A method and system for determining braking torque by detection performed by a photonic sensor at a fixed interface between a brake caliper body and respective supports

Abstract

A method and system for determining brake torque by detection performed by photonic sensors at fixed interfaces between a brake caliper body and a respective support is described. A method for determining brake torque B resulting from the actuation of a vehicle brake system by detection performed at at least one fixed interface (i, ii, iii, iv) between a brake caliper body 60 and a respective support 61 is described. The method first includes inserting at least one first washer device D into the at least one fixed interface, so that the washer device D is fixed and pressed between the brake caliper body 60 and the brake caliper support 61. Since the washer device D is susceptible to deformation when subjected to a force, a deformation and / or force S locally present at each point of the washer device D represents a force acting on the at least one fixed interface, depending on the brake torque B. The washer device D incorporates at least one deformation and / or strain sensor FBG at each detection location, positioned to detect deformation and / or strain representing three spatial vector components of the force acting on the washer device D when detected. The at least one deformation and / or strain sensor is a fiber optic strain sensor 2 of the fiber Bragg grating type. Next, the method comprises the steps of detecting a local deformation and / or strain S acting at a respective detection location by the at least one fiber optic strain sensor FBG and generating at least one respective photonic signal L indicative of the detected deformation and / or strain S, and then receiving the at least one first photonic signal L by an optical reading / interrogation unit 4 optically connected to the at least one fiber optic strain sensor 2 and generating at least one electrical signal E representative of the detected local deformation based on the received first photonic signal (L). Finally, the method comprises the step of determining a braking torque BT based on said at least one electrical signal E.Furthermore, a corresponding system for determining the brake torque BT, a washer device D adapted to operate in the execution of the aforementioned method, and a brake caliper with a sensor equipped to enable the execution of the aforementioned method are also described.

Description

Technical Field

[0001] The present invention relates to a method and a system for determining brake torque by detection performed using a photonic sensor (i.e., an optical fiber sensor) at a fixed interface between a brake caliper body and respective supports.

[0002] The present invention further relates to a brake caliper with a sensor equipped to enable implementation of the aforementioned method.

Background Art

[0003] In order to control, monitor, and operate a brake system such as an electronically controlled disc brake system, it is very useful to know as accurately as possible in real time the force or brake torque value applied by the brake caliper of the brake system during braking.

[0004] However, it is difficult to directly, accurately, and reliably measure the brake force and / or torque applied by the brake caliper of the brake system.

[0005] In this regard, known techniques tend to determine brake torque and / or brake force indirectly, but based on measurements examining quantities closely related to brake torque and / or force, such as forces acting on different points of the brake caliper.

[0006] On the other hand, it is necessary to take into account the need for an additional, as small and compact as possible sensor device that can be easily integrated into the brake system without causing functional problems.

[0007] In this regard, several compact sensor devices are known that can detect and / or measure the lateral (shearing) force acting between a brake caliper support and a vehicle hub using strain sensors.

[0008] However, such known devices are only capable of determining the braking force and / or torque based on the measurement of the lateral force being executed, with low accuracy and over a relatively limited range of measurable forces.

[0009] Furthermore, the results provided by such devices are not completely independent of the tightening torque of the screws used to fix the two components where the force is measured. In other words, the results are not independent of the axial force that constitutes a disturbance with respect to the accuracy of the estimation of the braking force and / or torque.

[0010] For these reasons, there is a need for a device and method for more accurately determining the braking torque and / or braking force by means of direct measurement performed at the interface between the brake caliper body and the brake caliper support, or between the brake caliper support and the hub.

[0011] For that purpose, with regard to fixed or floating caliper disc brakes, compactness, robustness, ease of installation (for example, using the fixing systems already provided for fixing the brake caliper), and versatility of use in the context of fixed or floating caliper disc brakes are further required of the measuring device.

[0012] As described above, the above requirements are not fully satisfied by the current solutions available from the prior art.

Summary of the Invention

[0013] An object of the present invention is to provide a method for determining the braking torque by means of detection performed by a photonic sensor at the fixed interface between the brake caliper body and each support, whereby, by referring to the prior art above, the above-mentioned drawbacks can be at least partially solved and the aforementioned needs particularly felt in the technical field of the object can be met.

[0014] This object and other objects are achieved by the method for detecting braking torque according to claim 1.

[0015] Some preferred embodiments of such a method are the subject matter of dependent claims 2 to 15.

[0016] A further object of the present invention is to provide a corresponding system for determining braking torque by detection performed by a photonic sensor at a fixed interface between a brake caliper body and respective supports.

[0017] This object is achieved by the process according to claim 25.

[0018] Some preferred embodiments of such a system are the subject matter of dependent claims 26 to 36.

[0019] A further object of the present invention is to provide a washer device for deformation and / or strain detection, which is included in the aforementioned system and can be used in the aforementioned method.

[0020] These and other objects are achieved by the device according to claim 16.

[0021] Some preferred embodiments of such a device are the subject matter of dependent claims 17 to 24.

[0022] A further object of the present invention is to provide a brake caliper with a sensor for a vehicle brake system, which is equipped to enable the execution of the aforementioned method.

[0023] These and other objects are achieved by the brake caliper with a sensor according to claim 37.

[0024] Some preferred embodiments of such a caliper are the subject matter of dependent claims 38 to 39.

[0025] A further object of the present invention is to provide a braking system that uses at least one of the aforementioned brake calipers with sensors or the aforementioned system to determine the braking torque.

[0026] These and other objects are achieved by the braking system according to claim 40.

[0027] Finally, an object of the present invention is to provide a method for manufacturing a washer device according to claims 16 to 24.

[0028] These and other objects are achieved by the manufacturing method according to claim 41.

[0029] Some preferred embodiments of such a manufacturing method are the subject matter of dependent claims 42 to 43. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Further features and advantages of the method and system according to the present invention will become apparent from the following description of its preferred embodiments, given by way of non-limiting example with reference to the accompanying drawings.

[0031]

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DETAILED DESCRIPTION OF THE INVENTION

[0032] Referring to FIGS. 1 to 14, a method for determining the braking torque BT resulting from the operation of a vehicle braking system by detection performed at at least one fixed interface (i, ii, iii, iv) between the brake caliper 60 and each support 61 (or, in another possible application, between the axle and the wheel suspension) will be described.

[0033] This method first includes the step of inserting at least one washer device D into the at least one fixed interface (i, ii, iii, iv), as a result of which the washer device D is fixed and pressed between the brake caliper body 60 and the brake caliper support 61, or between the brake caliper support 61 and the heads of the clamp elements 63, 64, or between the axle and the wheel suspension.

[0034] Since the washer device D undergoes deformation when subjected to force, the deformation and / or force S locally present at each point of the washer device D depends on the braking torque BT and represents the force acting on at least one fixed interface.

[0035] The above washer device D incorporates at least one deformation and / or strain sensor (FBG) at each detection position arranged to detect the deformation and / or strain representing the three spatial vector components of the force acting on the washer device D at the detection position.

[0036] At least one deformation and / or strain sensor (FBG) is an optical fiber strain sensor FBG of the fiber Bragg grating type.

[0037] Next, the method includes the steps of detecting, by each of the at least one optical fiber strain sensor FBG, the local deformation and / or strain S acting at each detection position, and generating each at least one photonic signal L representing the detected deformation and / or strain S.

[0038] Accordingly, the method provides that an optical reading / query unit 4 optically connected to the at least one optical fiber strain sensor 2 as described above receives the at least one photonic signal L as described above, and based on the at least one received photonic signal L, generates at least one first electrical signal E representing the detected local deformation and / or strain S by the optical reading / query unit.

[0039] Finally, the method includes the step of determining a braking torque BT based on the at least one electrical signal E representing the deformation and / or strain S as described above.

[0040] According to one embodiment of the method, the inserting step includes inserting a plurality of washer devices D1, D2, D3, D4 into respective fixed interfaces (i, ii, iii, iv), and each of such washer devices incorporates a plurality of deformation and / or strain sensors (FBG1, FBG2, FBG3, FBG4, FBG5, FBG6).

[0041] In this case, the determining step includes determining the braking torque BT based on a plurality of electrical signals Ejk derived from respective photonic signals Lj that represent respective deformations and / or strains Sij detected by respective fiber optic strain sensors. In the above notation, j is an index indicating one of the plurality of washer devices, and k is an index indicating one of the plurality of fiber optic strain sensors included in the washer device.

[0042] In different embodiments, any number of washer devices D can be used.

[0043] In some embodiments, each washer device D can include any number of fiber optic strain sensors FBG.

[0044] According to a preferred embodiment of this method, the determining step includes inserting a first washer device D1 into a first fixed interface (i) between the head of the first fixing bolt 63 and the first part of the brake caliper support 61, inserting a second washer device D2 into a second fixed interface (ii) between the head of the second fixing bolt 64 and the second part of the brake caliper support 61, inserting a third washer device D3 into a third fixed interface (iii) between the third part of the brake caliper support 61 and the caliper body 60, and inserting a fourth washer device D4 into a fourth fixed interface (iv) between the fourth part of the brake caliper support 61 and the caliper body 60.

[0045] According to different embodiments, this method can provide any combination of one, two, three, or four of the aforementioned washer devices, each in the respective manner shown above.

[0046] According to one embodiment of this method, one or more fiber optic strain sensors FBG are included in an optical fiber 14 arranged within a tangential peripheral band 13 of a washer device D. Further, each of the aforementioned fiber optic strain sensors FBG is obtained at each portion of the optical fiber inclined with respect to the radial surface of the washer (p) at an acute or obtuse inclination angle different from each value of 0°, 90°, 180°, 270°, and detects a strain S in a direction different from the normal direction and the tangential direction with respect to the washer. This detected strain S depends on both the normal component and the tangential component of the force acting on the sensor.

[0047] According to a preferred embodiment, this method includes a further step of incorporating at least one respective fiber optic temperature sensor 5 of the fiber Bragg grating type into at least one washer device D, then detecting, by means of at least one temperature sensor 5, the temperature value T present at each position, generating at least one respective auxiliary photonic signal Lt representing the measured temperature value T, then receiving, by an optical reading / implementation unit 4 optically connected to at least one temperature sensor 5, at least one auxiliary generated photonic signal Lt, and generating, by the optical reading / implementation unit 4, at least one auxiliary electrical signal Et representing temperature based on the at least one auxiliary received photonic signal Lt.

[0048] In this case, the step of determining includes processing the aforementioned at least one first electrical signal E and at least one electrical signal Et to obtain a measured value of the braking torque BT taking into account temperature compensation.

[0049] The aforementioned fiber Bragg grating optical sensor (hereinafter also referred to as "FBG sensor") is a type of deformation and / or strain sensor known per se.

[0050] FBG sensors are known to be very sensitive and widely applicable optical devices for measuring various physical parameters such as strain and temperature. In its simplest form, an FBG sensor is obtained by spatially periodic modulation of the refractive index inscribed in the core of an optical fiber (which can be obtained, for example, through the photosensitivity phenomenon or by using femtosecond optical pulses).

[0051] FBG sensors utilize

Number

Number

Number

[0052] The operating principle of an FBG sensor is based on the property that changes in the effective refractive index or grating pitch caused by external effects such as strain and temperature result in respective shifts

Number

Number

[0053] Here,

Number

Number

[0054] The Bragg wavelength shift depends linearly on the longitudinal strain ε with a sensitivity value of about 1.2 pm / με and the temperature change with a sensitivity value of about 11 pm / °C for a silicon fiber in the range of 1550 nm.

[0055] According to an embodiment, at least one of the aforementioned temperature sensors 5 includes a fiber Bragg grating fabricated with the same optical fiber 14, and at least one strain and / or deformation sensor FBG is fabricated.

[0056] FBG sensors are "passive" sensors. That is, they do not need to be powered, but are activated by illumination, for example, by transmitting optical generated radiation at an appropriate wavelength (e.g., the Bragg wavelength) in the optical fiber portion where the grating of the sensor is included. In response to this, the FBG sensor reflects or transmits an optical (i.e., photonic) signal. This depends on not only the incident radiation but also the strain conditions that the grating itself undergoes. Such photonic signals can be the transmitted optical signal (or optical spectrum) or the reflected optical signal (or optical spectrum) in different embodiments of the methods shown below.

[0057] According to an embodiment of this method (shown schematically in FIG. 1), the fiber optic strain sensor FBG is connected to the optical reading / query unit 4 by a first connecting optical fiber 31. Further, the optical reading / query unit 4 is configured to activate the aforementioned fiber optic strain sensor FBG by transmitting an optical activation radiation OA via the aforementioned first connecting optical fiber 31. A fiber Bragg grating type that reaches the optical reading / query unit 4 via the first connecting optical fiber 31.

[0058] According to another embodiment of this method (shown schematically in FIG. 2A), the fiber optic strain sensor FBG is connected to the optical reading / query unit 4 by a first input connecting optical fiber 32 and a second output connecting optical fiber 33. Further, the optical reading / query unit 4 is configured to activate the aforementioned fiber optic strain sensor 2 by transmitting an optical activation radiation OA via the first input connecting optical fiber 32. Further, the aforementioned photonic signal L includes an optical spectrum L transmitted by a fiber Bragg grating type strain sensor FBG, which reaches the optical reading / query unit 4 via the second connecting optical fiber 33.

[0059] According to the embodiment, each connection between each fiber from which a fiber Bragg grating type sensor is obtained and each connecting optical fiber to the optical reading / query unit is made by a fiber splice or a removable photonic connection element (optical connector).

[0060] According to an embodiment of this method, a plurality of fiber optic strain sensors FBG are provided and advantageously used.

[0061] In such an embodiment (shown in FIGS. 2A and 2B), each of the fiber optic strain sensors (FBG1, FBG2, FBG3, FBG4, FBG5, FBG6) of the device is made by a respective Bragg grating associated with a respective central operating wavelength (λ1, λ2, λ3, λ4, λ5, λ6).

[0062] In this case, the step of generating each at least one photonic signal includes generating a plurality of respective photonic signals (L1, L2, L3, L4, L5, L6). The step of receiving includes receiving the plurality of aforementioned photonic signals (L1, L2, L3, L4, L5, L6) by the optical reading / query unit 4. The step of generating at least one first electrical signal E includes generating a plurality of respective electrical signals (E1, E2, E3, E4, E5, E6) based on the plurality of received photonic signals (L1, L2, L3, L4, L5, L6). The step of processing includes processing the plurality of electrical signals (E1, E2, E3, E4, E5, E6) to obtain a measured value of the brake torque BT.

[0063] According to an embodiment, the method includes sending, by the optical reading / query element 4 via the connecting optical fiber 3, respective photoactivating radiations (OA1, OA2, OA3, OA4, OA5, OA6) at different respective operating wavelengths (λ1, λ2, λ3, λ4, λ5, λ6) to a plurality of strain and / or deformation sensors by wavelength division multiplexing (WDM) transmission technology. Next, the method includes receiving via the connecting optical fiber 3 and distinguishing, by using demultiplexing by wavelength division multiplexing (WDM) technology, each of the optical reflection spectra reflected by each of the respective optical spectra or the plurality of strain and / or deformation sensors (FBG1, FBG2, FBG3, FBG4, FBG5, FBG6). Here, each of the optical reflection spectra corresponds to a respective photonic signal (L1, L2, L3, L4, L5, L6).

[0064] According to an embodiment, each connection between each fiber from which a fiber Bragg grating type sensor is obtained and each connecting optical fiber to the optical reading / query unit is made by a fiber splice or a removable photonic connection element (optical connector).

[0065] According to an embodiment, this method includes, before the step of determining, a step of transmitting at least one of the aforementioned electrical signals E and / or auxiliary electrical signal Et to the control unit 20.

[0066] In this case, the step of determining includes calculating the braking torque BT by a processor of the control unit 20 by one or more algorithms executed by one or more software programs based on at least one of the aforementioned electrical signals E, or based on at least one of the aforementioned first electrical signals E and the auxiliary electrical signal Et, or based on the plurality of the aforementioned electrical signals (Ea, E1, E2, E3, E4, E5, E6; Eij) and at least one auxiliary electrical signal Et.

[0067] According to an embodiment of the method, the step of calculating includes calculating the braking torque BT by a predefined non-linear relationship between the braking torque and at least one deformation and / or strain detected by the strain sensor FBG at each position where the strain sensor FBG is incorporated into the washer device D.

[0068] Such a predefined non-linear relationship is represented by a computerized model or look-up table stored so as to be accessible by the processor of the control unit 20.

[0069] The aforementioned predefined non-linear relationship is determined by tests and / or performance evaluations and / or calibrations performed after at least one washer device D including at least one deformation and / or strain sensor D arranged and fixed at each fixed interface between the brake caliper body and the brake caliper support.

[0070] According to an embodiment of this method (as shown in FIG. 3A for example), the calculation step includes, for each of the four washer devices D1, D2, D3, D4, respective non-linear models NM1, NM2, NM3, NM4. The non-linear models are configured to determine three vector components of the respective vector forces acting on the washer devices F1, F2, F3, F4, i.e., three axes. Next, the braking torque BT is calculated based on the three-axis forces F1, F2, F3, F4 determined by the four non-linear models.

[0071] According to another embodiment of this method (as shown in FIG. 3B for example), the calculation step includes defining respective non-linear models NM1, NM2 for each of the two washer devices D1, D2 (or, similarly, any other combination of D1, D2, D3, D4 shown in FIGS. 9 and 10). The non-linear models NM1, NM2 are configured to determine three vector components of the respective vector forces acting on the washer devices F1, F2, i.e., three axes. Next, the braking torque BT is calculated based on the three-axis forces F1, F2 determined by the four non-linear models.

[0072] According to the embodiment, the step of defining the non-linear model of the washer device includes defining a basic non-linear model by means of a functional and / or structural simulation, for example, a calculation based on the finite element method (FEM), and then adjusting the parameters of the non-linear model by means of an initial calibration phase based on the strain measurement values Sij detected by the respective optical fiber strain sensors of the washer device and the simultaneous measurement values of the physical quantities that generate the strain Sij under known experimental conditions. The aforementioned physical quantities include, for example, the braking torque BT, the preload due to the tension of the fixing screws of the assembly V, and / or the pressure P applied by the brake caliper.

[0073] For example, in FEM simulations, a non - linear model of the relationship between strains measured at one or more points of the interface between the body and the brake caliper support, including adjustable parameters, can be provided. Next, a calibration operation is performed in the laboratory based on experimental measurements under known conditions of the pre - load of the screw tension and the brake caliper pressure. In this first step of calibration, in the laboratory, strain exists at one or more points of the interface between the body and the brake caliper support (by each washer device), and at one or more points of each washer device, and the brake torque generating such strain is measured. By the aforementioned measurements, the parameters of the basic non - linear model are adjusted, enabling an effective evaluation of the characteristics of the non - linear ratio between the detected strains and the brake torque that generated them.

[0074] By the aforementioned calculations and processes, a non - linear relationship between the strain measurement values and the brake torque at one or more points of the interface between the caliper body and the support can be defined, and thus the brake torque can be estimated based on the strain measurements performed.

[0075] According to one embodiment of this method, the processing step includes obtaining in real - time a dynamic measurement of the trend of the braking force and / or torque BT based on the time evolution of the detected deformation and / or strain.

[0076] Next, with reference to FIGS. 4 - 6, 7A, 7B, 8A, 8B, 8C, the deformation and / or strain detection washer device D will be described.

[0077] Such a washer device D comprises a device body 1 and an optical fiber 14 including one or more fiber Bragg grating (FBG) type strain sensors.

[0078] The device body 1 is shaped as a washer or a substantially disc-shaped plate that mainly extends along the radial reference plane p and has a first flat surface 11 and a second flat surface 12 parallel to the radial reference plane p. The first and second flat surfaces 11, 12 are arranged in close contact with the surfaces of the fixing means and / or the brake caliper support 61 and / or the brake caliper body 60, and can be attached to the fixing interfaces (i, ii, iii, iv) between the brake caliper body 60 and the brake caliper support 61, or between the brake caliper support 61 and the heads of the clamp elements 63, 64, or between the axle and the suspension of the vehicle wheel.

[0079] The washer body 1 is characterized by a peripheral band (and / or recess) 13 along the tangential direction that develops along a part or the periphery of the body 1 of the washer device D.

[0080] The washer body 1 is easily deformed when a force is applied. As a result, the deformation and / or force S locally present at each point of the washer device D represents the force acting on the washer device D.

[0081] The optical fiber 14 is arranged along the tangentially peripheral band 13 or is disposed in the tangentially peripheral band 13.

[0082] The optical fiber 14 includes one or more deformation and / or strain fiber Bragg grating optical fiber strain sensors (FBG), each of which acts at its respective detection position and is configured to obtain the local deformation and / or strain S that generates at least one respective photonic signal L representing the detected deformation and / or strain S.

[0083] Each of the aforementioned fiber optic strain sensors FBG is obtained from each portion of the optical fiber inclined with respect to the radial plane p at an acute or obtuse inclination angle different from each of the values of 0°, 90°, 180°, and 270°, and detects the strain S in a direction different from the normal direction, the tangential direction, and the tangential direction or the radial direction with respect to the reference plane p of the washer. The detected strain S depends on the normal component and the tangential component of the force acting on the sensor, and / or each of the three spatial vector components of the force acting on the sensor.

[0084] The optical fiber including the fiber optic strain sensor optical fiber FBG is configured to transmit the aforementioned at least one photon signal L generated by at least one fiber optic strain sensor FBG and receive at least one activation radiation OA directed to at least one fiber optic strain sensor FBG.

[0085] According to an embodiment, the optical fiber 14 is connected to the protection output tube 35, enabling the device to be connected to the optical reading / query unit 4.

[0086] According to an embodiment, the aforementioned inclination angle is within the range of ±30° to ±45°.

[0087] According to a preferred embodiment (for example, shown in FIG. 6), the aforementioned inclination angle is ±30°.

[0088] According to an embodiment of the device (for example, shown in FIG. 4), the aforementioned optical fiber includes a plurality of fiber optic strain sensors (FBG1, FBG2, FBG3, FBG4, FBG5, FBG6) arranged along the periphery of the optical fiber 14 and / or arranged at equal intervals and / or arranged at equal intervals.

[0089] Each of the fiber optic strain sensors (FBG1, FBG2, FBG3, FBG4, FBG5, FBG6) incorporated in the device D is made by respective Bragg gratings related to respective central operating wavelengths (λ1, λ2, λ3, λ4, λ5, λ6), and is excited by respective light emissions (belonging to the light emissions that give all energies in wavelength division multiplexing (WDM)) at respective wavelengths, and is configured to generate a spectrum of transmitted light or reflected light (the spectrum constituting the photonic signals (L1, L2, L3, L4, L5, L6)).

[0090] According to a preferred embodiment, the plurality of fiber optic strain sensors FBG described above include six fiber optic strain sensors (FBG1, FBG2, FBG3, FBG4, FBG5, FBG6).

[0091] According to an embodiment, the central operating wavelengths of the six aforementioned fiber optic strain sensors are 1535 nm, 1540 nm, 1545 nm, 1550 nm, 1555 nm, and 1560 nm.

[0092] According to an implementation example, each fiber optic strain sensor FBG has a grating with a length of 1 mm and a reflectivity of 50% or more. The six fiber optic strain sensors are arranged at equal intervals with a distance of 14 mm from each other.

[0093] According to an embodiment, the aforementioned optical fiber 14 further includes an optical fiber temperature sensor 5.

[0094] According to a possible embodiment, the shape of the main body of the washer device D and the material constituting the main body of the washer device D are selected according to the requirements for ensuring mechanical strength against axial fixed preload and shear force generated by the braking operation, and the requirements for optimizing the deformation of the main body of the washer device D without reaching the critical structural strain.

[0095] In particular, according to a preferred embodiment, the main body of the washer device D is made of steel, or titanium, or aluminum.

[0096] According to different embodiments, the washer device D can consist of various parts that are joined together and / or various parts that can be removed and reattached to each other. In particular, the body 1 of the washer device D can consist of various parts that are joined together and / or various parts that can be removed and reattached to each other.

[0097] According to a specific embodiment, the body of the washer device D is characterized by an elliptical cross-section depression 15 along an annular depression where an optical fiber including an optical fiber strain sensor is disposed, and a radial cavity 16 of the body of the washer device D. The cavities have the aforementioned elliptical depressions as their outer ends.

[0098] According to an embodiment, the periphery of the washer device D is characterized by two opposing straight sides and two opposing arcuate sides.

[0099] Figures 8A, 8B, and 8C show three specific design examples of the washer device D developed for devices of steel, titanium, and aluminum, respectively, using cross-sectional views. The aluminum washer in Figure 8C does not have an elliptical end cavity.

[0100] According to an embodiment of the washer device D, the first flat surface 11 and the second flat surface 12 of the device body 1 (washer-shaped or substantially disc-shaped plate) have surface changes that increase the friction between the first flat surface 11 and the second flat surface 12 and the surfaces of the fixing device and / or the brake caliper support 61 and / or the brake caliper body 60. The first flat surface 11 and the second flat surface 12 each come into contact with the surfaces of the fixing device and / or the brake caliper support 61 and / or the brake caliper body 60 in an operating state attached to the aforementioned fixing interfaces (i, ii, iii, iv).

[0101] The surfaces of the plane and the fixing device and / or the brake caliper support 61 and / or the brake caliper body 60, which are in contact with the aforementioned first and second flat surfaces respectively under the operating conditions to which they are attached. One of the aforementioned fixing interfaces (i, ii, iii, iv).

[0102] According to an example of the aforementioned embodiment, the aforementioned surface change of the flat surface is obtained by a mechanical process known per se, such as knurling.

[0103] According to another example of the aforementioned embodiment, the aforementioned surface modification of the flat surface is obtained by "texturing" the surface made by laser technology or equivalent known methods applicable to any metal surface such as steel, titanium, aluminum, etc.

[0104] According to another example of the aforementioned embodiment, the aforementioned surface modification of the flat surface is obtained by coating. In this regard, diamond particles, silicon carbide SiC embedded in electrolytic nickel, or deposition of aluminum oxide or other various methods can be used when the substrate is aluminum.

[0105] According to some possible examples, the aforementioned surface change of the plane is obtained by finishing by mechanical removal, machining by local deformation of the material (upsetting, knurling), laser removal (or machining) that vaporizes, melts or burns the material, or various possible coating techniques (coating techniques based on extremely hard nanoparticles by nanotechnology that generate high-friction hard inclusions on the surface to affect the surface so as to create a local "grip" as a result of large-force contact points).

[0106] It is worth noting that the above-described embodiment enables an increase in the friction between the sensor and the caliper body or the brake caliper support. As described above, this is particularly advantageous in that, in the invention of the present application, the force acting on the washer device determines the deformation of the body of such a washer device and determines the influence detected by the FBG sensor.

[0107] In particular, the effect of this embodiment is to eliminate or significantly reduce the phenomenon of local variations in strain due to the reversal of vehicle motion. In fact, the measures taken increase the coefficient of friction at the interface. By doing so, it is possible to avoid or significantly reduce these minute settings that change the local frictional conditions with the change between the forward and reverse directions, and as a result, change the distribution of strain on the surface of the body of the washer device. This is very important. Because every time the direction of the vehicle changes, the local state changes, the deformation of the washer is different, the reproducibility of the output characteristics of the sensor is low, and it becomes non-linear. On the other hand, due to the aforementioned characteristics of the present embodiment, the effects induced by the braking torque on the sensitive elements between the forward and reverse conditions are standardized and decisive, and thus the reproducibility and linearity of the sensor output characteristics are improved.

[0108] With reference to FIGS. 1 to 14, a system 100 for determining the braking torque BT resulting from the operation of a vehicle braking system by detection performed at at least one fixed interface (i, ii, iii, iv) between the brake caliper body 60 and each support 61, between the brake caliper support 61 and the heads of the clamp elements 63, 64, or between the axle and the wheel suspension will be described.

[0109] The system 100 comprises at least a washer device D, an optical reading / query unit 4, and a remote control unit 20 according to any of the above-described embodiments.

[0110] At least one washer device D is fixed and pressed to at least one of the respective fixed interfaces (i, ii, iii, iv) between the brake caliper body 60 and the brake caliper support 61, between the brake caliper support 61 and the clamp element heads 63, 64, or between the axle and the wheel suspension.

[0111] The optical reading / query unit 4 is optically connected to at least one washer device D and receives the at least one photonic signal L described above. The optical reading / query unit 4 is configured to generate at least one electrical signal E representing the detected deformation and / or strain S based on the at least one received first photonic signal L.

[0112] The remote control unit 20 is connected to the optical reading / query unit 4 so as to receive the at least one first electrical signal E described above, and is configured to process the at least one first electrical signal E representing the deformation and / or strain S to provide a measured value of the brake torque BT.

[0113] For example, according to one embodiment shown in FIGS. 3A and 3B and having four and two washer devices respectively, the system has a plurality of washer devices (D1, D2, D3, D4) at each of the respective fixed interfaces (i, ii, iii, iv).

[0114] According to an example, each of the washer devices described above incorporates a plurality of deformation and / or strain sensors (FBG1, FBG2, FBG3, FBG4, FBG5, FBG6).

[0115] In this case, the remote control unit 20 is configured to determine the braking torque BT based on a plurality of electrical signals Ejk resulting from respective photonic signals Lj that represent respective deformations and / or strains Sij detected by respective optical strain sensors. In the notation used herein, j is an index indicating one of the plurality of washer devices, and k is an index indicating one of the plurality of optical fiber strain sensors included in the washer device.

[0116] According to a preferred embodiment (shown in FIG. 3 as far as the functional aspect is concerned and in FIGS. 7 and 8 as far as the structural aspect is concerned), the system includes (i) a first washer device D1 at a first fixed interface between the head of the first fixed bolt 63 and the first part of the brake caliper support 61, (ii) a second washer device D2 of the first fixed interface between the head of the second fixed bolt 64 and the second part of the brake caliper support 61, (iii) a third washer device D3 of the third fixed interface between the third part of the brake caliper support 61 and the caliper body 60, and (iv) a fourth washer device D4 at the fourth fixed interface between the fourth part of the brake caliper support 61 and the caliper body 60.

[0117] According to an embodiment (for example, the embodiment shown in FIGS. 4, 5, 6A, and 6B), one or more optical fiber strain sensors FBG are included in an optical fiber 14 disposed within a circumferential band 13 in the tangential direction of the washer device.

[0118] Each such optical fiber strain sensor FBG is obtained at each part of the optical fiber inclined with respect to the radial plane of the washer p (for example, the plane of the cross-section in FIGS. 8A, 8B, and 8C) at an acute or obtuse inclination angle different from each value of 0°, 90°, 180°, and 270°, and detects a strain S in a direction different from the normal direction and the tangential direction with respect to the washer. The detected strain S depends on both the normal component and the tangential component of the force acting on the sensor.

[0119] According to one embodiment (for example, the embodiment shown in FIG. 2), the system includes at least one respective fiber optic temperature sensor 5 of the fiber Bragg grating type incorporated in at least one washer device D.

[0120] Each of the at least one temperature sensor 5 is configured to detect the temperature value T present at each location and generate at least one respective auxiliary photonic signal Lt representing the measured temperature value T.

[0121] In this case, the optical reading / query unit 4 is optically connected to at least one temperature sensor 5, receives at least one generated auxiliary photonic signal Lt, and is configured to generate at least one auxiliary electrical signal Et based on the at least one received auxiliary photonic signal Lt.

[0122] In this case, the remote control unit 20 is configured to process at least one first electrical signal E and at least one auxiliary electrical signal Et to obtain a measured value of the braking force BT taking into account temperature compensation.

[0123] According to an example of the system, the aforementioned at least one temperature sensor 5 comprises a fiber Bragg grating made in the same optical fiber 14 in which at least one strain and / or deformation sensor FBG is made.

[0124] According to an embodiment of the system (for example, the embodiment shown in FIG. 1), the fiber optic strain sensor FBG is connected to the optical reading / query unit 4 by a first connecting optical fiber 31.

[0125] In this case, the optical reading / query unit 4 is configured to activate the fiber optic temperature sensor by transmitting an optically activating radiation OA via the first connecting optical fiber 31, and the second photonic signal L includes the optical spectrum L reflected by the temperature sensor FBG, which reaches the optical reading / query unit 4 via the first connecting optical fiber 31.

[0126] According to another embodiment (for example, the embodiment shown in FIG. 2), the fiber optic strain sensor FBG is connected to the optical reading / query unit 4 by the first input connection optical fiber 32 and the second output connection optical fiber 33.

[0127] In this case, the optical reading / query unit 4 is configured to activate the aforementioned fiber optic temperature sensor FBG that transmits the optical activation radiation OA via the first input connection optical fiber 32, and the second photonic signal L includes the second optical spectrum L transmitted by the fiber Bragg grating type temperature sensor FBG, which reaches the optical reading / query unit 4 via the second output connection optical fiber 33.

[0128] According to another embodiment of the system (the embodiment shown in FIG. 2), each of the fiber optic strain sensors (FBG1, FBG2, FBG3, FBG4, FBG5, FBG6) of the device is made by a Bragg grating related to the central operating wavelength (λ1, λ2, λ3, λ4, λ5, λ6).

[0129] Each of the fiber optic strain sensors (FBG1, FBG2, FBG3, FBG4, FBG5, FBG6) is configured to generate at least one of each of the plurality of photonic signals (L1, L2, L3, L4, L5, L6).

[0130] The optical reading / query unit 4 is configured to receive the plurality of photonic signals (L1, L2, L3, L4, L5, L6) and generate at least one of each of the plurality of electrical signals (E1, E2, E3, E4, E5, E6)) based on the plurality of received photonic signals (L1, L2, L3, L4, L5, L6).

[0131] The remote control unit 20 is configured to process the aforementioned plurality of electrical signals (E1, E2, E3, E4, E5, E6) to obtain a measured value of the brake torque BT.

[0132] According to an embodiment, the optical reading / query unit 4 transmits each of the respective photoactivating radiations (OA1, OA2, OA3, OA4, OA5, OA6) to a plurality of deformation and / or strain elements via the connecting optical fiber 3 at respective different operating wavelengths (λ1, λ2, λ3, λ4, λ5, λ6) by wavelength division multiplexing (WDM) transmission technology, receives them via the connecting optical fiber 3, and distinguishes each optical spectrum reflected by each of the plurality of deformation and / or strain sensors (FBG1, FBG2, FBG3, FBG4, FBG5, FBG6) (each optical reflection spectrum corresponds to a respective photonic signal (L1, L2, L3, L4, L5, L6)) by demultiplexing using multi-wavelength division multiplexing (WDRD) technology.

[0133] According to one embodiment of the system, the control unit 20 has a processor configured to calculate the braking torque BT by one or more algorithms executed by one or more software programs based on at least one of the aforementioned electrical signals E, or based on at least one of the aforementioned electrical signals E and the auxiliary electrical signal Et, or based on a signal based on the plurality of aforementioned electrical signals (Ea, E1, E2, E3, E4, E5, E6; Eij) and at least one of the aforementioned auxiliary electrical signals Et.

[0134] According to different embodiments of the system, the remote control unit 20 is configured to determine the braking torque BT according to the aforementioned algorithms and / or procedures of the method according to the present invention based on the electrical signal E representing the detected strain S. Invention.

[0135] With reference to FIGS. 12 to 14, further exemplary details related to the reading / query unit 4 will be described.

[0136] According to an embodiment of the system 100, the optical reading / query unit 4 includes a broadband optical radiation source 40, an optical circulator 46, and an optoelectronic spectrometer receiver 41.

[0137] The broadband light source 40 is configured to transmit a first activation light emission OA or a plurality of second activation light emissions OAa, OAb, OAc and / or a second activation light emission OAt.

[0138] The photoelectron spectrometer receiver 41 is configured to select one wavelength and / or a plurality of wavelengths to receive, and also receive the aforementioned first photonic signal L or the aforementioned plurality of first photonic signals La, Lb, Lc, and convert them into a first electrical signal E or a plurality of first electrical signals Ea, Eb, Ec, and / or receive the aforementioned second photonic signal Lt and convert it into a second electrical signal Et.

[0139] In this embodiment, (as shown in FIG. 12) the multiplexed FBG sensors in the wavelength region (WDND) are interrogated using a wide-area spectrum source and spectrometer-based technology.

[0140] The wide-area spectrum light source includes, for example, a superluminescent diode or a spontaneous light source (such as a semiconductor optical amplifier or an erbium-doped optical fiber amplifier), and is used to illuminate the FBG sensors 2a, 2b, 2c that have peak reflectivities at different wavelengths (λa, λb, λc) that do not overlap with each other (through the input port and through).

[0141] (In the example shown in FIG. 12) The photonic signals La, Lb, Lc with different wavelengths are retroreflected by the FBG sensors and coupled to the spectrometer 41 through the output port of the optical circulator 46.

[0142] The spectrometer 41 is, for example, a dispersion element typically made by a phase grating volume that can spatially separate different spectral components of the signal. Such spatially separated signal components are coupled to an optical receiver array that can generate signals with intensity values corresponding to various wavelengths.

[0143] Each optical receiver is sensitive to optical emissions corresponding to a clearly defined spectral region and can reconstruct the entire spectrum within the target spectral range.

[0144] According to another embodiment of the system 100 (shown in FIG. 13), the optical reading / query unit 4 comprises an adjustable optical radiation source 42, an optical circulator 46, and a photodiode optoelectronic receiver 43.

[0145] The adjustable optical radiation source 42 is configured to transmit a desired optical emission OAn (at respective wavelengths λn) between possible first photoactivating radiations OAa, OAb, OAc or a second photoactivating radiation OAt at a given wavelength λt and at a given time.

[0146] The emitted optical emission OAn irradiates an optical fiber including FBG sensors (via the input port and the through port of the optical circulator 46), determines the response by the FBG sensors sensitive to wavelength λ1, which generates a direct reflection photonic signal Ln, which is coupled to the photodiode receiver 43 via the output port of the optical circulator 46.

[0147] The photodiode optoelectronic receiver 43 is configured to receive the first photonic signal Ln and convert it into a first electrical signal En (or to receive a second photonic signal Lt and convert it into the second electrical signal Et).

[0148] In this embodiment, wavelength division multiplexing (WDM) FBG sensors are interrogated using wavelength tunable laser and photodiode-based technology.

[0149] According to various embodiments, the adjustable optical radiation source 42 is an adjustable laser used in a known "agile adjustable" or "swept wavelength" mode.

[0150] According to another embodiment of the system 100 (schematically shown in FIG. 14), the optical reading / query unit 4 is entirely made by a single photonic integrated circuit using PIC technology. In this case, such a single integrated photonic circuit includes a broadband optical radiation source 40, at least one wavelength optical filtering element 44, and a optoelectronic photodiode receiver 43.

[0151] The broadband optical radiation source 40 is configured to transmit a first activation optical radiation OA or a plurality of second activation optical radiations OAa, OAb, OAc and / or a second activation optical radiation OAt.

[0152] The optical radiations emitted through the input port and the through port of the optical circulator 46 (including the optical radiations OAa, OAb, OAc in the example of FIG. 14) irradiate optical fibers each including an FBG sensor. The FBG sensors reflect respective photonic signals La, Lb, Lc. The WDM photonic signal is given by the sum of the signals La, Lb, Lc as a whole at its different wavelengths and is transmitted to the input of the filter optical element 44 through the output port of the optical circulator 46.

[0153] To select each photonic signal (the photonic signal Lb with wavelength λb in the example of FIG. 14), at least one wavelength optical filtering element 44 can be adjusted around the wavelength of the interrogated fiber Bragg grating. The adjustable optical filtering element 44 can be adjusted to different wavelengths to select, according to desire, in sequence or at different times, the photonic signal reflected by one of the FBG sensors, the photonic signal reflected by one of the FBG sensors.

[0154] The optoelectronic photodiode 43 receiver is configured to receive the photonic signal selected from among the aforementioned photonic signals and convert it into one or more electrical signals, and / or, if selected, to receive a second photonic signal Lt and convert it into a second electrical signal Et.

[0155] The sensor-equipped brake caliper 6 for a vehicle brake system is described below with reference to FIGS. 9, 10, and 11.

[0156] The sensor-equipped brake caliper 6 includes a brake caliper body 60, a brake caliper support 61, a first fixing bolt 63 and a second fixing bolt 64, and at least one washer device D according to any of the above embodiments.

[0157] At least one washer device D is fixed or held between the brake caliper body 60 and the brake caliper support 61 at at least one fixing interface (i, ii, iii, iv) between the brake caliper body 60 and the brake caliper support 61.

[0158] According to various embodiments, the brake caliper is a fixed or floating brake caliper.

[0159] According to an embodiment, the sensor-equipped caliper 6 further includes an optical reading / query unit 4 that can be connected to a remote control unit 20 outside the brake caliper.

[0160] The optical reading / query unit 4 is as described above.

[0161] In particular, the optical reading / query unit 4 is optically connected to the first photonic connection means 3 to receive at least one photonic signal L, and is configured to determine at least one electrical signal E representing the detected deformation and / or strain S based on the at least one received photonic signal L. The aforementioned at least one electrical signal E is adapted to be transmitted to the remote control unit 20.

[0162] According to a preferred embodiment, the brake caliper 6 with sensors includes: (i) a washer device D1 at a first fixed interface between the head of the first fixed bolt 63 and the first part of the brake caliper support 61; (ii) a second washer device D2 at a first fixed interface between the head of the second fixed bolt 64 and the second part of the brake caliper support 6; (iii) a third washer device D3 at a third fixed interface between the third part of the brake caliper support 61 and the caliper body 60; and (iv) a fourth washer device D4 at a fourth fixed interface between the fourth part of the brake caliper support 61 and the caliper body 60.

[0163] In various possible embodiments, the brake caliper is a fixed or floating disk brake caliper, a caliper with radial and axial connections, a monoblock or floating caliper, or a hydraulic or electric caliper.

[0164] As described above, the optical reading / query unit 4 is integrated and / or housed in the caliper 6 with sensors. In this case, the electrical signal E is output from the caliper with sensors and directed to the remote control unit.

[0165] According to another embodiment of the system, the optical reading / query unit 4 is external to the brake caliper 6 with sensors. In this case, the photonic signal L is emitted from the caliper with sensors and sent through an optical fiber towards the optical reading / query unit.

[0166] According to an embodiment, the brake caliper with sensors comprises a washer device positioning element 62 adapted to hold and arrange one or more washer devices D in the correct positions.

[0167] Referring to FIG. 11, details regarding the relationship between the brake torque, the force acting on the washer device, and the force acting on the optical fiber strain sensor are shown here.

[0168] When braking torque is applied to the brake rotor, a mechanical action opposite to the braking torque is applied from the connection part of the brake caliper body. Therefore, the interaction of these actions is applied to the hub. The aforementioned mechanical action can be represented by the force and moment acting on the support interface. The interface between the brake caliper and the hub bolt (i.e., between a part of the brake caliper body and a part of the brake caliper support) is defined as (i), (ii), (iii), (iv) as described above, as shown in FIGS. 10 and 11.

[0169] Considering the x, y, z coordinates shown in FIG. 11 and the interfaces (i), (ii), (iii), (iv), the following quantities can be defined.

[0170] Fn-iii and Fn-iv are the vertical reaction forces exchanged between the brake caliper and the brake caliper support, due to the action of bolts 63 and 64 respectively. Fn-i and Fn-ii are the vertical reaction forces exchanged between the head of each bolt and the brake caliper support. Furthermore, the moments of torque in the zy plane (Mz-i, Mz-ii, Mz-iii, Mz-iv, My-i, My-ii, My-iii, My-iv) are generated by the vertical reaction force distribution at each contact interface.

[0171] Finally, the moments of torque along the x direction (Mx-i, Mx-ii, Mx-iii, Mx-iv) and the forces in the zy plane (Fz-i, Fz-ii, Fz-iii, Fz-iv, Fy-i, Fy-ii, Fy-iii, Fy-iv) are due to the frictional interaction between the caliper contact surface, the brake caliper support, and the bolt head.

[0172] The sum of the torque contributions of each of the aforementioned frictions with respect to the wheel axle represents the braking torque reaction action.

[0173] The present invention also encompasses a vehicle brake system including a plurality of brake calipers 6 with sensors according to any one of the above-described embodiments of the caliper with sensors.

[0174] The present invention further includes a vehicle braking system including a system 100 for determining a braking torque BT resulting from the implementation of a vehicle braking system according to any one of the embodiments for determining the above braking torque BT.

[0175] The present invention further includes a method for manufacturing the washer device D of the above-described embodiment.

[0176] Such a manufacturing method includes the steps of arranging an optical fiber 14 prepared in advance by inscribing fiber Bragg gratings (FBGs) arranged at predetermined intervals on the side surface of the washer of the washer device D, arranging each part of the fiber inscribed by each strain sensor FBG along the side surface of the washer at a predetermined inclination angle with respect to a reference plane p in the radial direction of the washer in each inclination direction, fixing the formed box to the washer and the optical fiber to protect and direct the outgoing fiber, fixing the optical fiber 14 and its inclined fiber part including the fiber Bragg grating strain sensor FBG with a binder material on the side band of the washer and within the output box, and providing a protective layer around the peripheral side band of the washer where the optical fiber 14 is arranged.

[0177] According to another embodiment, the aforementioned manufacturing method includes a further step of modifying the first flat surface 11 and the second flat surface 12 of the device body 1 by a surface modification adapted to increase the friction between the first flat surface and the second flat surface in the operating state of the fixing device and / or the support portion of the brake caliper 61 and / or the aforementioned first flat surface and the second flat surface of the brake caliper body 60 attached to the fixed interfaces (i, ii, iii, iv).

[0178] According to different possible examples, the aforementioned surface modification of the first flat surface 11 and the second flat surface 12 is performed by mechanically processing the surface, for example, by knurling or "texturing" the surface using laser technology or the like, or by a surface coating.

[0179] It is worth noting that the object of the present invention is fully achieved by the above-described method and system due to its functional and structural features.

[0180] In fact, the above-described detection washer device can accurately detect the deformation and / or forces (these forces depend on the braking torque) acting on the clamping interface between the brake caliper body and its support, and / or between the brake caliper support and the vehicle axle. In particular, the detection washer device can detect both the tangential component and the normal component of the force acting on it (or, more specifically, three vector components).

[0181] Furthermore, due to its small size and its "washer" shape, such a device can be advantageously and easily inserted between the wheel device and the vehicle axle (in particular, between the brake caliper and the brake caliper support) using the fixing means already provided (for example, the screws already provided for attaching the brake caliper to its support, one or more attachment points).

[0182] As shown above, there are many possible arrangements of the device with respect to the brake caliper. This greatly improves the diversity of use and enables various structural options. Also, for example, degrees of freedom are provided to achieve different levels of accuracy according to requirements, such as a solution with multiple devices arranged at different positions. A solution with multiple optical fiber sensors provides more detections and respective electrical signals to the control system, enabling more accurate processing and estimation.

[0183] Other advantages of the device according to the present invention are compactness, robustness, ease of installation (for example, using the fixing system already provided for fixing the brake caliper), the diversity of use in different points and / or splices and / or joints of such a system, and in the situation of fixed or floating caliper disc brakes.

[0184] In addition to the aforementioned advantages, there are also advantages that specifically stem from the use of fiber optic sensors.

[0185] Thanks to the above-described system and method, similar advantages are achieved.

[0186] This system comprises one or more sensor-equipped brake calipers that include fiber optic sensors optically connected to a reading / query unit (which can also be integrated into a remote or the brake caliper), for the optoelectronic conversion of strain information, which can advantageously also be based on WDM technology.

[0187] The reading / query unit can be created based on various electro-optic technologies.

[0188] Advantageously, such a reading / query unit can be fabricated by silicon-based photonic technologies (e.g., PIC: Photonics Integrated Circuit), and such a unit can also be fabricated by integrating it into a sensor-equipped brake caliper.

[0189] Thus, the control unit of the system can use temperature compensation to determine the brake torque over a wide operating range.

[0190] (For example, because various washer detectors, each including multiple sensors, can be used very flexibly), the ability to detect strain at multiple points, although indirect, helps to more accurately determine the brake torque.

[0191] Those skilled in the art can make many changes and adaptations to the above-described embodiments, or replace them with other functionally equivalent elements to meet incidental needs without departing from the scope of the appended claims. All the features described above as belonging to one possible embodiment can be implemented independently of the other described embodiments.

Claims

1. A method for determining a braking torque (BT) resulting from the operation of a vehicle's braking system by detection performed at at least one fixed interface between a brake caliper body (60) and respective brake caliper supports (61), or between an axle and a wheel suspension, the method comprising: The method further comprises: Inserting at least one washer device (D) into the at least one fixed interface, the at least one washer device (D) being fixed and pressed between the brake caliper body (60) and the brake caliper support (61), or between the brake caliper support (61) and the head of a clamping element, or between the axle and the wheel suspension; The at least one washer device (D) deforms when subjected to a force; The deformation and / or strain (S) locally present in the at least one washer device (D) represents the force acting on the at least one fixed interface and depends on the braking torque (BT); The at least one washer device (D) incorporates at least one deformation and / or strain sensor (FBG) at a detection location; The at least one deformation and / or strain sensor (FBG) is arranged to detect deformation and / or strain representing three spatial vector components of the force acting on the at least one washer device (D) at the detection location; The at least one deformation and / or strain sensor (FBG) is a fiber Bragg grating type optical fiber strain sensor; The method further comprises: Detecting, by the optical fiber strain sensor, the deformation and / or strain (S) occurring at the detection location and generating at least one photonic signal (L) representative of the deformation and / or strain (S); Receiving, by an optical reading / interrogation unit (4) optically connected to the optical fiber strain sensor, the at least one photonic signal (L); Generating, by the optical reading / interrogation unit (4), at least one electrical signal (E) representative of the detected deformation and / or strain (S) based on the at least one photonic signal (L); A method comprising the step of determining the braking torque (BT) based on the at least one electrical signal (E) representing the deformation and / or strain (S). **Claim 2** The at least one washer device (D) includes a plurality of washer devices (D1, D2, D3, D4), The at least one fixed interface includes a plurality of fixed interfaces (i, ii, iii, iv), The at least one deformation and / or strain sensor (FBG) includes a plurality of deformation and / or strain sensors (FBG1, FBG2, FBG3, FBG4, FBG5, FBG6), The inserting step includes inserting each of the plurality of washer devices (D1, D2, D3, D4) into each of the plurality of fixed interfaces (i, ii, iii, iv), Each of the plurality of washer devices (D1, D2, D3, D4) incorporates the plurality of deformation and / or strain sensors (FBG1, FBG2, FBG3, FBG4, FBG5, FBG6), The determining step includes determining the braking torque (BT) based on a plurality of electrical signals (Ejk) derived from photonic signals (Ljk) representing the deformations and / or strains (Sij) detected by the plurality of deformation and / or strain sensors (FBG1, FBG2, FBG3, FBG4, FBG5, FBG6), the method according to claim 1. **Claim 3** The clamping element has a first fixing bolt (63) and a second fixing bolt (64), The plurality of fixed interfaces has a first fixed interface (i), a second fixed interface (ii), a third fixed interface (iii) and a fourth fixed interface (iv), The plurality of washer devices (D1, D2, D3, D4) has a first washer device (D1), a second washer device (D2), a third washer device (D4) and a fourth washer device (D4), Inserting the first washer device (D1) into the first fixed interface (i) between the head of the first fixing bolt (63) and the first part of the brake caliper support (61); Inserting the second washer device (D2) into the second fixed interface (ii) between the head of the second fixing bolt (64) and the second part of the brake caliper support (61); Inserting the third washer device (D3) into the third fixed interface (iii) between the third part of the brake caliper support (61) and the brake caliper body (60); The method according to claim 2, including inserting the fourth washer device (D4) into the fourth fixed interface (iv) between the fourth part of the brake caliper support (61) and the brake caliper body (60).

4. The plurality of fixed interfaces have a third fixed interface (iii) and a fourth fixed interface (iv); The plurality of washer devices (D1, D2, D3, D4) have a third washer device (D4) and a fourth washer device (D4); Inserting the third washer device (D3) into the third fixed interface (iii) between a part of the brake caliper support (61) and the brake caliper body (60); The method according to claim 2, including inserting the fourth washer device (D4) into the fourth fixed interface (iv) between another part of the brake caliper support (61) and the brake caliper body (60).

5. The optical fiber strain sensor is included in an optical fiber (14) arranged within a peripheral band (13) in the tangential direction of the at least one washer device (D); Each of the optical fiber strain sensors is obtained by each optical fiber part inclined with respect to the radial plane of the washer (p) at an acute or obtuse inclination angle different from each of the values of 0°, 90°, 180°, and 270°, and a strain (S) in a direction different from the normal direction and the tangential direction with respect to the washer is detected. The method according to any one of claims 1 to 4, wherein the detected strain (S) depends on both the normal component and the tangential component acting on the at least one deformation and / or strain sensor (FBG).

6. Incorporating at least one temperature sensor (5) of the fiber Bragg grating type into the at least one washer device (D); Detecting, by each of the at least one temperature sensor (5), a temperature value (T) at the position where the at least one temperature sensor (5) is incorporated, and generating at least one auxiliary photonic signal (Lt) representing the temperature value (T). receiving, by the optical reading / query unit (4) optically connected to the at least one temperature sensor (5), the at least one auxiliary photonic signal (Lt); generating, by the optical reading / query unit (4), at least one auxiliary electrical signal (Et) representing the temperature value (T) based on the at least one auxiliary photonic signal (Lt); the determining step includes processing the at least one electrical signal (E) and the at least one auxiliary electrical signal (Et) to obtain a measured value of the braking torque (BT) taking into account temperature compensation; The method according to any one of claims 1 to 5, wherein the at least one temperature sensor (5) includes a fiber Bragg grating made of the same optical fiber (14) as the optical fiber in which the at least one strain and / or stress sensor (FBG) is made.

7. The fiber optic strain sensor is connected to the optical reading / query unit (4) by a first connecting optical fiber (31); The optical reading / query unit (4) is configured to activate the fiber optic strain sensor by transmitting an activating light emission (OA) via the first connecting optical fiber (31); The photonic signal (L) includes an optical spectrum reflected by the fiber Bragg grating type fiber optic strain sensor; The method according to any one of claims 1 to 6, wherein the optical spectrum reaches the optical reading / query unit (4) via the first connecting optical fiber (31).

8. The at least one strain and / or stress sensor (FBG) is connected to the optical reading / query unit (4) by a first input connecting optical fiber (32) and a second output connecting optical fiber (33); The optical reading / query unit (4) is configured to activate the at least one strain and / or stress sensor (FBG) by transmitting an active light emission (OA) via the first input connecting optical fiber (32); The photonic signal (L) includes an optical spectrum transmitted by the fiber Bragg grating type fiber optic strain sensor; The optical spectrum reaches the optical reading / query unit (4) via the second output connection optical fiber (33), according to the method of any one of claims 1 to 6.

9. The at least one deformation and / or strain sensor (FBG) is made by a Bragg grating associated with a central operating wavelength, The step of generating the at least one photonic signal (L) includes generating a plurality of photonic signals (L1, L2, L3, L4, L5, L6), The step of receiving includes receiving, by the optical reading / query unit (4), a plurality of photonic signals (L1, L2, L3, L4, L5, L6), The step of generating the at least one electrical signal (E) by the optical reading / query unit (4) includes generating a plurality of electrical signals (E1, E2, E3, E4, E5, E6) based on the plurality of photonic signals (L1, L2, L3, L4, L5, L6), The step of processing includes processing the plurality of electrical signals (E1, E2, E3, E4, E5, E6) to obtain a measured value of the braking torque (BT), according to the method of claim 6.

10. The step of transmitting, by the optical reading / query unit (4), via the connection optical fiber (3), a plurality of activation optical emissions (OA1, OA2, OA3, OS4, OA5, OA6) respectively at different operating wavelengths (λ1, λ2, λ3, λ4, λ5, λ6) to a plurality of deformation and / or strain elements by wavelength division multiplexing (WDM) transmission technology; The step of receiving, via the connection optical fiber (3), a plurality of optical spectra reflected by the plurality of deformation and / or strain sensors (FBG1, FBG2, FBG3, FBG4, FBG5, FBG6) and distinguishing them by demultiplexing using the wavelength division multiplexing (WDM) transmission technology; The method of claim 9, wherein the plurality of optical reflection spectra correspond to each of the plurality of photonic signals (L1, L2, L3, L4, L5, L6).

11. Before the step of determining, The step of transmitting the at least one electrical signal (E) and / or the at least one auxiliary electrical signal (Et) to the control unit (20) is included, The step of determining is, A method according to any one of claims 1 to 10, comprising the step of calculating the braking torque (BT) by one or more algorithms executed by one or more software programs based on the at least one electrical signal (E), or based on the at least one electrical signal (E) and the at least one auxiliary electrical signal (Et), or based on the plurality of electrical signals (Ea, E1, E2, E3, E4, E5, E6; Eij) and the at least one auxiliary electrical signal (Et), by a processor of the control unit (20).

12. The calculating step includes calculating the braking torque (BT) according to a predefined non-linear relationship between the braking torque (BT) and the deformation and / or strain detected by the at least one deformation and / or strain sensor (FBG) at a location where the at least one deformation and / or strain sensor (FBG) is incorporated into the at least one washer device (D). The non-linear relationship is represented by a computerized model or look-up table stored so as to be accessible by the processor of the control unit (20). The non-linear relationship is determined by a test and / or characterization and / or calibration step that is performed after the at least one washer device (D) including the deformation and / or strain sensor (D) is arranged and fixed at each of the fixed interfaces between the brake caliper body and the brake caliper support. The method according to claim 11.

13. The at least one washer device (D) has four washer devices (D1, D2, D3, D4). For each of the four washer devices (D1, D2, D3, D4), defining four non-linear models (NM1, NM2, NM3, NM4) adapted to determine three vector components of three axial forces (F1, F2, F3, F4) acting on each of the four washer devices (D1, D2, D3, D4). The method according to claim 2, further comprising the step of calculating the braking torque (BT) based on the three axial forces determined by the four non-linear models.

14. The defining step includes defining a basic non-linear model by FEM simulation. The method includes a step of adjusting parameters of the basic non-linear model by an initial calibration phase based on measured values of the deformation and / or strain (Sij) detected by the respective optical fiber strain sensors of the four washer devices (D1, D2, D3, D4), and simultaneous measured values of physical quantities that generate the deformation and / or strain (Sij) under known experimental conditions. The method according to claim 13, wherein the physical quantity includes the brake torque (BT), a preload (V) due to the tension of a fixing screw during assembly, and / or a pressure (P) applied by the brake caliper.

15. The method according to any one of claims 1 to 14, wherein the step of determining includes obtaining a dynamic measured value of a real-time trend of the brake torque (BT) based on a time change of the detected deformation and / or strain.

16. A brake caliper (6) with a sensor for a vehicle brake system, wherein the brake caliper (6) includes a brake caliper body (60), a brake caliper support (61), a first fixing bolt (63) and a second fixing bolt (64), and at least one washer device (D) for detecting deformation and / or strain, wherein the at least one washer device (D) is fixed and pressed between the brake caliper body (60) and the brake caliper support (61) corresponding to at least one fixing interface (i, ii, iii, iv) between the brake caliper body (60) and the brake caliper support (61), wherein the brake caliper (6) is a fixed caliper or a floating caliper, wherein the brake caliper (6) also has a washer-shaped or disc-shaped device body (1) extending along a radial reference plane (p), wherein the device body (1) has a first flat surface (11) and a second flat surface (12) parallel to the reference plane (p), which are arranged in contact with the surface of the fixing means and / or the brake caliper support (61) and / or the brake caliper body (60), and is provided at the at least one fixing interface (i, ii, iii, iv) between the brake caliper body (60) and the brake caliper support (61), or between the brake caliper support (61) and the heads of the clamp elements (63, 64). The apparatus main body (1) has a tangential peripheral band and / or a recess (13) that extends along a part or the periphery of the apparatus main body (1) in the at least one washer device (D), The apparatus main body (1) deforms when a force is applied, The deformations and / or strains locally present in each part of the at least one washer device (D) represent the forces acting on the at least one washer device (D), The brake caliper (6) further includes, an optical fiber (14) disposed along the tangential peripheral band and / or recess (13) or on the tangential peripheral band and / or recess (13), The optical fiber (14) includes one or more deformation and / or strain sensors of the fiber Bragg grating (FBG) type, The one or more deformation and / or strain sensors of the fiber Bragg grating (FBG) type are configured to detect the deformation and / or strain (S) acting on each detection position and generate at least one photonic signal (L) representing the deformation and / or strain (S), The one or more deformation and / or strain sensors are provided in respective portions of the optical fiber inclined with respect to the radial plane (p) at acute or obtuse angles different from 0°, 90°, 180°, and 270°, and detect the deformation and / or strain (S) in a direction different from the normal direction, tangential direction, and radial direction with respect to the reference plane (p) of the at least one washer device (D), The detected deformation and / or strain (S) depends on both the vertical and tangential components of the force acting on the one or more deformation and / or strain sensors, and / or on the three spatial vectors of the force acting on the one or more deformation and / or strain sensors, The one or more deformation and / or strain sensors transmit the at least one photonic signal (L) generated by the one or more deformation and / or strain sensors and receive at least one activating optical radiation (OA) for the one or more deformation and / or strain sensors, the brake caliper (6).

17. An optical reading / query unit (4) connectable to a remote control unit (20) external to the brake caliper (6) is included, The optical reading / query unit (4) is optically connected to the first photonic connection means (3) in order to receive at least one photonic signal (L). The optical reading / query unit (4) is configured to generate at least one electrical signal (E) representing the detected deformation and / or strain (S) based on the at least one received photonic signal (L). The brake caliper (6) according to claim 16, wherein the at least one electrical signal (E) is adapted to be transmitted to the remote control unit (20).

18. A first washer device (D1) at a first fixed interface (i) between the head of the first fixing bolt (63) and the first part of the brake caliper support (61); A second washer device (D2) at a second fixed interface (i) between the head of the second fixing bolt (64) and the second part of the brake caliper support (61); A third washer device (D3) at a third fixed interface (iii) between the third part of the brake caliper support (61) and the brake caliper body (60); The brake caliper (6) according to claim 16 or 17, comprising a fourth washer device (D4) at a fourth fixed interface (iv) between the fourth part of the brake caliper support (61) and the brake caliper body (60).

19. A vehicle brake system comprising the brake caliper (6) according to any one of claims 16 to 18.

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