Non-contact determination of coating characteristics

Abstract

A system for non-contact determination of one or more characteristics of a layered coating is provided. The system includes a determination unit and a measurement unit including a coating scanner, a vibration probe, and an optical device. The coating scanner includes an intrusion-protected transmitter for emitting scanning radiation and an intrusion-protected receiver for sensing interaction radiation resulting from interaction of the scanning radiation with one or more coating layers. The vibration probe includes an intrusion-protected emitter for emitting the probe radiation and an intrusion-protected sensor for sensing reflected radiation resulting from reflection of the probe radiation on the coating to detect vibrations of the coating in response to the reflected radiation. The optical device directs the scanning radiation and / or the probe radiation toward a common radiation direction and directs the interaction radiation toward the intrusion-protected receiver and / or directs the reflected radiation toward the intrusion-protected sensor. The determination unit determines one or more characteristics of the coating in response to the interaction radiation sensed by the coating scanner and the vibrations detected by the vibration probe. Methods and computer programs executable by the system are also provided.

Description

[Technical field]

[0001] The present disclosure relates to a system for contactlessly determining one or more characteristics of a coating having various layers. The present disclosure further relates to a method executable in or by such a system, and to a computer program suitable for carrying out said method.

[0002] This application claims the benefit of European Patent Application No. 20382744, filed August 12, 2020. [Background technology]

[0003] Various methods and systems for contactlessly determining the characteristics of a coating having one or more layers are known in the state of the art. Typical coating characteristics extracted by said known methods and systems are the thickness of the coating or the thickness of each layer of the coating.

[0004] Some of the known methods and systems are not suitable for environments with disturbing elements, such as dust, water, paint particles or other external factors typically present in production lines, as the methods and systems are based on very sensitive components and therefore may produce distorted results due to disturbances caused by dust, water, paint particles or other disturbing factors.

[0005] Some other known methods and systems for non-contact determination of coating characteristics fail due to one or more vibrations. It is known that vibrations are very common and unavoidable in production lines. Therefore, the other methods and systems are not suitable for the above type of vibration-laden environment. Summary of the Invention

[0006] It is an object of the present disclosure to provide a novel method, system, and computer program product that aims to solve at least some of the problems mentioned above.

[0007] In one aspect, a system for non-contact determination of one or more characteristics of a coating having one or more layers is provided. The system comprises a plurality of units having a determination unit and a measurement unit. The measurement unit includes a coating scanner, a vibration seeker, and an optical device. The coating scanner includes an intrusion protected transmitter configured in use to emit scanning radiation, and an intrusion protected receiver configured in use to sense interaction radiation resulting from interaction of the scanning radiation with one or more layers of the coating. The vibration seeker includes an intrusion protected emitter configured in use to emit probing radiation, and an intrusion protected sensor configured in use to sense reflected radiation resulting from reflection of the probing radiation on the coating and to detect vibrations of the coating in response to the reflected radiation. The optical device is configured in use to direct the scanning radiation and / or the probing radiation towards a common radiation direction, and in use to direct the interaction radiation towards the intrusion protected receiver and / or the reflected radiation towards the intrusion protected sensor. The determination unit is configured to determine one or more characteristics of the coating in response to the interaction radiation sensed by the coating scanner and the vibrations detected by the vibration seeker.

[0008] The proposed system makes it possible to obtain very effective results in environments with vibrations and disturbing particles such as, for example, dust, water, paint particles, etc. A typical environment of this kind is, for example, a production line. The proposed system makes it possible for an intrusion protected coating scanner and an intrusion protected vibration seeker to coexist and cooperate in a more reliable manner in the same system compared to the systems of the prior art. The optical device makes it possible for the respective radiation emitted by the coating scanner and the vibration seeker to converge in the final path to impinge on substantially the same point or area of ​​the coating. Thus, a double effect is simultaneously obtained in the proposed system, i.e. a reliable vibration compensation is obtained, since the intrusion protected coating scanner and the intrusion protected vibration seeker coexist cooperatively in the same system and both radiations emitted by the coating scanner and the vibration seeker are directed to impinge on substantially the same point or area of ​​the coating. Such a coincidence of the impingement points or areas means that vibrations are detected at the same points where the coating is inspected and therefore one or more vibration compensations can be applied that are more reliable.

[0009] The ingress protection used in the system according to the present disclosure may meet corresponding standards including classifications and ratings of the degree of protection provided by mechanical casings and electrical enclosures against ingress, dust, accidental contact, and water. Examples of such standards include, for example, European standard EN 60529, IEC standard 60529, etc. This IEC standard 60529 is sometimes referred to as the IP Code (International Protection Code) and is published by the International Electrotechnical Commission (IEC).

[0010] According to some implementations, the optical device may include at least one mirror configured to reflect, in use, the scanning radiation and / or the interrogation radiation towards a common radiation direction, and at least one mirror configured to reflect, in use, the interaction radiation towards an intrusion protected receiver and / or the reflected radiation towards an intrusion protected sensor. Each of the mirrors may be movable such that its tilt can be adjusted to optimize the reflection of the scanning radiation and / or the interrogation radiation on the corresponding mirror, and the reflection of the interaction radiation and / or the reflected radiation on the corresponding mirror. The at least one mirror for reflecting the scanning radiation and / or the interrogation radiation and the at least one mirror for reflecting the interaction radiation and / or the reflected radiation may be the same at least one mirror in some configurations. In some examples, a single mirror may be sufficient to cause all reflections.

[0011] In some configurations, the optical device may include at least one lens configured to direct the scanning radiation and / or the probing radiation in a common radiation direction in use, and at least one lens configured to direct the interaction radiation toward the intrusion protected receiver and / or the reflected radiation toward the intrusion protected sensor in use. The at least one lens for directing the scanning radiation and / or the probing radiation and the at least one lens for directing the interaction radiation and / or the reflected radiation may be the same at least one lens in some configurations. In some examples, only a single lens may be sufficient to produce all the desired directing. The directing of the corresponding one or more radiations by the one or more lenses may be performed through suitable focusing functions, and / or suitable collimation functions, and / or transparency functions, and / or any other convenient optical functions of the one or more lenses.

[0012] In some examples, the plurality of units can include a positioning unit configured to, in use, move the measurement unit towards a target position relative to the coating to be inspected. The target position can be a position such that, in use, the common radial direction is substantially perpendicular to the coating. The target position can be a position such that, in use, an intrusion protected transmitter of the coating scanner and / or an intrusion protected emitter of the vibration seeker is spaced from the coating by a target distance.

[0013] The positioning unit may include a position detector configured to detect when the measurement unit has reached the target position. The position detector may for example be based on a set of triangulation sensors, which may or may not be assisted by a vibration seeker. Such a triangulation system may use information from the vibration seeker to detect when the measurement unit has reached the target position. In this way, the target position may be detected more reliably. The positioning unit may include an actuator configured to move the measurement unit towards the target position. The actuator may for example include a robot arm or the like.

[0014] In some configurations, the coating scanner may be a terahertz or THz scanner.

[0015] In a further aspect, a method is provided for contactlessly determining one or more characteristics of a coating having one or more layers. The method includes operating a coating scanner (of the measurement unit), operating a vibration probe (of the measurement unit), and operating a determination unit. The coating scanner is operative to cause an ingress protected transmitter of the coating scanner to emit scanning radiation and an ingress protected receiver of the coating scanner to sense interaction radiation resulting from an interaction of the scanning radiation with one or more layers of the coating. The vibration probe is operative to cause an ingress protected emitter of the vibration probe to emit probing radiation and an ingress protected sensor of the vibration probe to sense reflected radiation resulting from reflection of the probing radiation on the coating, to detect vibrations of the coating in response to the reflected radiation. An optical device (of the measurement unit) directs the scanning radiation and / or the probing radiation towards a common radiation direction and directs the interaction radiation towards the ingress protected receiver and / or the reflected radiation towards the ingress protected sensor. The determination unit is operative such that a determination of one or more characteristics of the coating is made in response to the interaction radiation sensed by the coating scanner and the vibrations detected by the vibration probe.

[0016] In some examples, operating the determining unit may include generating a simulated signal based on a physical model, and performing an optimization process to optimize one or more parameters of the physical model and modify the simulated signal until the simulated signal matches the interaction radiation sensed by the ingress protected receiver of the coating scanner. The optimization process may be based on at least one of the following techniques: discrete differential evolution, topographical global optimization, basin hopping, SHG (Second Harmonic Generation), or dual annealing. The optimization process may be an adaptive and iterative optimization process with a stopping criterion based on an error function. The optimization process is performed in the time domain and / or the frequency domain.

[0017] The simulated signal may be determined to match the sensed interaction radiation if the deviation between the simulated signal and the sensed interaction radiation is within a tolerance threshold.

[0018] The one or more characteristics of the coating can be determined in response to one or more optimized parameters of the physical model, where the optimized parameters characterize an interaction of the scanning radiation with one or more layers of the coating, since the simulated signal is matched to the sensed interaction radiation. In particular, the one or more characteristics of the coating can be determined in response to the one or more optimized parameters of the physical model and vibration compensation based on vibrations detected by the vibration seeker.

[0019] In some embodiments, the method may further comprise storing in a knowledge base the knowledge acquired during the execution of the method, said knowledge comprising one or more knowledge items, such as, for example, the optimized physical model, the optimized one or more parameters of the physical model, the evolution of the one or more parameters during the optimization process, the determined one or more characteristics of the coating, their correlations / relationships with one or more of the other knowledge items, etc.

[0020] The optimization process may include retrieving an optimized physical model from a knowledge base to be used as the physical model to generate the simulated signal.

[0021] Operating the coating scanner to sense the interaction radiation can include applying one or more filtering techniques to the sensed interaction radiation for noise reduction, such as, for example, a Recursive Least Squares filter, a Wiener-Kolmogorov filter, a Least Mean Square Error, a Kalman filter, a Bishrink filter, a theoretical noise-free representation of the sensed interaction radiation, a genetic algorithm combined with an adaptive threshold, a matched filter and a thresholding function in conjunction with transform techniques such as Fourier, wavelet and empirical mode decomposition (EMD), and the like.

[0022] The one or more coating characteristics determinable by the methods according to the present disclosure may include one or more of the following characteristics: number of layers, thickness per layer, intermixing level of a layer, refractive index per layer, electric parameters per layer, magnetic parameters per layer, electromagnetic parameters per layer, Fresnel coefficients, propagation constants, propagation angles, roughness.

[0023] In yet a further aspect, there is provided a computer program comprising program instructions for causing a computing system to execute a method for non-contact determining one or more characteristics of a coating as described elsewhere in this disclosure. The computer program may be embodied on a storage medium and / or carried on a carrier signal.

[0024] In yet a further aspect, a computing system for non-contact determining one or more characteristics of a coating is provided, the computing system comprising a memory and a processor and embodying instructions stored in the memory and executable by the processor, the instructions including one or more functions for performing a method for non-contact determining one or more characteristics of a coating, such as those described elsewhere in this disclosure. [Brief description of the drawings]

[0025] Non-limiting examples of the present disclosure are described below with reference to the accompanying drawings. [Figure 1] FIG. 1 is a block diagram that generally illustrates a system for non-contact determination of one or more characteristics of a coating, according to an embodiment. [Diagram 2] FIG. 2 is a block diagram that illustrates generally a system for non-contact determination of one or more characteristics of a coating according to a further embodiment. [Figure 3a] 1A-1D are block diagrams that generally illustrate different embodiments of a system for non-contact determination of one or more characteristics of a coating according to the present disclosure. [Figure 3b] 1A-1D are block diagrams that generally illustrate different embodiments of a system for non-contact determination of one or more characteristics of a coating according to the present disclosure. [Figure 4] 1 is a flow chart that generally illustrates a method for non-contact determination of one or more characteristics of a coating, according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] 1 is a block diagram that illustrates a schematic of a system for non-contact determination of one or more characteristics of a coating 100, according to an embodiment. The coating 100 may include multiple layers 102 having an outermost layer 101 and an innermost layer 116. As generally illustrated in this figure, such a system for non-contact determination of one or more characteristics of a layered coating 100 may include multiple units or modules having a determination unit or module (not shown) and a measurement unit or module 103 including a coating scanner module 104, a vibration seeker module 105, and an optical device module 106. The coating scanner 104 may include an intrusion protected transmitter 107 configured, in use, to emit scanning radiation 108, and an intrusion protected receiver 109 configured, in use, to sense interaction radiation 110 resulting from interaction of the scanning radiation 108 with one or more layers 102 of the coating 100. The vibration probe 105 may include an intrusion protected emitter 111 configured, in use, to transmit or emit probe radiation 112, and an intrusion protected sensor 113 configured, in use, to receive reflected radiation 114 caused by reflection of the probe radiation 112 on the coating 100, and to detect vibrations of the coating 100 in response to the reflected radiation 114.

[0027] According to Fig. 1, the scanning radiation 108 may be emitted substantially perpendicular to the coating 100, and the probing radiation 112 may be emitted with its longitudinal axis substantially perpendicular to the longitudinal axis of the scanning radiation 108. The interaction radiation 110 may follow an expected "reverse" path (from the coating 100 to the coating scanner 104) caused by the interaction of the scanning radiation 108 with the layer 102 of the coating 100. Similarly, the reflected radiation 114 may also follow an expected "reverse" path (from the coating 100 to the vibration probe 105) caused by the reflection of the probing radiation 112 on the coating 100. In alternative configurations, the arrangement of the coating scanner 104 and the arrangement of the vibration probe 105 may be interchangeable between each other, and the overall configuration may produce the same or similar effects as described with respect to Fig. 1.

[0028] In use, the optical device 106 may be configured to direct the scanning radiation 108 and / or the interrogation radiation 112 towards a common emission point / direction 115, the interaction radiation 110 towards the intrusion protected receiver 109 and / or the reflected radiation 114 towards the intrusion protected sensor 113. In particular, as generally shown in FIG. 1 , the optical device 106 may include a mirror 106c configured to reflect the interrogation radiation 112 (from the intrusion protected emitter 111) towards the common emission point / direction 115 and reflect the reflected radiation 114 (from the coating 100) towards the intrusion protected sensor 113. In an alternative embodiment, the interrogation radiation 112 may be emitted “directly” (i.e., without any redirection or reflection) perpendicularly towards the coating 100, and a corresponding mirror may reflect the scanning radiation 108 perpendicularly towards the coating 100 and the interaction radiation 110 towards the intrusion protected receiver 109.

[0029] According to the particular example of Fig. 1, the mirror 106c can change the direction of the interrogation radiation 112 and the reflected radiation 114 by substantially 90°, respectively. This is consistent with the fact that in said particular example, the scanning radiation 108 is emitted "directly", i.e. without any redirection / reflection, substantially perpendicularly towards the coating 100, and the interrogation radiation 112 is emitted substantially perpendicularly to the scanning radiation 108. The same or similar principles may be applicable to the interaction radiation 110 and the reflected radiation 114, but in the opposite direction to the scanning radiation 108 and the interrogation radiation 112, respectively.

[0030] The mirror 106c may be movable to adjust the tilt of the mirror 106c to optimize reflection of the scanning radiation 108 and / or probing radiation 112, and reflection of the interaction radiation 110 and / or reflected radiation 114.

[0031] 1, the optical device 106 may comprise a lens 106a having a side 118 facing the inside of a casing 117 of the measurement unit 103 and another side 119 facing the outside of the casing 117. This lens 106a may have, for example, a function to collimate and / or focus the scanning radiation 108 towards a common emission point / direction 115, and a similar function in the "reverse" direction to direct the interaction radiation 110 from the coating 100 towards an ingress protected receiver 109. The optical device 106 may further comprise optical hardware or adjuster 106b for appropriately adjusting the scanning radiation 108 before it reaches the lens 106a. Thus, the optical hardware 106b and the lens 106a may cooperate optically to optimize the convergence of the scanning radiation 108 towards the common emission point / direction 115. The optical hardware or adjuster 106b may be movable and adjustable to appropriately optimize the conditioning of the scanning radiation 108 before it reaches the lens 106a, and the conditioning of the interaction radiation 110 before it reaches the intrusion protected receiver 109.

[0032] 1 includes a main schematic (diagram) at the top and a schematic at the bottom, the latter corresponding to a more detailed view of a particular implementation and / or arrangement of the coating scanner 104. The schematic at the bottom shows the coating scanner 104 from a perspective 120 at the side of the coating scanner 104, clearly showing the intrusion protected receiver 109 and the intrusion protected transmitter 107. The intrusion protected receiver 109 may be positioned at a tilt or angle 122 relative to the common radiation direction / point 115. The intrusion protected transmitter 107 may be positioned at a tilt or angle 121 relative to the common radiation direction / point 115.

[0033] The bottom schema also broadly illustrates the influence of the lens 106a (i.e., collimation and / or focus properties or parameters) and emission angle 121 to converge the scanning radiation 108 towards a common emission point / direction 115. The bottom schema also broadly illustrates the influence of the lens 106a (i.e., collimation and / or focus properties or parameters) and reception angle 122 to effect the path of the interaction radiation 110 towards the intrusion protected receiver 109. The described arrangement of the intrusion protected transmitter 107 and the intrusion protected receiver 109, the influence of the lens 106a on the scanning radiation 108 and the interaction radiation 110, and the resulting tilts / angles 121, 122 allow to avoid any interference of the scanning radiation 108 and the interaction radiation 110 with the mirror 106c. Each ingress protected transmitter 107 may be configured to produce a particular angle of incidence and / or a particular polarization of scanning radiation 108, and its respective ingress protected receiver 109 may be positioned accordingly. These positioning, lens-related and angle-based principles described for the coating scanner 104 may be applied to the vibration searcher 105 with the same or similar effect.

[0034] The determination unit (not shown) may be configured to determine one or more characteristics of the coating 100 in response to (such as signals and / or data characterizing) the interaction radiation 110 sensed by the coating scanner 104 and (such as signals and / or data characterizing) the vibrations detected by the vibration probe 105. Thus, the determination unit may be connected to the coating scanner 104 and the vibration probe 105 such that the determination unit (not shown in this figure) can receive the interaction radiation 110 (from the coating scanner 104) and the signals and / or data characterizing the vibrations of the coating 100 (from the vibration probe 105). The determination unit (not shown) may be located remotely with respect to the measurement unit 103.

[0035] The coating scanner 104 may be a terahertz scanner or a THz scanner. The intrusion protected receiver 109 and the intrusion protected transmitter 107 may be based on antennas, such as, for example, one or more photoconductive LT-InGaAs antennas. The coating scanner 104 may include one or more light generators (not shown). The one or more light generators may be one or more laser generators. The coating scanner 104 may comprise one or more delay lines (not shown), including a movable delay line for the coating scanner 104 to operate in different scan windows, and / or a hardware adjustable delay line for the coating scanner 104 to operate in one scan window that is adjustable through the displacement of the delay line.

[0036] 2 is a block diagram that illustrates a schematic of a system for non-contact determination of one or more characteristics of a coating 200 according to a further example. The coating 200 may include multiple layers 202, including an outermost layer 201 and an innermost layer 216. Some components in the measurement unit 203 may be equivalent or similar to corresponding components in the measurement unit 103 of FIG. 1. For example, a coating scanner 204 having an ingress protected transmitter 207 and an ingress protected receiver 209 may be similar to the coating scanner 104 having an ingress protected transmitter 107 and an ingress protected receiver 109 of FIG. 1. Thus, details regarding the scanning radiation 208 and the interaction radiation 210 may be similar to those described with respect to the scanning radiation 108 and the interaction radiation 110 of FIG. 1. The determination unit or module (not shown) may also be similar to the determination unit described with respect to FIG. 1.

[0037] The difference with respect to FIG. 1 may be that in FIG. 2 the optical device 206 may not include the mirror 106c of FIG. 1. The optical device 206 may include a lens 206a similar to the lens 106a of FIG. 1 but with certain optical characteristics. The lens 206a may be positioned with respect to the casing 217 of the measurement unit 203 such that a side 218 of the lens 206a faces the inside of the casing 217 and another side 219 of the lens 206a faces the outside of the casing 217. The lens 206a may be transparent to the scanning and interaction radiation 208, 210 as well as the probing and reflected radiation 212, 214. The optical device 206 may also include an optical hardware or adjuster 206b similar to the optical hardware or adjuster 106b of FIG. 1, positioned at a position 220 between the coating scanner 204 and the vibration probe 205 and the lens 206a as in the configuration of FIG. 1. The vibration seeker 205 with intrusion protected emitter 211 and intrusion protected sensor 213 may be similar to the vibration seeker 105 with intrusion protected emitter 111 and intrusion protected sensor 113 of FIG. 1, but may be arranged differently compared to the configuration of FIG. 1. This different arrangement allows to avoid the need for mirror 106c of FIG. 1, since there is no need to redirect / reflect the probing radiation and the reflected radiation 212, 214. As shown in FIG. 2, the vibration seeker 205 may be arranged between the intrusion protected transmitter 207 and the intrusion protected receiver 209 of the coating scanner 204. The scanning radiation and the probing radiation 208, 212 may converge towards a common emission point / direction 215 in a similar manner as described with reference to FIG. 1, but no reflection of the probing radiation 212 is required. Similar considerations regarding the tilt or angle 121, 122 of FIG. 1 may be applicable to the tilt or angle 221, 222. In an alternative configuration, the arrangement of the coating scanner 204 and the arrangement of the vibration searcher 205 may be interchangeable between each other and the overall configuration can provide the same or similar effect as described with respect to FIG. 2.

[0038] 3a is a block diagram that generally illustrates a system for non-contact determination of one or more characteristics of a coating according to yet another example. As generally illustrated in this figure, the system for non-contact determination of one or more characteristics of a coating can be used to inspect a paint coating 302 on a vehicle, such as a car 301, either in-line or off-line with a corresponding production line. The system according to the present disclosure may be applicable to inspection of any layered coating on any product or object having a coating, either in-line or off-line.

[0039] The system for non-contact determination of one or more characteristics of a coating may comprise a positioning unit 300 configured to move a measurement unit 303a towards a target position relative to the coating 302. The measurement unit 303a may be equivalent or similar to any of the measurement units 103, 203 described herein. Accordingly, reference numerals from Figures 1 and 2 may be reused in the following description of Figure 3.

[0040] The target position of the measurement unit 303a may correspond to a position that makes the common emission point / direction 115,215 substantially perpendicular to the coating 302. Additionally or alternatively, the target position may correspond to a position where the intrusion protected transmitter 107,207 of the coating scanner 104,204 and / or the intrusion protected emitter 111,211 of the vibration seeker 105,205 are spaced from the coating 302 by a target distance 310. The coating scanner 104,204 and its components (such as the intrusion protected transmitter 107,207, the intrusion protected receiver 109,209, etc.), as well as the vibration seeker 105,205 and its components (such as the intrusion protected emitter 111,211, the intrusion protected sensor 113,213, etc.), as well as the optical device 106,206 may be adjustable to define different possible target distances 310.

[0041] The positioning unit 300 may include a position detector (not shown) for detecting when the measuring unit 303a reaches a target position. The position detector may for example be based on a set of triangulation sensors. The positioning unit 300 may include an actuator configured to move the measuring unit 303a towards the target position. The actuator may for example include a robot arm 304 which may have different articulation joints 305, 306 with corresponding degrees of freedom. The positioning unit 300 may include a collision detector configured to detect when, in use, the positioning unit 300 and / or the measuring unit 303a get too close to one or more external elements. The positioning unit 300 may further include a collision protector configured to protect, in use, the positioning unit 300 and / or the measuring unit 303a from damage due to collision with any one or more external elements.

[0042] As generally shown in Fig. 3a, a system according to the present disclosure may include a controller unit 309 configured to control all or some of the other units in the system. The control unit 309 may be located inside a (e.g., suitably protected) casing 308 that may further include a determination unit 311 or complementary components 303b of the measurement unit 303a, such as, for example, one or more light generators, one or more delay lines, etc. The control unit 309 may be configured, for example, to send control signals to the robot arm 304, the measurement units 303a, 303b, etc. to appropriately control each of the above units so that they work together in synchrony to ensure extraction of features from the coating 302.

[0043] The measurement unit components 303a may include some elements of the coating scanner 104, 204 and vibration seeker 105, 205, such as the ingress protected transmitter 107, 207, the ingress protected receiver 109, 209, the ingress protected emitter 111, 211, the ingress protected sensor 113, 213, etc. The measurement unit components 303b may include some other elements of the coating scanner 104, 204 and vibration seeker 105, 205, such as one or more light generators, one or more delay lines, etc. The measurement unit components 303a and 303b are connected to each other via wired connections 307 of different lengths. Some of such connections may be electrical, for example to transmit control signals, operating signals, data signals, power signals, etc., and some other connections may be for transmitting optical signals. Important properties of the optical signal can be preserved regardless of the distance cable 307 by techniques such as dispersion pre-compensation, dispersion compensated cable, Bragg dispersion compensation, or any other known technique that can adequately compensate for distance effects.

[0044] Fig. 3b is a block diagram that shows a schematic representation of a system for contactlessly determining one or more characteristics of a coating according to yet a further example. According to this figure, the system for contactlessly determining one or more characteristics of a coating may include different systems 300, 303a, for example according to Fig. 3a, connected via one or more connections 307 to a common hardware 303b, 309, 311, which may for example be housed in a casing 308. Thus, a single control unit 309, a single determination unit 311 and a single measurement unit part 303b may be shared by different systems 300, 303a according to a one-to-many approach (one common hardware 303b, 309, 311 is combined with multiple systems 300, 303a). The functionality of this one-to-many configuration may be similar to the one-to-one configuration described with respect to the other figures, but may have a common hardware 303b, 309, 311 dedicated simultaneously to several systems 300, 303a. In this manner, the coating 302 can be analyzed simultaneously at different points or areas of the coated product / object 301, thus providing more reliable, efficient and complete results.

[0045] Figure 4 is a flow chart that generally illustrates a method for non-contact determining one or more characteristics of a coating, according to an embodiment. As generally illustrated in the figure, the non-contact determination method may be initiated (e.g., at block 400) upon detection of a starting condition, such as, for example, a request to initiate the method or an invocation of the method from an operator interface, etc. Because the non-contact determination method according to Figure 4 can be performed by a system according to the previous figures, reference numbers from Figures 1, 2, and 3 may be reused in the following description of Figure 4.

[0046] The non-contact determination method may further include (e.g., in block 401) operating the coating scanner 104, 204 of block 401 (within the measurement unit 103, 203) to cause an ingress protected transmitter 107, 207 of the coating scanner 104, 204 to emit scanning radiation 108, 208 and an ingress protected receiver 109, 209 of the coating scanner 104, 204 to sense interaction radiation 110, 210 resulting from the interaction of the scanning radiation 108, 208 with one or more layers 102, 202 of the coating 100, 200. This function performed in block 401 may be performed by a coating scanner module, such as, for example, module 104, 204 described above with reference to Figures 1 and 2. Thus, the functional details and considerations described with respect to module 104, 204 above may be similarly applicable to method block 401.

[0047] The non-contact determination method may further include (e.g., in block 402) operating a vibration seeker 105, 205 (of the measurement unit 103, 203) to cause an intrusion protected emitter 111, 211 of the vibration seeker 105, 205 to emit a probing radiation 112, 212 and an intrusion protected sensor 113, 213 of the vibration seeker 105, 205 to sense a reflected radiation 114, 214 caused by reflection of the probing radiation 112, 212 on the coating 100, 200 and to detect vibrations of the coating 100, 200 in response to the reflected radiation 114, 214. This function performed in block 402 may be performed by a vibration seeker module, such as, for example, the module 105, 205 described above with reference to Figures 1 and 2. Thus, the functional details and considerations described with respect to the module 105, 205 above may be similarly applicable to method block 402.

[0048] As generally described with reference to Figures 1 and 2, the optical device 106, 206 (of the measurement unit 103, 203) can direct the scanning radiation 108, 208 and / or the searching radiation 112, 212 towards a common radiation point / direction 115, 215, and can direct the interaction radiation 110, 210 towards an intrusion protected receiver 109, 209 and / or the reflected radiation 114, 214 towards an intrusion protected sensor 113, 213.

[0049] The non-contact determination method may further include (e.g., in block 403) operating a determination unit 311 to determine one or more characteristics of the coating 100, 200 in response to the interaction radiation 110, 210 sensed by the coating scanner 104, 204 and the vibrations detected by the vibration seeker 105, 205. This functionality performed in block 403 may be performed, for example, by the determination unit or module 311 described above with reference to other figures. Thus, the functional details and considerations described with respect to the determination module 311 above may apply to method block 403 as well.

[0050] The non-contact determination method may also include retrieving data from a knowledge base 405 containing knowledge learned in previous runs, for example, to further enhance the feature determination performed in block 403. Similarly, output data or knowledge learned during a current run may be stored in the knowledge base 405 to further enhance the accumulated knowledge for future runs of the method. Knowledge stored or storable in the knowledge base may include, for example, optimization parameters, optimized models, tolerance thresholds, etc.

[0051] The non-contact determination method may end when an end condition is detected (eg, at block 404), such as, for example, when one or more characteristics of the coatings 100, 200 are determined.

[0052] The non-contact determination method may further include generating a simulated signal based on a physical model and performing an optimization process to optimize one or more parameters of the physical model and modify the simulated signal until the simulated signal matches the interaction radiation 110, 210 sensed by the ingress protected receiver 109, 209 of the coating scanner 104, 204. In some configurations, the above processing based on the simulated signal and the optimization process may be performed by a determination unit 311. Accordingly, there may be suitable connections between the determination unit 311 and the coating scanner 104, 204 and the vibration searcher 105, 205 for the determination unit 311 to receive corresponding data and / or signals from the coating scanner 104, 204 and the vibration searcher 105, 205.

[0053] The optimization process may be based on at least one of discrete differential evolution, topographic global optimization, basin hopping, SHG, or dual annealing, etc. Additionally or alternatively, the optimization process may be an adaptive and iterative optimization process with a stopping criterion based on an error function. Additionally or alternatively, the optimization process may be defined to be performed in the time domain and / or in the frequency domain. The simulated signal may be assumed to match the sensed interaction radiation 110, 210 if the deviation between the simulated signal and the sensed interaction radiation 110, 210 is within a tolerance threshold. This tolerance threshold may be defined according to previous experiments and / or according to knowledge accumulated during previous executions of the non-contact determination method.

[0054] Considering that the optimized parameters adapt the simulated signal to the sensed interaction radiation 110, 210 and thus characterize the interaction of the scanning radiation 108, 208 with one or more layers of the coating 100, 200, one or more characteristics of the coating 100, 200 can be determined in response to the one or more optimized parameters of the physical model. In particular, one or more characteristics of the coating 100, 200 can be determined in response to the one or more optimized parameters of the physical model and further in response to vibration compensation based on the vibrations detected by the vibration seeker 105, 205.

[0055] The non-contact determination method may further include storing knowledge from execution of the method in a knowledge base, which knowledge may include knowledge items such as, for example, the optimized physical model, and / or one or more optimized parameters of the physical model, and / or the evolution of the one or more parameters during the optimization process, and / or the determined one or more characteristics of the coating 100, 200, and / or correlations / relationships between the determined one or more characteristics and one or more of the other knowledge items.

[0056] The optimization process may include retrieving an optimized physical model from a knowledge base from a previous execution of the method, and using the retrieved optimized physical model as a physical model to generate a simulated signal in a current execution of the method.

[0057] The coating scanner 104, 204 may operate to detect the interaction radiation 110, 210 by applying one or more filtering techniques for noise reduction to the sensed interaction radiation 110, 210, such as, for example, a recursive least squares filter, and / or a Wiener-Kolmogorov filter, and / or a minimum mean square error, and / or a Kalman filter, and / or a Bishrink filter, and / or a theoretical noise-free representation of the sensed interaction radiation 110, 210, and / or a genetic algorithm combined with an adaptive threshold, and / or a matched filter and thresholding function in conjunction with transform techniques such as Fourier, wavelet and empirical mode decomposition (EMD).

[0058] One or more characteristics of the coating 100, 200 that may be determined by methods according to the present disclosure may include, for example, the number of layers, and / or the thickness per layer, and / or the layer intermixing level per layer, and / or the refractive index per layer, and / or the electrical parameters per layer, and / or the magnetic parameters per layer, and / or the electromagnetic parameters per layer, and / or the Fresnel coefficients, and / or the propagation constants, and / or the propagation angles, and / or the roughness, etc.

[0059] Thus, the method for non-contact determination of one or more characteristics of a coating according to the present disclosure may be qualified as an adaptive and / or self-learning method in the sense that it is continuously generating knowledge and learning from it. In particular, such a proposed method may be adaptive to production, and each time a new coating characteristic is extracted or determined, the method may for example learn about the physical model used and store this knowledge (for example in a knowledge base) so that said stored knowledge may be used in future executions of the method. The method according to the present disclosure is also adaptive with respect to the model parameters of the physical model, which means that for example the physical parameters such as the refraction and absorption indices may be fixed, variable or pre-determined in advance over the frequency bandwidth of the scanning radiation used to inspect the layer of the coating.

[0060] Measuring the innermost layer prior to determining one or more characteristics of the complete coating may or may not be necessary in the methods and systems according to the present disclosure. The innermost layers onto which the coating layer can be deposited are also diverse, such as ferrous and non-ferrous metals, fiber composites, polymeric materials (e.g., thermoplastics), and the like.

[0061] As used herein, the term "module" may be understood to refer to software, firmware, hardware, and / or various combinations thereof. It should be noted that the modules are exemplary. Modules may be combined, integrated, separated, and / or duplicated to accommodate various applications. Also, functions described herein as being performed by a particular module may be performed by one or more other modules and / or one or more other devices instead of, or in addition to, the functions performed by the particular described module.

[0062] The modules may be implemented across multiple devices, associated or linked to corresponding methods of contactlessly determining one or more characteristics of the coatings proposed herein and / or to other components that may be local or remote to each other. Furthermore, modules may be moved from one device and added to another device, and / or may be included in both devices and associated with corresponding methods of contactlessly determining one or more characteristics of the coatings proposed herein. Any software implementation may be tangibly embodied in one or more storage media, such as, for example, a memory device, a floppy disk, a compact disk (CD), a digital versatile disk (DVD), or other device capable of storing computer code.

[0063] The method for non-contact determination of one or more characteristics of a coating according to the present disclosure can be implemented by a computing means, an electronic means, or a combination thereof. The computing means may be a set of instructions (e.g., a computer program), and the method for non-contact determination of one or more characteristics of a coating may then comprise a memory and a processor, embodying said set of instructions stored in the memory and executable by the processor. These instructions may include one or more functions for performing a corresponding method for non-contact determination of one or more characteristics of a coating, such as, for example, those described with reference to other figures.

[0064] If the method for non-contact determination of one or more characteristics of a coating is performed exclusively by electronic means, the controller of the system may be, for example, a CPLD (Complex Programmable Logic Device), an FPGA (Field Programmable Gate Array) or an ASIC (Application-Specific Integrated Circuit).

[0065] If the method for non-contact determination of one or more characteristics of a coating is a combination of electronic means and computing means, the computing means may be a set of instructions (e.g., a computer program) and the electronic means may be any electronic circuitry capable of performing the corresponding steps of the method for non-contact determination of one or more characteristics of a coating proposed in this specification, such as those described with reference to the other figures.

[0066] One or more computer programs may be embodied on a storage medium (e.g., a CD-ROM, a DVD, a USB drive, a computer memory, or a read-only memory) or may be carried on a carrier signal (e.g., an electrical or optical carrier signal).

[0067] The one or more computer programs may be in the form of source code, object code, code intermediate source and object code such as partially compiled form, or any other form suitable for use in performing the method for non-contact determination of one or more characteristics of a coating according to the present disclosure. The carrier may be any entity or device capable of carrying one or more computer programs.

[0068] For example, the carrier may comprise a storage medium such as a ROM, such as a CD-ROM or a semiconductor ROM, or a magnetic recording medium, such as a hard disk. Further, the carrier may be a transmissible carrier, such as an electrical or optical signal, which may be conveyed via electrical or optical cable or by radio or other means.

[0069] When the one or more computer programs are embodied in a signal which may be conveyed directly by a cable or other device or means, the carrier may be constituted by such a cable or other device or means. Alternatively, the carrier may be an integrated circuit in which one or more computer programs are embedded, the integrated circuit being adapted for performing, or for use in the performance of, the method of non-contact determination of one or more characteristics of a coating as proposed herein.

[0070] Only some examples are disclosed herein, but other alternatives, modifications, uses and / or equivalents are possible. Moreover, all possible combinations of the described examples are covered. Thus, the scope of the disclosure should not be limited by the specific examples, but should be determined only by a fair reading of the appended claims.

Claims

1. 1. A system for non-contact determination of one or more characteristics of a coating having one or more layers, the system comprising a plurality of units having a determination unit and a measurement unit including an intrusion protected coating scanner, an intrusion protected vibration probe, and an optical device, the ingress protected coating scanner comprising: an ingress protected transmitter configured, in use, to emit scanning radiation; and an ingress protected receiver configured, in use, to sense interaction radiation resulting from interaction of the scanning radiation with one or more layers of the coating; the intrusion protected vibration probe comprises an intrusion protected emitter configured, in use, to emit probing radiation; and an intrusion protected sensor configured, in use, to sense reflected radiation caused by reflection of the probing radiation on the coating and to detect vibrations of the coating in response to the sensed reflected radiation; the optical arrangement comprises at least one mirror configured, in use, to reflect the scanning radiation towards a common radial direction with the probing radiation, and at least one mirror configured, in use, to reflect the interaction radiation towards the ingress protected receiver; or the optical arrangement comprising at least one mirror configured, in use, to reflect the interrogation radiation towards a common radial direction with the scanning radiation, and at least one mirror configured, in use, to reflect the reflected radiation towards the ingress protected sensor; the determining unit is configured to determine the one or more characteristics of the coating in response to the interaction radiation sensed by the intrusion protected coating scanner and the vibrations detected by the intrusion protected vibration seeker. system.

2. 2. The system of claim 1, wherein each of the mirrors is movable to adjust a tilt of the mirror to optimize reflection of the scanning radiation and / or the probing radiation and reflection of the interaction radiation and / or the reflected radiation.

3. 2. The system of claim 1, wherein the optical device comprises at least one lens configured, in use, to direct the scanning radiation and / or the probing radiation towards the common radiation direction, and at least one lens configured, in use, to direct the interaction radiation towards the intrusion protected receiver and / or the reflected radiation towards the intrusion protected sensor.

4. The system of claim 1 , wherein the plurality of units includes a positioning unit configured to move the measurement unit towards a target position relative to the coating.

5. The system of claim 4 , wherein the target position is such that, in use, the common radial direction is substantially perpendicular to the coating.

6. 6. A system as claimed in claim 4 or 5, wherein the target location is such that, in use, the intrusion protected transmitter of the intrusion protected coating scanner and / or the intrusion protected emitter of the intrusion protected vibration seeker are spaced from the coating by a target distance.

7. The system according to claim 4 , wherein the positioning unit comprises a position detector configured to detect when the measurement unit has reached the target position.

8. The system of claim 7 , wherein the position detector is based on a set of triangulation sensors with or without assistance provided by the vibration seeker.

9. The system of claim 4 , wherein the positioning unit comprises an actuator configured to move the measurement unit towards the target position.

10. The system of claim 9 , wherein the actuator comprises a robotic arm.

11. The system of claim 1 , wherein the intrusion protected coating scanner is a terahertz or THz scanner.

12. 1. A method for non-contact determination of one or more characteristics of a coating having one or more layers, the method comprising: operating an intrusion protected coating scanner of a measurement unit to cause an intrusion protected transmitter of the intrusion protected coating scanner to emit scanning radiation and an intrusion protected receiver of the intrusion protected coating scanner to sense interaction radiation resulting from an interaction of the scanning radiation with the one or more layers of the coating; operating an intrusion protected vibration probe of the measurement unit to cause an intrusion protected emitter of the intrusion protected vibration probe to emit probing radiation, and causing an intrusion protected sensor of the intrusion protected vibration probe to sense reflected radiation produced by reflection of the probing radiation on the coating, and to detect vibration of the coating in response to the sensed reflected radiation; operating a determination unit such that a determination of the one or more characteristics of the coating is made in response to the interaction radiation sensed by the intrusion protected coating scanner and the vibrations detected by the intrusion protected vibration seeker; Including, the scanning radiation is reflected by at least one mirror towards a common radial direction with the interrogation radiation, and the interaction radiation is reflected by at least one mirror towards the ingress protected receiver; or the interrogation radiation is reflected by at least one mirror towards a common radial direction with the scanning radiation, and the reflected radiation is reflected by at least one mirror towards the ingress protected sensor; each of said mirrors being included in an optical device of said measurement unit; method.

13. generating a simulated signal based on a physical model; performing an optimization process to optimize one or more parameters of the physical model to modify the simulated signal until the simulated signal matches the interaction radiation sensed by an ingress protected receiver of the ingress protected coating scanner; The method of claim 12 further comprising:

14. The method of claim 13, wherein the optimization process is based on at least one of the following techniques: discrete differential evolution, topographical global optimization, basin hopping, SHG, or dual annealing.

15. The method according to claim 13 or 14, wherein the optimization process is an adaptive iterative optimization process with a stopping criterion based on an error function with a tolerance threshold.

16. The method according to any one of claims 13 to 15, wherein the optimization process is performed in the time domain and / or in the frequency domain.

17. determining the one or more characteristics of the coating, 17. The method according to any one of claims 13 to 16, comprising determining the one or more characteristics of the coating in response to the optimized one or more parameters of the physical model, taking into account that the optimized parameters adapt the simulated signal to the sensed interaction radiation and therefore characterize the interaction of the scanning radiation with the one or more layers of the coating.

18. 20. The method of claim 17, wherein determining the one or more characteristics of the coating comprises determining the one or more characteristics of the coating in response to the optimized one or more parameters of the physical model and vibration compensation based on the vibrations detected by the intrusion protected vibration seeker.

19. 19. The method according to any one of claims 13 to 18, further comprising a step of storing knowledge derived from the step of executing the method in a knowledge base, said knowledge comprising at least one of the following knowledge items: an optimized physical model, one or more optimized parameters of the physical model, the evolution of said one or more parameters during the optimization process, one or more determined characteristics of the coating and their correlations / relationships with one or more other knowledge items, and the evolution of the tolerance threshold.

20. 20. The method of claim 19, wherein the optimization process includes retrieving an optimized physical model from the knowledge base to be used as the physical model to generate the simulated signal.

21. 21. A computer program comprising program instructions for causing a computing system to carry out the method of any one of claims 12 to 20 for non-contact determination of one or more characteristics of a coating.

22. 22. A computer program as claimed in claim 21 embodied on a storage medium.

23. 22. A computer program as claimed in claim 21, carried on a carrier signal.

24. 21. A computing system for non-contact determination of one or more characteristics of a coating, the computing system comprising a memory and a processor, the computing system embodying instructions stored in the memory and executable by the processor, the instructions including functionality to perform the method of any one of claims 12 to 20 for non-contact determination of one or more characteristics of a coating.

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