top view and FIG. 9B is a cross-section according to IXB-IXB of FIG. 9 A,
  • FIG. 10A, 10B show other aspects of the sensor component of FIG. 7 A, 7B in more detail, therein FIG. 10A is a top view and FIG. 10B is a cross-section according to XB-XB of FIG. 10A,
  • FIG. 11A, 11B, 11C show an example of an integrated set of sensor modules, therein FIG. 11A shows a pair of sensor modules in the integrated set of sensor modules, FIG. 11B shows the full integrated set of sensor modules and a further assembly element and FIG. 11C shows an example of a final product including the integrated set.
  • FIG. 11A shows a pair of sensor modules in the integrated set of sensor modules
  • FIG. 11B shows the full integrated set of sensor modules and a further assembly element
  • FIG. 11C shows an example of a final product including the integrated set.
  • FIG. 1, 1A schematically show an embodiment of a sensor module 1 according to the present invention.
  • FIG. 1A shows a cross-section according to IA-IA in FIG. 1.
  • the sensor module 1 comprises an assembly of a carrier 20 and at least a first and a second longitudinal optic fiber section 11a, l ib.
  • the a first and a second longitudinal optic fiber section 11a, l ib each have a proper fiber optic sensor element, indicated as first fiber optic sensor element 12a in the first longitudinal optic fiber section 11a second fiber optic sensor element 12b in the second longitudinal optic fiber section l ib.
  • the first longitudinal optic fiber section 11a is arranged inside the carrier 20 in a first direction x and mounted at mutually opposite ends 13al, 13a2 to the carrier, for example with an adhesive or using clamping means.
  • the second longitudinal optic fiber section l ib is arranged inside the carrier 20 and mounted at mutually opposite ends 13b 1, 13b2 to the carrier.
  • the fiber optic sensor elements 12a, 12b may be an optic strain-sensor element 12a, such as a fiber bragg grating (FBG) or another type of optic sensor element, e.g. an optic deformation sensor element, e.g. a Fabry-Perot type optic sensor element.
  • FBG fiber bragg grating
  • one or more additional optic strain-sensor elements may be provided within a same longitudinal section, for example to provide redundant sensor readings, for example to determine an average value of such readings that is more reliable than individual sensor readings.
  • one or more additional optic strain-sensor elements may serve as a back-up in the inadvertent case that the optic strain-sensor element 12a does not function properly.
  • the carrier 20 is deformable in a first and a second direction corresponding to the longitudinal directions of the longitudinal optic fiber sections 11a, l ib.
  • the longitudinal sections 11a and l ib are both longitudinal sections of a common optic fiber 10.
  • the optic fiber is guided outside the carrier 20 for example to a next sensor module.
  • the optic fiber may end at the second end 13b2 of the further longitudinal section lib.
  • the longitudinal sections 11a and l ib may be part of mutually different optic fibers.
  • the sensor module 1 is configured to receive a load action (F, see FIG. 3) on a first load receiving side, for example on a side formed by end portion 211.
  • the sensor module 1 is further configured to be restrained on at least a second side for example formed by end portion 212, differing from the first side such as to enable a deformation of the carrier 20 by the load action in the first and the second mutually different directions x, y, resulting in a mutually different deformation of the at least a first and a second longitudinal optic fiber section 11a, l ib.
  • These mutually different deformations enable a computation of a temperature compensated magnitude of said load action based on respective corresponding optic response signals from the first and second fiber optic sensor element.
  • FIG. IB schematically shows a cross-section Cl transverse to the longitudinal section 11a according to IB-IB in FIG. 1.
  • FIG. IB also schematically shows a cross-section C2 of the central portion 213 according to IA-IA in FIG. 1.
  • a circumference of the cross-section Cl is larger than a circumference of cross-section C2.
  • the cross-section Cl has a
  • the width wl, w2 of the end-portions 211, 212 and of the central portion 213 may be 15.5 cm and 9 cm respectively.
  • the difference in circumference is provided by a difference in thickness.
  • the thickness of the thickness dl, d2 of the end-portions 211, 212 and of the central portion 213 may be 3 and 2 cm respectively.
  • the carrier 20 comprises an outer part 210 and an inner part 220.
  • the latter is arranged within a central portion 213 of the outer part and is of a material that has a relatively high modulus of elasticity in comparison to that of the outer part.
  • the inner part 220 provides for mechanical support of end portions of the longitudinal sections 11a, l ib.
  • the inner part comprises a hollow cylindrical portion 221 definin an axis in a third direction z, transverse to directions x, y, a first pair of mutually opposite protrusions 222al, 222a2, and a second pair 222bl, 222b2 of mutually opposite protrusions.
  • the first and the second pair of protrusions point into a space defined by the hollow cylindrical portion 221.
  • Longitudinal section 11a of the optic fiber extends from a first one 13al of its mutually opposite ends through a first one 222al of the first pair of mutually opposite protrusions towards a second one 222a2 of the first pair of mutually opposite protrusions and through said second one to a second one 13a2 of its mutually opposite ends.
  • Longitudinal section l ib extends from a first one 1 lb 1 of its mutually opposite ends through a first one 222b 1 of the second pair of mutually opposite protrusions towards a second one 222b2 of the second pair of mutually opposite protrusions and through said second one to a second one l lb2 of its mutually opposite ends.
  • the inner part 220 may have a diameter in the range of a few cm to 10 or 20 cm, for example 8 cm, and the protrusions 222al, a2 may leave a space between them in the range of 1 mm to a few cm.
  • the space inside the carrier is filled with an inert liquid 240.
  • the inert liquid is for example a gel, that on the one hand allows a movement of the longitudinal sections 11a, l ib within the space, but that on the other hand dampens motions for protection thereof. The gel further mitigates digression of harmful substances into the space.
  • a sensor module 1 of FIG. 1 may have di ensions as specified in FIG. IB and FIG. 3. As illustrated therein the sensor module has a total height h (FIG. 3) a maximum width wl and a maximum thickness dl.
  • the total height h and the maximum width wl may be of the same order of magnitude, e.g. in the range of 10 to 20 cm. In this example the total height h and the maximum width wl respectively are 16 cm and 15.5 cm.
  • the maximum thickness dl may for example be in the order of a few cm, for example 3 cm.
  • FIG. 2, 2A shows an optic sensor system comprising an interrogator 40 and a sensor module 1 as presented in FIG. 1, 1A and IB.
  • the optic fiber 10 of the sensor module is coupled to the interrogator 40.
  • the interrogator 40 is configured to transmit an optical interrogation signal into the optic fiber, and to receive a response optical signal that has been modulated by the fiber optic sensor element 12a of the longitudinal optic fiber section 11a and by the further fiber optic sensor element 12b of the longitudinal optic fiber section 11a of the optic fiber 10.
  • the sensor module may be part of a series of sensor modules, one of which is illustrated by way of example as 1A in FIG. 2, 2 A.
  • Each sensor module may include a plurality of sensor elements in respective
  • the various sensor elements in the optic fiber 10 may have mutually different optical characteristics, for example mutually different characteristic wavelengths. Accordingly a change in strain of a particular longitudinal optic fiber section is detectable as a change in its associated unique characteristic wavelength. Also other optical properties may be used to modify the optical interrogation signal into a response signal, for example an amount of absorption.
  • the optic strain-sensor elements could have a same characteristic wavelength, but change the absorption of light in response to strain to a different extent.
  • the interrogator 40 may be coupled to additional optic fibers 10a, .. , 10n that may have similar sensor modules or other optic sensor modules.
  • the interrogator 40 may receive input signals from other types of sensors, such as cameras, acceleration sensors, acoustic sensors and the like. In the embodiment shown the interrogator 40 forwards output data to a wireless transmitter 70. Alternatively a wired connection may be used for this purpose, or the interrogator 40 may provide a storage space or a display means that enables an operator to access the output data.
  • the optic sensor system 1 is part of an application 500 wherein the sensor module is arranged within a
  • the artifact is a civil engineering asset
  • the civil engineering asset is a road 50 having a loadable surface 51 to support conveyance elements 92 of a vehicle 90.
  • Reference number 52 indicates a longitudinal direction of the road corresponding to direction z.
  • Other examples of civil engineering asset are a railway support, a bridge and a tunnel.
  • the sensor module 1 is arranged in an orientation wherein its third direction (z) is a direction in a plane that is (at least) substantially parallel (e.g. with a deviation of at most 10 degrees ) to a plane defined by the loadable surface 51.
  • the longitudinal section 11a is arranged in a direction that is at least substantially transverse to the loadable surface 51.
  • the carrier 20 of the sensor module 1 is provided with a reinforcement layer 230 at a side facing the loadable surface 51.
  • the reinforcement layer for example of a metal, e.g. stainless steel, may have a higher elasticity modulus than that of the first part 210 of the carrier 20 and serves to provide for a homogeneous load distribution.
  • FIG. 3 schematically shows how a load F imposed on the sensor module 1 causes a deformation of the carrier 20 and changes an amount of strain in the longitudinal sections 11a, l ib as schematically illustrated by the solid arrows and is detectable in detected response signals.
  • a load F is imposed on the sensor module 1, for example indirectly via the substrate of a road and a reinforcement layer 230, the strain in the longitudinal section 11a is reduced, due to a deformation of the carrier 20. This reduction in strain is detectable by optic strain-sensor element 12a.
  • the optic strain-sensor element 12a is an FBG element, its characteristic wavelength l ; will decrease as is
  • any of the optical response signals obtained from the optic strain sensor elements 12a, 12b is suitable to estimate a load F imposed on a loadable surface.
  • a change of temperature T may cause a change in strain values occurring in the longitudinal sections 11a, l ib due to a thermal expansion of the substrate of the road or of the carrier 20. These are schematically illustrated by the dashed arrows T. It has been found that an increase of temperature T tends to increase the strain in both longitudinal sections 11a, l ib, which is also detectable by the optical response signals obtained from the optic strain sensor elements 12a, 12b. As schematically illustrated by the dashed arrows in FIG. 3A, an increase in temperature T tends to result in an increase of the characteristic wavelengths Xa, b of both optic strain sensor elements 12a, 12b.
  • the optic sensor system may include an
  • the interrogator 40 shown therein includes a conversion module 41 for converting response optic signals from the respective fiber optic sensor elements 12a, 12b into respective magnitude signals S t2a, Si 2b indicative for a deformation or strain in the fiber optic sensor elements 12a, 12b.
  • the interrogator 40 further includes a first estim tion module 42 to estimate a load F imposed upon the loadable surface 51 from a difference between the first and the second magnitude as indicated by the magnitude signals S t2a, S i2t>.
  • the first estimation module 42 issues an output signal SF, indicative for the estimated value of the load F. Therewith deviations in the estimated load F due to temperature variations are at least mitigated.
  • the interrogator 40 further includes a second estimation module 43 to estimate a temperature prevailing within the sensor module 20 from a sum of the first and the second magnitude as indicated by the magnitude signals S i2a, Sia.
  • the second estimation module 43 to estimate a temperature prevailing within the sensor module 20 from a sum of the first and the second magnitude as indicated by the magnitude signals S i2a, Sia.
  • the calibration matrix can also be, in a further refinement, nonlinear.
  • a sensor module 1A may be provided wherein the longitudinal sections 11a, l ib are both at least
  • a third direction transverse to the directions of the longitudinal sections at least substantially (e.g. deviating by at most 10 degrees) coincides with a normal vector of the loadable surface, e.g. a surface 51 of a road 50.
  • a load imposed upon the carrier 20 causes it to deform, due to its elastic properties, which becomes datable as a change in optic response signals received for optic strain-sensor elements 12a, 12b.
  • a load F is imposed on the sensor module 20
  • the end portions 211, 212 are compressed, as illustrated by the arrows pointing inward in portions 211, 212.
  • the portions 211, 212 expand in transverse directions x, as indicated by the arrows pointing outward from portions 211, 212.
  • a strain in longitudinal section 11a is reduced.
  • the portions 211, 212 also expand in transverse directions z (not shown). As a result of this expansion, the strain in longitudinal section l ib is increased.
  • a temperature compensated estimation of the load F can be obtained by subtracting the sensor signals, for example with the circuitry of FIG. 4.
  • this circuitry can be used to estimate a temperature from a summation of the signals.
  • the sensor module 1A is configured to receive a load action on a first load receiving side, formed by the top faces of the end portions 211, 212 and to be restrained on at least a second side by the bottom faces of the end portions. This enables a deformation of the carrier 20 by the load action F in the first and the second mutually different directions (x, y). If for example only the left thickened end portion 211 is present, the carrier may be mechanically restrained at its right side to enable the deformation of the carrier 20 by the load action F in the first and the second mutually different directions (x, y).
  • FIG. 6 A shows an alternative embodiment of the sensor module 1, which is assembled from a carrier 20 and a first and a second component 250, 260 as schematically illustrated in the exploded view of FIG. 6B.
  • the carrier 20 comprises an outer part 210 and an inner part 220 arranged within the outer part.
  • the inner part 220 (See FIG. 8A, 8B) is manufactured of a material having a relatively high modulus of elasticity in comparison to that of the outer part 210 and provides for mechanical support of the end portions of the at least a first and a second optic fiber section. This may for example be achieved in that the outer part 210 is provided from rubber, and the inner part is provided from a metal, e.g. stainless steel.
  • the inner part provides for mechanical support of the at least a first and a second optic fiber section in that the at least a first and a second optic fiber section 11a, l ib are included in a respective at least a first and a second sensor component 250, 260, that are supported by the inner part of the carrier.
  • the first sensor component 250 with a first one of the longitudinal fiber optic sections and the second sensor component 260 with a second one of the longitudinal fiber optic sections can be readily assembled with the carrier 20.
  • the sensor components 250, 260 can be identical apart from their orientation in the assembly.
  • FIG. 7 A, 7A shows one of the optic sensor components, here component 250 in more detail from two different views.
  • the optic sensor component 250 comprises a frame 251having a first and a second mutually opposite sides 252a, 252b. The first and second mutually opposite sides 252a,
  • the sensor component 250 and likewise, the sensor component 260 snugly fit into the inner part 220 of the carrier 20.
  • FIG. 9A shows a top-view
  • FIG. 9B shows a cross-section according to IXB-IXB in FIG. 9A
  • the sensor component here to be used as the sensor component 250 including the first longitudinal optic fiber section 11a with fiber optic sensor 12a, comprises a frame 251 having a first and a second mutually opposite sides 252a, 252b.
  • the frame 251 can be easily and reliably assembled within the inner part 220 of the carrier, as illustrated in FIG. 6A.
  • FIG. 9A, 9B further show that the sensor component 250 includes a sensor mounting section 253, a pre-tensioned resilient element 256 and a resilient element mounting section 257 inside the frame 251.
  • the sensor mounting section 253 extends in a direction from the first side 252a to the second side 252b.
  • the sensor mounting section 253 has a first mounting portion 254 facing the first side 252a to mount a first end 13a 1 of the first longitudinal optic fiber section 11a, and a second mounting portion 255 facing the second side 252b to mount the second end 13a2 of the first longitudinal optic fiber section, opposite the first end 13al.
  • the second mounting portion 255 is movable with respect to the first mounting portion 254 and the resilient element 256 is fixed in a pre-tensioned manner between the second mounting portion 255 and the resilient element mounting section 257 at the second side 252b.
  • the resilient element 256 provides for a mechanical coupling while exerting a pretension to first longitudinal optic fiber section 11a.
  • the pre-tensioned resilient element provides for a way to define a strength of a mechanical coupling between the longitudinal optic fiber section to the carrier.
  • the mechanical coupling is determined by a stiffness of the resilient element k s on the one hand and a joint stiffness k t0t of the optic fiber and a stiffness determined by the movabihty of the second mounting portion 255 with respect to the first mounting portion 254 on the other hand.
  • the mechanical coupling M defined by these parameters is
  • the mechanical coupling may for example be selected in a range between 0.001 and 0.1. If the mechanical coupling is substantially stronger than 0.1, e.g. more than 0.5 this involves the risk of damage to the optic fiber. If the
  • mechanical coupling is substantially weaker than 0.001, e.g. less than 0.0001, the sensitivity is relatively low, involving the risk of an increased noise in
  • the second mounting portion 255 is U-shaped, having first and second legs 2551, 2552 facing the first and the second side respectively and protruding from the sensor mounting section 253.
  • the second mounting portion 255 has a mounting layer 2553 supported by the first and second legs.
  • the second end 13a2 of the first longitudinal optic fiber section and one end 2561 of the resilient element 256 are fixed to the mounting layer 2553.
  • the other end 2562 of the resilient element 256 is fixed to the resilient element mounting section 257.
  • the U-shaped constitution of the second mounting portion 255 provides for a relatively high flexibility along a longitudinal direction defined by said first and second side, while providing for a high stability in other directions.
  • the U-shaped second mounting portion 255 is arranged within side walls 2592-2594 of a tray shaped portion 259 of the sensor mounting section 253, and the first and second legs 2551, 2552 of the U-shaped second mounting portion 255 extend from a bottom 2591 of the tray shaped portion.
  • the U-shaped second mounting portion 255 has a very stable support, while requiring a modest amount of material.
  • a simple molding process requiring only a single pair of mold parts is enabled in that the bottom of the tray shaped portion is open below said mounting layer.
  • FIG. 11A - 11C illustrate a possible way of integrating sensor modules 1A, IB, etc into a strip 300.
  • FIG. 11A shows a portion of a strip with sensor modules 1A, IB, the first sensor module 1A comprising carrier 20A with sensor
  • the sensor modules 1A, IB, ... are integrated in the strip, but are mechanically decoupled by flexible bridge portions 310AB, that allow the sensor modules 1A,
  • the strip 300 may be provided with a protection plate 320 and bottom and top cover elements (FIG. 11C).
  • a common bottom cover element 340 is provided and a respective top cover element 330A, 330B, ..., 330H for each of the sensor modules 1A, IB, , 1H.
  • the mutually separate top cover elements 330A, 330B, ..., 330H enable the sensor modules to individually receive a load action on their first load receiving side.
  • the common bottom cover element 340 restrains all sensor modules 1A, IB, ... , 1H, in the array 300 on their second side such as to enable a deformation of the carrier 20 by the load action in both directions x, y.
  • the strip is configured to be arranged with the x-axis in a direction aligned with a loadable surface of an artifact (road, wall of a building etc) and with the y-direction transverse to the loadable surface.
  • the sensor modules 1A, IB, ..., 1H in the strip 300 are arranged to receive a load action in the y-direction.
  • the strip 300 may be packaged otherwise in order to enable its use when accommodated in a plane aligned with the loadable surface.
  • the strip 300 may be provided with a separate front cover element (not shown) for each of the sensor modules 1A, IB, ... , 1H.
  • the front cover elements are applied against the thickened end- portions 211A, 212A ... of each of the sensor modules 1A, IB, ... , 1H.
  • the mutually separate front cover elements enable the sensor modules to individually receive a load action in the direction of the z-axis
  • a common back cover plate 320 may be provided to restrain the sensor modules on the opposite side.
  • the load Upon application of a load on a cover plate, the load is transferred to the thickened end portions 211A, 212A of a sensor and causes a compression of these end portions in the z-direction. Due to this compression the end portions expand in directions x, y, transverse to the z direction, therewith also causing a deformation of the carrier 20 by the load action in both directions x, y.
  • the thickened portions 211A, 212A are optional.
  • the presence of the thickened portions 211A, 212A enables the strip 300 to be further used in an application in a manner aligned with the loadable surface of the artifact. Therewith a same product is suitable in both cases.
  • the sensor module disclosed herein comprises an assembly of a carrier of an elastic material and at least a first and a second longitudinal optic fiber section with a first and a second fiber optic sensor element.
  • the at least a first and a second longitudinal optic fiber section are mounted to the carrier in a first and a second mutually different directions at a respective pair of mutually opposite ends.
  • the sensor module is configured to receive a load on a first load receiving side and to be restrained on at least a second side.
  • a magnitude of said load action which is compensated for temperature can be computed from the corresponding optic response signals from the first and a second fiber optic sensor element.
  • rubber can be suitable in certain applications as an elastic material for use in the carrier, as its elastic modulus can easily be set at a desired value for a particular application by a proper composition of components and additives.
  • the elastic modulus may be relatively low.
  • the expected load is relatively high, e.g. a road provided for heavy traffic.
  • various other elastic materials such as wood, polymers, and metals are applicable for this purpose while achieving the same effect.
  • the carrier 20 and all the attached parts can be machined from various combinations of metals and polymers, with different thicknesses to achieve different rigidities as well as rehable operation in a wider range of temperatures.
  • combinations of elastic materials may be applied.
  • the carrier is provided with an outer part of rubber, and with an inner part of a polymer or of a metal, such as stainless steel or visa versa.
  • the sensor modules may be integrated in any other manner, for example in a mat comprising a two-dimensional array of sensor modules.
  • the sensor modules may be integrated through mechanical decoupling elements that allow relative movements between the sensor elements and the mat may be reinforced with cover plates. Separate cover plates may be provided for each sensor element on their load receiving side.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Length Measuring Devices By Optical Means (AREA)
  • Optical Transform (AREA)

Abstract

Le module de capteur (1) comprend un ensemble d'un support (20) d'un matériau élastique et d'au moins une première et une seconde section de fibre optique longitudinale (11a, lib) avec un premier et un second élément de capteur à fibre optique (12a, 12b). Les première et seconde sections de fibre optique longitudinale (11a, lib) sont montées sur le support dans une première et une seconde direction mutuellement différentes (x, y) au niveau d'une paire respective d'extrémités mutuellement opposées (13al, 13a2 ; 13b1, 13b2). Le module de capteur est conçu pour recevoir une action de charge sur un premier côté de réception de charge et pour être retenu sur au moins un second côté de façon à permettre une déformation du support (20) par l'action de charge dans lesdites première et seconde directions mutuellement différentes (x, y). Le module de capteur facilite une mesure compensée en température de l'action de charge.
PCT/NL2019/050260 2018-05-03 2019-05-02 Module de capteur pour surveillance de charge WO2019212348A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL2020870 2018-05-03
NL2020870A NL2020870B1 (en) 2018-05-03 2018-05-03 Sensor module for load monitoring

Publications (1)

Publication Number Publication Date
WO2019212348A1 true WO2019212348A1 (fr) 2019-11-07

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PCT/NL2019/050260 WO2019212348A1 (fr) 2018-05-03 2019-05-02 Module de capteur pour surveillance de charge

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NL (1) NL2020870B1 (fr)
WO (1) WO2019212348A1 (fr)

Cited By (1)

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RU2806404C1 (ru) * 2023-06-09 2023-10-31 Федеральное государственное бюджетное учреждение науки Пермский федеральный исследовательский центр Уральского отделения Российской академии наук (ПФИЦ УрО РАН) Способ определения упругих постоянных разномодульного материала

Citations (3)

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Publication number Priority date Publication date Assignee Title
WO2009056623A1 (fr) * 2007-10-31 2009-05-07 Shell Internationale Research Maatschappij B.V. Assemblage de capteurs de pression et procédé d'utilisation de l'assemblage
EP2372322A1 (fr) 2010-04-01 2011-10-05 Koninklijke BAM Groep N.V. Dispositif et procédé de déterminer la charge d'essieu d'un vehicule et une unité de détecteur
US8402834B1 (en) * 2010-02-12 2013-03-26 Intelligent Fiber Optic Systems, Inc. Fiber optic pressure sensor based on differential signaling

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009056623A1 (fr) * 2007-10-31 2009-05-07 Shell Internationale Research Maatschappij B.V. Assemblage de capteurs de pression et procédé d'utilisation de l'assemblage
US8402834B1 (en) * 2010-02-12 2013-03-26 Intelligent Fiber Optic Systems, Inc. Fiber optic pressure sensor based on differential signaling
EP2372322A1 (fr) 2010-04-01 2011-10-05 Koninklijke BAM Groep N.V. Dispositif et procédé de déterminer la charge d'essieu d'un vehicule et une unité de détecteur

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2806404C1 (ru) * 2023-06-09 2023-10-31 Федеральное государственное бюджетное учреждение науки Пермский федеральный исследовательский центр Уральского отделения Российской академии наук (ПФИЦ УрО РАН) Способ определения упругих постоянных разномодульного материала

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