Non-contact detection of physical features of material

Abstract

There is provided a method of contactlessly detecting a physical feature of a material by means of a sensor head comprising a position sensor and a scanning sensor coupled to each other, the scanning sensor having a position requirement associated with a target reflection associated to each position sensor, and a locator therefor, the method includes performing a positioning loop to converge the scan sensor to a position requirement based on operating the position sensor, verifying whether the position requirement is satisfied or not, and in the event that the position requirement is not satisfied, performing an optimization loop until an interaction property result optimized corresponding to the satisfaction of the position requirement; and once the location requirement is met, operating a scanning sensor to irradiate the material and sense an interaction of the irradiation with the material, and detecting a physical feature from the sensed interaction. Systems and computer programs adapted to perform such methods are also provided.

Description

[0001] This application claims the benefit of European Patent Application EP 23 382 318.6, filed on 31 March 2023.

[0002] The present disclosure relates to a method of non-contact detection of physical features of a material and to a system and computer program adapted to perform such a method. BACKGROUND

[0003] Different methods and systems are known in the prior art for non-contact determination of physical features of a coated material. Typical features extracted by said known methods and systems can be the thickness of one or more layers in a layered coated material, electrical parameters (e.g. complex refractive index, electrical conductivity, electrical resistance, etc.) or any other physical feature that can be imparted to the material (e.g. hardness, adhesion, defects, voids, discontinuities, etc.).

[0004] Such prior art systems often require that the non-contact sensor is positioned at a predefined position relative to the material in order to operate correctly, i.e. to detect the physical features of the material with acceptable accuracy. In some cases, this positioning of the non-contact sensor is not accurate enough, which can result in poor or insufficient measurements in e.g. curved surfaces. In other cases, the positioning can be inefficient, e.g. because too much time is required to achieve an effective positioning of the non-contact sensor. Known systems for non-contact determination of physical features of a material can also be expensive and can not be sufficiently robust. It is therefore desirable to provide such a cheaper, more robust, less error-prone system.

[0005] Another drawback of prior art non-contact measurement systems is that, in e.g. manufacturing or assembly lines, different instances of the material to be inspected can arrive at the measurement or control stage under variable or different conditions in terms of positioning, from one instance of the material to another. For example, different instances of the same type of object can reflect the variability of the manufacturing process and of the transportation system. These varying conditions can require a certain adaptability of the non-contact measurement system, but this is difficult to achieve. As a result, when there are said types of variable conditions, the prior art non-contact systems tend to erroneously or inaccurately detect the physical features of the target material.

[0006] It is an object of the present disclosure to provide new methods, systems and computer programs aiming at improving the way physical features of a material are non-contact detected in the prior art. SUMMARY

[0007] In one aspect, there is provided a method of non-contact detection of a physical feature of a material by a sensor head and its positioner, the sensor head comprising at least three position sensors and a scanning sensor coupled to each other, the scanning sensor having a position requirement with respect to the material, the position requirement being associated to a target reflection of each of the position sensors. Such a method, also referred to herein as a detector method, comprises performing a positioning loop with positioning iterations to cause the scanning sensor to converge to a satisfaction of the position requirement, verifying a satisfaction or a non-satisfaction of the position requirement, and in case of non-satisfaction, performing an optimization loop with optimization iterations until an optimized interaction property result corresponding to a satisfaction of the position requirement. The detector method further comprises, once the position requirement is satisfied (or has been satisfied), operating the scanning sensor to illuminate the material and to first sense an interaction of the illumination with the material, and detecting the physical feature from the first sensed interaction.

[0008] Each of the positioning iterations comprises operating each of the position sensors to radiate the material and to first sense a reflection of the radiation with the material, and determining a consistency or an inconsistency between the first sensed reflection and the target reflection associated thereto, and in case of consistency, exiting the positioning loop; in case of inconsistency, operating the positioner to start a new iteration of the positioning loop with a repositioning of the sensor head, according to the determined inconsistency.

[0009] Each of the optimization iterations comprises operating the scanning sensor to illuminate the material and to second sense an interaction of the illumination with the material, obtaining an interaction property from the second sensed interaction, and determining whether the interaction property is optimized or not optimized, and if not optimized, operating the positioner to start a new iteration of the optimization loop with a repositioning of the sensor head, according to the interaction property; if optimized, exiting the optimization loop, operating each of the position sensors to radiate the material and to second sense a reflection of the radiation with the material, and updating the target reflection from the second sensed reflection.

[0010] The terms "first" and "second" are used herein to distinguish between a (first) sensing of an interaction (by the scanning sensor) to determine a physical feature and a (second) sensing of an interaction (by the scanning sensor) in the optimization loop, and also to distinguish between a (first) sensing of a reflection (by the position sensors) in the positioning loop and a (second) sensing of a reflection (by the position sensors) to update the target reflection after performing the optimization loop.

[0011] The proposed detector method is based on trying to position the scanning sensor using only the position sensor to meet its position requirements, and if (eventually) it is deemed that the position requirements cannot be accurately met with only the position sensor, then the scanning sensor is subsequently used to cooperate with the position sensor to refine its own positioning. Once the position requirements are met as a result of said cooperation, the position sensor is operated to obtain a sensed reflection under the condition that the position requirements (of the scanning sensor) are met, and said sensed reflection is used to update the target reflection to be considered in the next execution of the detector method. This function of updating the target reflection is referred to herein as an update function. If the position requirements are met with only the position sensor, then the update function can be executed (to maximize the accuracy of the target reflection) or can not be executed (because the sensed reflection and the target reflection have been determined to coincide with each other).

[0012] The update function can comprise designating the second sensed reflection as the (new) target reflection under the condition that the position requirements are met. Alternatively, the update function can comprise using not only the current second sensed reflection (under the condition that the position requirements are met), but also the first sensed reflection and / or the second sensed reflection from a previous execution of the method.

[0013] The detector method according to the present disclosure thus has various advantages compared to prior art systems having the same or similar purpose. The detector method dynamically calibrates in such a way that more accurate measurement results can be produced and / or poor measurement results can be avoided even in case of difficult measurement conditions (e.g. curved surfaces on the material to be inspected, the effective surface not coinciding with the real surface of the material, etc.). The concept of effective surface is explained elsewhere in this specification. The detector method can adapt to changing conditions, e.g. on a production line. The detector method is efficient because most of the positioning will be based on the position sensor only, and the scanning sensor will only intervene in its own positioning in case of unexpected conditions.

[0014] The positioning loop can be exited or terminated without meeting the position requirements if / when a maximum number of positioning iterations (i.e. iterations of the positioning loop) is reached, or alternatively a maximum iteration time (i.e. of the positioning loop) elapses. In other words, the positioning loop iteratively tries to effectively position the scanning sensor by operating only the position sensor but limiting the maximum number of iterations or the maximum iteration time. If the maximum number of iterations / time is reached, it is deemed that effective positioning based on the position sensor only is not possible, and thus the positioning loop ends.

[0015] The positioning loop can also exit or terminate because the first sensed reflections and the target reflections are consistent with each other, thus satisfying the position requirement. Such consistency can be defined in terms of, for example, an absolute or non-absolute equality between each of the first sensed reflections and its associated target reflection, depending on a distance function between each of the first sensed reflections and its associated target reflection, such as mean square error, etc. Non-absolute equality can refer to equality plus / minus some acceptable error or tolerance (threshold-based comparison).

[0016] The interaction property can be obtained from the second sensed interaction (performed by the scanning sensor) based on, for example, time-domain processing and / or frequency-domain processing of the second sensed interaction. Such interaction property can be or can include one or more time-domain and / or frequency-domain processing parameters of the second sensed interaction. The time-domain processing parameters of the second sensed interaction can include, for example, energy, intensity, peak position, correlation with a reference signal, etc. The frequency-domain processing parameters of the second sensed interaction can include, for example, amplitude, energy, bandwidth, SNR, dynamic range, water absorption frequency, correlation with a reference signal, etc.

[0017] The optimization loop can be based on or can be implemented as an optimization method aiming at finding a position of the sensor head that optimizes an objective function representing the evolution of the interaction property as a function of the (re)positioning of the sensor head. The optimization method can iteratively change the position of the sensor head so as to make the objective function representing the interaction property converge to its maximum value (or to the maximum value), or in other words, to the optimized interaction property. The optimization method can be based on, for example, trying all possible positions of the sensor head to select the position that maximizes the interaction property, or based on gradient computation starting from an initial value of the interaction property, or based on a genetic algorithm, or based on a least square method, etc. Optimization methods and how they are implemented (in many ways) are known in the art, and therefore no detailed information about them is disclosed herein.

[0018] The scanning sensor can be a terahertz-based scanning sensor, in which case the operation of the scanning sensor can include operating it to emit a terahertz-based illumination towards the material, and sensing a terahertz-based interaction of said terahertz-based illumination with the material first / second, thereby obtaining the first / second sensed terahertz-based interaction. Alternatives to terahertz technology in the detector method according to the present disclosure can be, for example, opto-thermal technology, ultrasound technology, etc.

[0019] The position sensors can be laser-based position sensors, in which case the operation of each of the position sensors can comprise operating each of them to emit laser-based radiation towards the material, and first / second sensing laser-based reflections of said laser-based radiation with the material, thereby obtaining first / second sensed laser-based reflections. An alternative to the laser technology in the detector method according to the present disclosure can be, for example, ultrasound technology.

[0020] The position requirements of the scanning sensor relative to the material can comprise, for example, a requirement predefined distance between the scanning sensor and a point or location of a target surface of the material at which (or at which point or location) the illumination from the scanning sensor is to interact with; and / or a requirement predefined angle of incidence or inclination of the illumination from the scanning sensor with said point or location of the target surface. The target surface (or surface to be illuminated) can be the effective surface of the material to be inspected. The effective surface of the material can coincide or not with the real surface of the material, and refers to a theoretical surface with respect to which the scanning sensor (i.e. the sensor head) is to be positioned according to its predefined position requirements.

[0021] For example, if the material to be inspected has a layered structure, and each layer has a varying or non-uniform thickness or composition, the effective surface to be considered can not coincide with the (real) surface of its outermost layer, or in other words, with the surface of the material that the scanning sensor is facing or will face or illuminate for operation.

[0022] The points (or locations or areas) at which the radiation from the position sensors is to be reflected with the material, and the points (or locations or areas) at which the illumination from the scanning sensor is to interact with the material in the case of meeting the position requirements, can together define an incident material surface. The target reflections can be predefined with respect to said incident material surface (for attempting to correctly position the sensor head by operating only the position sensors).

[0023] The target reflections can be predefined experimentally in a calibration step prior to the execution of the detector method according to the present disclosure, for example in a manufacturing or installation or production line (on a large scale). The calibration can be performed by, for example, executing the detector method with initial target reflections predefined arbitrarily or intentionally incorrectly, to cause the first execution of the method to define accurate target reflections based on the cooperation between the scanning sensor and the position sensors.

[0024] The position requirements of the scanning sensor with respect to the material can be (correctly) predefined in relation to each of the target reflections associated to each of the position sensors, so that the correspondence or correspondence between each of the first sensed reflections (by each of the position sensors) and its associated target reflection corresponds to the fulfillment of the position requirements. This correspondence between the position requirements of the scanning sensor and each of the target reflections (which can be predefined (for example, by experiment) in a preliminary calibration step) can allow very efficiently positioning the scanning sensor with respect to the material using only the position sensors. This is possible because the instance / object to be checked next should have more accurate target reflections in order to correctly position the scanning sensor. Of course, if different points or areas of the material are to be checked, each of said points can have its specific associated target reflections. As mentioned before, this calibration can be achieved by performing the detector method with arbitrary (or deliberately meaningless) target reflections to cause a self-calibration of the detector method itself.

[0025] In some examples, each of the first / second sensed interactions (by the scanning sensor) can be or can include a first / second sensed reflection-based interaction and / or a first / second sensed transmission-based interaction.

[0026] The material to be checked can have a layered structure comprising one or more layers, with an outermost layer and possibly one or more inner layers, and the physical feature to be detected can be a property of the layered structure. Examples of such properties of the layered structure can include the thickness of at least one of the layers in the layered structure, an electrical parameter (for example, complex refractive index, electrical conductivity, electrical resistance, etc.) or any other physical feature (or non-electrical property) imparted to the material, such as hardness, adhesion, formation of defects, formation of voids, formation of discontinuities, etc., or any combination thereof.

[0027] In a detector method configured to check a layered material, the position requirements of the scanning sensor can include a requirement predefined distance between the scanning sensor and the visible or real surface of the outer (or outermost) layer of the layered material and / or a requirement predefined illumination incidence angle or tilt angle with respect to the visible or real surface of the outer (or outermost) layer of the layered material. The visible or real or visually recognizable or to be irradiated or irradiable surface of the (outer) layer refers to the surface visible to the material, or the surface that the scanning and position sensors will face to operate, or the surface that will be irradiated by the position sensors and illuminated by the scanning sensor, or the surface in contact with the ambient air or space. In alternative implementations, the position requirements can include a requirement predefined illumination incidence angle or tilt angle with respect to the outer and inner layers as a whole of the layered material. The outer and inner layers as a whole refer to all the layers or some of them that will interact with the illumination from the scanning sensor, so the position requirements are defined considering the entire layered structure.

[0028] In examples, the material can be a layered material, and the effective surface of the material can correspond to the real or visible or visually recognizable or to-be-irradiated or irradiable surface of the outermost layer of the layered material.

[0029] Alternatively, the effective surface can not coincide with the real or visible or visually recognizable or to-be-irradiated or irradiable surface of the outermost layer, in which case the position requirements can be defined with respect to the outer and inner layers of the layered material as a whole. In the latter case, the effective surface can thus correspond to a theoretical surface that depends on the interactions with the several layers of the layered material that the illumination of the scanning sensor is to undergo.

[0030] The position requirements can define points or positions in / on such irradiable surface at which the radiation from the position sensors is to undergo reflection with the material; and / or the target reflections can be related to the distance between each of the position sensors and the point / position of such to-be-irradiated surface at which the radiation from the position sensor is to undergo reflection with the material.

[0031] In some examples, the position sensors and the scanning sensor can be coupled to each other by a coupling in such a way that, in use, the scanning sensor illuminates the material at an illumination position (or area or point), and the position sensors irradiate the material at respective radiation positions (or areas or points) around the illumination position or area or point. For example, the position sensors and the scanning sensor can be coupled to each other in such a way that the position sensors irradiate points / areas of the material forming a triangle (or other polygon), while the scanning sensor illuminates a central point / area in the triangle (or other polygon) on the material to be inspected. Such an arrangement or coupling between the position sensors and the scanning sensor allows them to be operated in a coordinated manner to efficiently and accurately position the scanning sensor in accordance with its position requirements.

[0032] In examples, a multi-object method of non-contact detection of physical features in a plurality of instances or objects of the material can be provided. Such a multi-object method or multi-object detector method can comprise performing any of the (single-object) detector methods disclosed herein for each of the instances or objects of the material to non-contact detect the physical features in each of the plurality of instances or objects of the material.

[0033] In another aspect, there is provided a system for non-contact detection of a physical feature of a material by a sensor head and its positioner, the sensor head comprising at least three position sensors and a scanning sensor coupled to each other, the scanning sensor having a position requirement with respect to the material, the position requirement being associated to a target reflection associated to each of the position sensors. Such a system (also referred to herein as a detector system) comprises the sensor head, the positioner of the sensor head, a scanning sensor operator, a position sensor operator, a positioner operator, a positioning circulator, an optimization circulator and a feature determiner. The detector system is configured to perform, by the positioning circulator, a positioning cycle with positioning iterations to cause the scanning sensor to converge to a satisfaction of the position requirement, verify the satisfaction or non-satisfaction of the position requirement, and in case of non-satisfaction, perform, by the optimization circulator, an optimization cycle with optimization iterations until an optimized interaction property result corresponding to the satisfaction of the position requirement; and once the position requirement is satisfied (or has been satisfied), operate, by the scanning sensor operator, the scanning sensor to irradiate the material and first sense an interaction of the irradiation with the material, and detect, by the feature determiner, the physical feature from the first sensed interaction.

[0034] Each of the positioning iterations (performed by the positioning circulator) comprises operating, by the position sensor operator, each of the position sensors to radiate the material and first sense a reflection of the radiation with the material, and determine a consistency or inconsistency between the first sensed reflection and the target reflection associated thereto, and in case of consistency, exit the positioning cycle; in case of inconsistency, operate, by the positioner operator, the positioner of the sensor head to start a new iteration of the positioning cycle in case of repositioning the sensor head.

[0035] Each of the optimization iterations (performed by an optimization loop) comprises illuminating the material by operating the scanning sensor by the scanning sensor operator and secondarily sensing the interaction of the illumination with the material, obtaining an interaction property from the secondarily sensed interaction, and determining whether the interaction property is optimized or not optimized, and if not optimized, operating the positioners of the sensor head by the positioner operator in accordance with the interaction property to start a new iteration of the optimization loop with repositioning the sensor head; if optimized, exiting the optimization loop, operating each of the position sensors by the position sensor operator to radiate the material and secondarily sensing the reflection of the radiation with the material, and assigning the secondarily sensed reflection as a target reflection; alternatively, re-computing a target reflection in accordance with the secondarily sensed reflection and historical first and / or secondarily sensed reflections from previous executions of the method.

[0036] As the detector system is adapted or configured to perform the detector method, the functions and advantageous aspects or principles commented for the detector method can be similarly ascribed to the detector system.

[0037] In yet another aspect, a computer program is provided comprising program instructions for causing a system or computing system to perform a method of non-contact detection of a physical feature of a material, such as the methods described in other parts of the present disclosure. These computer programs (also referred to herein as detector computer programs) can be embodied on a storage medium and / or carried on a carrier signal.

[0038] As the detector computer program is adapted or configured to perform the detector method, the functions and advantageous aspects or principles commented for the detector method can be similarly ascribed to the detector computer program.

[0039] In yet another aspect, a computing system for non-contact detection of a physical feature of a material is provided, the computing system (also referred to herein as a detector computing system) comprising a memory and a processor, which contain instructions stored in the memory and executable by the processor, and the instructions comprise functions to perform a method of non-contact detection of a physical feature of a material, such as the methods described in other parts of the present disclosure.

[0040] As the detector computing system is adapted or configured to perform the detector method, the functions and advantageous aspects or principles commented for the detector method can be similarly ascribed to the detector computing system. BRIEF DESCRIPTION OF DRAWINGS

[0041] Non-limiting examples of the present disclosure will be described below with reference to the accompanying drawings, in which:

[0042] Figure 1is a schematic illustration of a block diagram of a non-contact detector for non-contact detection of a physical feature of a material according to an example.

[0043] Figure 2 is a schematic illustration of a flow chart of a method of non-contact detection of a physical feature of a material according to an example.

[0044] Figure 3 is a schematic illustration of a flow chart of a method of non-contact detection of a physical feature of a material according to other examples.

[0045] Figures 4A-4E is a schematic illustration of a position requirement, an active surface and an incident material surface as referred to herein. DETAILED DESCRIPTION

[0046] Figure 1 is a schematic illustration of a block diagram of a non-contact detector 100 for non-contact detection of a physical feature of a material according to an example. As generally shown in the figure, the non-contact detector 100 can comprise the following modules or units: at least three position sensors (not shown) and associated position sensor operators 101, an optimization circulator 102, a positioning circulator 103, a scanning sensor (not shown) and a corresponding scanning sensor operator 104, a positioner of the sensor head (not shown) and an associated positioner operator 105, and a feature determiner 106. The position sensors and the scanning sensor are coupled to each other in a sensor head (not shown). The scanning sensor can have a position or position requirement with respect to the material, which position or position requirement is associated to a target reflection associated to each of the position sensors.

[0047] The scanning sensor can for example be a terahertz based scanning sensor, an opto-thermal based scanning sensor, an ultrasound based scanning sensor, etc. The position sensors can for example be laser based sensors, ultrasound based sensors, etc.

[0048] The position sensor operators 101 can be configured to perform a positioning function, including operating the at least three position sensors to cause each position sensor to emit an illumination (e.g. laser based illumination), and to sense a reflection of the (e.g. laser based) illumination by the material for each of the illuminations, thereby obtaining a sensed (e.g. laser based) reflection for each of the position sensors. The scanning sensor operator 104 can be configured to perform a scanning function, including operating the scanning sensor to cause it to emit radiation (e.g. terahertz based radiation) and to sense an interaction of the radiation with the material, thereby obtaining a sensed (e.g. terahertz based) interaction.

[0049] The aforementioned coupling between the position sensor and the scanning sensor can be implemented by the coupler such that, in use, the scanning sensor irradiates the material at the irradiated location or area or point and the position sensor radiates the material at the corresponding radiated location or area or point around the irradiated location or area or point.

[0050] The position requirement of the scanning sensor can be predefined in terms of a required distance and / or irradiation incidence angle (or tilt angle) with respect to the effective surface or with respect to a target area or point on the effective surface of the material to be inspected, for example. The so-called effective surface will be referred to with respect to Figures 4A to 4E will be described in detail. In an example, the position requirement of the scanning sensor can be predefined in terms of a required distance and / or irradiation incidence angle (or tilt angle) with respect to the outer layer of the material or with respect to the outer layer and the inner layer of the material.

[0051] The positioning circulator 103 can be configured to perform a positioning cycle (with iterations) to converge the scanning sensor to meet its position requirement. The positioning circulator 103 can exit the positioning cycle when an end cycle condition is met (whether or not the position requirement is met). Such an end cycle condition can include, for example, reaching a maximum number of iterations of the positioning cycle or a maximum iteration elapsed time. In other words, the positioning circulator 103 can iteratively attempt to position the sensor head, in particular the scanning sensor, to meet its position requirement with respect to the material to be inspected, but limited to a maximum number of iterations or a maximum iteration elapsed time.

[0052] The positioning circulator 103 can be configured to perform each iteration of the positioning cycle, including performing a positioning function by the position sensor operator 101 and determining a consistency (or correspondence) or inconsistency (or non-correspondence) between each sensed reflection (from the performance of the positioning function) and its associated target reflection. The consistency or correspondence between each sensed reflection and its associated target reflection can be referred to herein as a “favorable consistency”, which means that the position requirement of the sensor head is met, and thus it is well positioned with respect to the material. The inconsistency or non-correspondence between at least one sensed reflection and its associated target reflection can be referred to herein as an “unfavorable inconsistency”, which means that the position requirement of the sensor head is not met, and thus it is not well positioned with respect to the material. Other parts of the present disclosure explain how to determine the consistency or inconsistency between a sensed reflection and a target reflection, for example based on an absolute or non-absolute one-to-one equality.

[0053] When the positioning circulator 103 does not exit the positioning cycle but determines an unfavorable inconsistency (i.e. poor positioning of the sensor head), the positioners of the sensor head can be operated by the positioner operator 105 in accordance with the inconsistency determined in the current iteration in order to start a new iteration of the positioning cycle with a repositioning of the sensor head. If the positioning circulator 103 exits the positioning cycle due to an unfavorable inconsistency (i.e. poor positioning of the sensor head), it is considered that a correct sensor positioning by the positioning sensor has not been achieved, and therefore the control of the method can be transferred to the optimization circulator 102. If the positioning circulator 103 exits the positioning cycle with a favorable consistency (i.e. valid positioning of the sensor head), it is considered that a correct sensor positioning by the positioning sensor has been achieved, and therefore the control of the method can be transferred to the feature determiner 106.

[0054] The above determination whether the positioning cycle has terminated (by the positioning circulator 103) with or without meeting the position requirement can be referred to herein as a termination function.

[0055] The correlation between the position requirement and the target reflection can be such that a consistency or correspondence between each of the reflections sensed by each of the position sensors and its associated target reflection corresponds to a meeting of the position requirement.

[0056] The optimization circulator 102 can be configured to perform an optimization cycle (iteration) to optimize the interaction property, thereby obtaining an optimized interaction property corresponding to a meeting of the position requirement of the scanning sensor. The optimization cycle can be based on an iterative optimization method aiming at finding a position of the sensor head, the iterative optimization method optimizing an objective function representing an evolution of the interaction property as a function of the (re)positioning of the sensor head. Such optimization method can be based on any known optimization method, such as trying all possible positions of the sensor head to select the position maximizing the interaction property, gradient computation starting from an initial value of the interaction property, genetic algorithm, least square method, etc.

[0057] The optimization circulator 102 can be configured in such a way that each iteration of the optimization cycle comprises performing a scanning function by the scanning sensor operator 104, obtaining interaction properties from the interaction sensed at the performance of the scanning function, and determining whether the interaction properties are optimized or not. If it is determined that the interaction properties are not optimized, the positioner of the measurement head can be operated in accordance with the interaction properties obtained in the current iteration to start a new iteration of the optimization cycle with repositioning of the sensor head. If it is determined that the interaction properties are optimized, the optimization circulator 102 can exit the optimization cycle. After termination of the optimization cycle, a positioning function can be performed by the position sensor operator 101 and each of the reflections sensed at the performance of the positioning function can be used to specify a (new) target reflection to be considered at the next execution of the detector method. Such (new) target reflection can further be determined from the historically sensed reflections from previous executions of the method, as described elsewhere in this disclosure. This updating of the target reflection can be referred to herein as an updating function.

[0058] The updating function can be performed (to maximize the accuracy of the target reflection) or can not be performed (because the sensed reflections and the target reflection have been determined to coincide with each other) if the positional requirements are met using the position sensor alone.

[0059] The updating function can comprise specifying the reflection sensed in the case where the positional requirements are met as the (new) target reflection. Alternatively, the updating function can comprise using not only the currently sensed reflection (in the case where the positional requirements are met), but also the sensed reflections from previous executions of the method.

[0060] The interaction properties can be obtained from the interaction sensed at the performance of the scanning function in the same iteration of the optimization cycle, e.g. based on time domain processing and / or frequency domain processing of the sensed interaction. Such interaction properties can be or can comprise any of the time domain and / or frequency domain processing parameters of the sensed interaction referred to in other parts of this disclosure.

[0061] The feature determiner 106 can be configured to, upon determining the effective positioning of the scanning sensor, detect a feature of the material by performing a scanning function by the scanning sensor operator 104 and determine the feature of the material from the interaction sensed at the performance of the scanning function. The interaction can be a reflection-based and / or a transmission-based interaction.

[0062] The material to be inspected can be constructed as a layered material having one or several layers, and the physical feature to be detected can be the thickness of one or more layers in the layered structure, an electrical parameter (e.g., complex refractive index, electrical conductivity, and resistance) or other physical feature that can be imparted to the material, such as a defect, void, discontinuity, hardness, adhesion, etc.

[0063] Figure 2 is a flowchart schematically illustrating a method of non-contact detection of a physical feature of a material according to an example. As generally shown in the figure, when a start condition is detected (e.g., a user requests to start the detector method), the detector method can be initiated (e.g., at block 200). As described above according to Figure 2 the detector method of Figure 1 may be performed by the detector system of Figure 1 the reference numerals from Figure 2 may be reused in the following

[0064] The detector method can further include (e.g., at method block 201) performing a positioning loop in the same or similar manner as described with reference to Figure 1 The positioning functionality implemented or implementable at method block 201 can be performed by, for example, the positioning loop 103 in cooperation with the position sensor operator 101 and the positioner operator 105, as previously described with reference to Figure 1 Thus, the functional details and considerations explained with respect to the modules 101, 103, 105 can be similarly attributed or attributable to method block 201.

[0065] The detector method can further include (e.g., at method block 202) determining whether the positioning loop exited in satisfaction or non-satisfaction of the position requirement of the sensor head (e.g., at the previous block 201), and transitioning to method block 203 if N is not satisfied, or to method block 205 if Y is satisfied. The functionality implemented or implementable at method block 202 can be the same or similar to the termination functionality previously described with reference to Figure 1 Thus, the functional details and considerations explained with respect to the termination functionality can be similarly attributed or attributable to method block 202. Figure 1

[0066] The detector method can further include (e.g., at method block 203) performing an optimization loop in the same or similar manner as described with reference to Figure 1 The optimization functionality implemented or implementable at method block 203 can be performed by, for example, the optimization loop 102 in cooperation with the scanning sensor operator 104 and the positioner operator 105, as previously described with reference to Figure 1 Thus, the functional details and considerations explained with respect to the modules 102, 104, 105 can be similarly attributed or attributable to method block 203.​

[0067] The detector method can further comprise (e.g., at method block 204) operating the position sensor to sense reflections and assigning said sensed reflections as (new) target reflections. Such (new) target reflections can further be determined from historical sensed reflections from previous executions of the method, as explained elsewhere in this disclosure. This functionality implemented or implementable at method block 204 can be the same or similar to the update functionality described earlier with reference to Figure 1 The functionality details and considerations explained in relation to said update functionality can similarly be attributed or attributable to method block 204. Figure 1

[0068] The detector method can further comprise (e.g., at method block 205) operating the scanning sensor to obtain sensed interactions, and determining physical features from said sensed interactions in the same or similar manner as described earlier with reference to Figure 1 This determining functionality implemented or implementable at method block 205 can be performed by, for example, the feature determiner 106 described earlier with reference to Figure 1 The functionality details and considerations explained in relation to said module 106 can similarly be attributed or attributable to method block 205.

[0069] Once the physical features of the material have been determined, a transition from block 205 to end block 206 can be performed to terminate execution of the detector method.

[0070] Figure 3 is a schematic illustration of a flowchart of a method of non-contact detection of physical features of a material according to an example. As generally shown in the figure, the detector method can be initiated (e.g., at block 300) when a start condition is detected (e.g., a user requests to start the detector method). As the detector method according to Figure 3 may be performed by a detector system according to Figure 1 and can correspond to a particular implementation of the detector method according to Figure 2 , the reference numerals from said Figure 3 and Figure 1 and Figure 2 may be reused in the following description of

[0071] Figure 3 The method blocks 301-304 of can correspond to a particular implementation of the method blocks 201 of Figure 2 The blocks 301-304 can implement the execution of the positioning loop in the same or similar manner as described earlier with reference to the method blocks 201 of Figure 2 The method blocks 301-304 of can correspond to a particular implementation of the method blocks 201 of Figure 3 ​The positioning loop of the method 100 can comprise performing a positioning function to obtain sensed reflections for each of the positioning sensors (block 301) and comparing each of the sensed reflections with its associated target reflection to determine a consistency or inconsistency between the sensed reflection and the target reflection (block 302). According to Figure 3 The positioning loop of the method 100 can further comprise determining whether an end loop condition is met (block 304), if Y, the positioning loop can be exited to transition to block 305, otherwise if N, the sensor head positioner can be operated according to the determined inconsistency to start a new iteration of the positioning loop with a repositioning of the sensor head (block 303). Thus, the functional details and considerations of the method block 201 of the method 100 can be similarly attributed or attributable to the method blocks 301-304 of the method 100. Figure 2 Figure 3 The method blocks 301-304 of the method 100 can correspond to specific implementations of the method block 203 of the method 200. Said blocks 301-304 can implement the execution of the optimization loop in the same or similar manner as described with reference to the method block 203 of the method 200. According to The method blocks 301-304 of the method 100 can further comprise determining whether an end loop condition is met (block 304), if Y, the optimization loop can be exited to transition to block 305, otherwise if N, the sensor head positioner can be operated according to the determined inconsistency to start a new iteration of the optimization loop with a repositioning of the sensor head (block 303). Thus, the functional details and considerations of the method block 203 of the method 200 can be similarly attributed or attributable to the method blocks 301-304 of the method 100.

[0072] Figure 3 The method block 305 of the method 100 can correspond to specific implementations of the method block 202 of the method 200. Said block 305 can implement the verification of whether the position requirements are met (block 202 of the method 200) by determining whether an acceptable or favorable consistency between the sensed reflections and the target reflections has been reached (block 305 of the method 100), if Y, the detector method can transition to block 311, otherwise, if N, the detector method can transition to block 306. Thus, the functional details and considerations of the method block 202 of the method 200 can be similarly attributed or attributable to the method block 305 of the method 100. Figure 2 The method block 306-309 of the method 100 can correspond to specific implementations of the method block 203 of the method 200. Said blocks 306-309 can implement the execution of the optimization loop in the same or similar manner as described with reference to the method block 203 of the method 200. According to Figure 3 The method blocks 306-309 of the method 100 can further comprise determining whether an end loop condition is met (block 309), if Y, the optimization loop can be exited to transition to block 310, otherwise if N, the sensor head positioner can be operated according to the unoptimized interaction properties to start a new iteration of the optimization loop with a repositioning of the sensor head (block 308). Thus, the functional details and considerations of the method block 203 of the method 200 can be similarly attributed or attributable to the method blocks 306-309 of the method 100. Figure 2 Figure 2 The method block 306 of the method 100 can correspond to specific implementations of the method block 204 of the method 200. Said block 306 can implement the execution of the scanning function in the same or similar manner as described with reference to the method block 204 of the method 200. According to Figure 3 The method block 307 of the method 100 can correspond to specific implementations of the method block 205 of the method 200. Said block 307 can implement the obtaining of the interaction properties from the sensed interactions in the same or similar manner as described with reference to the method block 205 of the method 200. According to The method blocks 306-309 of the method 100 can further comprise determining whether an end loop condition is met (block 309), if Y, the optimization loop can be exited to transition to block 310, otherwise if N, the sensor head positioner can be operated according to the unoptimized interaction properties to start a new iteration of the optimization loop with a repositioning of the sensor head (block 308). Thus, the functional details and considerations of the method block 203 of the method 200 can be similarly attributed or attributable to the method blocks 306-309 of the method 100.

[0073] Figure 3 The method block 306 of the method 100 can correspond to specific implementations of the method block 204 of the method 200. Said block 306 can implement the execution of the scanning function in the same or similar manner as described with reference to the method block 204 of the method 200. According to Figure 2 The method block 307 of the method 100 can correspond to specific implementations of the method block 205 of the method 200. Said block 307 can implement the obtaining of the interaction properties from the sensed interactions in the same or similar manner as described with reference to the method block 205 of the method 200. According to Figure 2 The method block 308 of the method 100 can correspond to specific implementations of the method block 206 of the method 200. Said block 308 can implement the operation of the sensor head positioner according to the unoptimized interaction properties in the same or similar manner as described with reference to the method block 206 of the method 200. According to Figure 3 The method block 309 of the method 100 can correspond to specific implementations of the method block 207 of the method 200. Said block 309 can implement the determination of whether the interaction properties have been optimized in the same or similar manner as described with reference to the method block 207 of the method 200. According to Figure 3 The method blocks 306-309 of the method 100 can further comprise determining whether an end loop condition is met (block 309), if Y, the optimization loop can be exited to transition to block 310, otherwise if N, the sensor head positioner can be operated according to the unoptimized interaction properties to start a new iteration of the optimization loop with a repositioning of the sensor head (block 308). Thus, the functional details and considerations of the method block 203 of the method 200 can be similarly attributed or attributable to the method blocks 306-309 of the method 100. Figure 2 The method block 306 of the method 100 can correspond to specific implementations of the method block 204 of the method 200. Said block 306 can implement the execution of the scanning function in the same or similar manner as described with reference to the method block 204 of the method 200. According to Figure 3Method boxes 306-309.

[0074] Figure 3 Method box 310 can correspond to Figure 2 A specific implementation of method block 204. Block 310 can perform a positioning function to obtain sensed reflections and designate them as (new) target reflections, which corresponds to... Figure 2 The update functionality implemented in box 204. Such (new) target reflections can be further determined based on historical sensed reflections from previous executions of the method, as described in other parts of this disclosure. Therefore, relative to... Figure 2 The functional details and considerations of method block 204 can be similarly assigned or can be assigned. Figure 3 Method box 310.

[0075] Figure 3 Method box 311 can correspond to Figure 2 A specific implementation of method block 205. Block 311 can operate a scanning sensor to obtain sensed interactions and to reference... Figure 2 The same or similar method described in box 205 determines physical characteristics based on the sensed interactions. Therefore, relative to... Figure 2 The functional details and considerations of method block 205 can be similarly assigned or can be assigned. Figure 3 Method box 311.

[0076] Once the physical characteristics of the material are determined, a transition from box 311 to closing box 312 can be performed to terminate the execution of the detector method.

[0077] In such Figure 2 and Figure 3 In detector methods like these, target reflections are updated not only based on reflections sensed by the position sensor during the current execution of the method (in the optimization loop or immediately following, for example, in boxes 204 or 310), but also based on reflections sensed during previous executions of the method. This history-based approach can be more accurate in detecting physical features when positioning the scanning sensor. For example, such reflections sensed in boxes 204 or 310 of previous executions of the method (or after the position requirement Y is met at box 202, or after an acceptable consistency Y at box 305) are referred to herein as historically sensed reflections. If several points or areas of material are to be examined, each of these points or areas can have its own historically sensed reflections.

[0078] exist Figure 2 In the above-described history-based method, method block 204 can determine the (new) target reflection based on the currently sensed reflection and, in addition, on the historical sensed reflections accumulated along the previous execution of the method. Figure 3In a middle ground, a method block 310, adapted to the above history-based approach, can determine the (new) target reflection similarly from the currently sensed reflection and in addition from the history of sensed reflections accumulated along previous executions of the method.

[0079] In an example according to the so-called large-scale approach, a multi-object inspection method, system and computer program can be provided for non-contact detection of physical features of a material in a plurality of instances or objects of the material. Such a multi-object inspection method can be suitable for inspection of a manufacturing or production line of objects of the same type at a detection or control stage in the manufacturing line. A transport system (e.g. a conveyor belt) can be used to transport the objects and pass them one by one through the detection or control stage where a detector system configured to perform a detector method according to the present disclosure can be arranged. Each object to be inspected can have several points or areas to be inspected, in which case the detector system can be configured to move from one point / area to the next (of the same object) to perform the detector method at each point / area to be inspected.

[0080] The multi-object inspection method can comprise performing a detector method according to any one of the present disclosure for each object to be inspected. Such a detector method can be performed when each object to be inspected reaches the detection or control stage. Upon reaching, the detector method can be performed for each point / area to be inspected of the object to non-contact detect the physical features of the material in each point / area to be inspected of said object.

[0081] The detector method in the multi-object inspection method can recalibrate itself (by means of an optimization loop and accordingly updating the target reflection) according to different scenarios. For example, when a first object of a given type, model or specification is inspected upon first execution of the detector method, the target reflection is arbitrarily or intentionally wrongly predefined to cause the first execution of the detector method to define accurate specific target reflections for each point / area to be inspected on the object. Another scenario can be, for example, when certain specifications of the object type vary from one object to another, affecting the execution of the detector method in / at certain points / areas to be inspected.

[0082] Such a history-based approach can be useful for the multi-object inspection method, for example described in other parts of the present disclosure. According to such a history-based approach, artificial intelligence (Al) techniques can be used in the method to improve the updating of the target reflection and thus the positioning of the scanning sensor and the obtaining of the measurement results or feature detection. Depending on different parameters (e.g. their frequency), more or less weight can be given to the current and history sensed reflections, and thus the adaptation speed of the detector method can be advantageously adjusted.

[0083] The detector method, which can be referred to as a multi-object inspection method (explained in other parts of the present disclosure), can enable correct and / or accurate measurements under distorted conditions based on adapting the target reflection to production variations and inherent variability. The distorted conditions can include, for example, variations due to inherent variability of positioning of the entire object (e.g., at a transportation system such as a conveyor belt), inherent variability of the state of the part of the object to be inspected (e.g., open or closed state of a car door in a quality control stage of a car body production line), variability of the manufacturing process (e.g., uniformity or non-uniformity of paint amount / thickness), etc., variations in the surface on which the position sensor is to radiate on a particular object instance.

[0084] Such distorted conditions can result in a situation where the position requirements cannot be met using only the position sensor (positioning cycle). Therefore, the detector method can subsequently execute an optimization cycle to adjust or compensate for the distorted conditions, whereby the position requirements are met even under such distorted conditions. Historical data can be processed to determine whether the obtained position corresponds to an error situation or to a measurable situation, in which case feature detection is performed.

[0085] For example, if it is detected that the obtained position corresponds to an error situation, updating the target reflection can be avoided, for example due to poor positioning of the object / material to be inspected (e.g., on a transportation system such as a conveyor belt), an error or unexpected state of the object / material to be inspected (e.g., a car door unexpectedly opened too much), an object / material type traceability error (e.g., a discrepancy between the object / material type conveyed and expected or indicated to the detector system), etc. In the case of such an error situation, the obtained sensed reflection (from the historical sensed reflections) can be discarded, and / or an error warning can be issued and / or the execution of the detector method can be aborted so that feature detection is not performed.

[0086] If the obtained position corresponds to a measurable situation, feature detection can be performed, and the current sensed reflection can be used to update the target reflection, and in examples, to remain in the historical sensed reflections. Features determined in the execution of the detector method can also be kept as historical data in the same or similar manner as the historical sensed reflections. In such a history-based approach, different techniques (e.g., AI techniques) can be used to detect abnormal values or abnormal features determined by the detector method with respect to the historical values, and proceed accordingly by, for example, performing a corrective action. Such corrective actions can include, for example, repeating the positioning and measurement, enforcing the optimization cycle regardless of whether the positioning cycle has terminated with the position requirements being met, adjusting the weight of the data to be saved (e.g., sensed reflections, determined features, etc.) or the association to be maintained with particular measurement results determined, etc.

[0087] The manufacturing line can be, for example, a vehicle / automobile manufacturing or production line, the object to be inspected can be a vehicle or automobile, and the material to be inspected can be a paint coating on the vehicle or automobile. The paint coating can be, for example, a layered paint coating comprising several layers of paint coating. The feature to be detected can be, for example, a thickness of one or more of the layers of the layered paint coating, an electrical parameter (e.g. complex refractive index, electrical conductivity, electrical resistance, etc.) or any other physical feature (e.g. hardness, adhesion, defects, voids, discontinuities, etc.) that can be imparted to the layered coating.

[0088] Figures 4A to 4E is a schematic illustration of a position requirement, an effective surface and an incident material surface as referred to herein.

[0089] Figure 4A The scanning sensor 400 and the position sensors 401-403 are shown coupled together by a coupler (not shown for simplicity) in a detector system for detecting a physical feature of a material 412. The scanning sensor 400 is configured to irradiate the material 412 at an irradiation point 411 and to sense an interaction of said irradiation with the material 412. The irradiation emitted by the scanning sensor 400 and its interaction with the material 412 (received by the scanning sensor 400) are shown (with each other) collinearly and indicated with the same reference 407. In the particular example shown, a transmission-based interaction is shown, but it can also be reflection-based. In other examples, the irradiation emitted by the scanning sensor 400 and its interaction with the material 412 (received by the scanning sensor 400) can not be (with each other) collinearly, and thus can form an angle, depending on, for example, the hardware arrangement in the scanning sensor 400.

[0090] The position sensor 401 is configured to radiate the material 412 at a radiation point 408 and to sense a reflection thereof on the material 412. The radiation emitted by the position sensor 401 and its reflection on the material 412 (received by the position sensor 401) are indicated with the same reference 404. The position sensor 402 is configured to radiate the material 412 at a radiation point 409 and to sense a reflection thereof on the material 412. The radiation emitted by the position sensor 402 and its reflection on the material 412 (received by the position sensor 402) are indicated with the same reference 405. The position sensor 403 is configured to radiate the material 412 at a radiation point 410 and to sense a reflection thereof on the material 412. The radiation emitted by the position sensor 403 and its reflection on the material 412 (received by the position sensor 403) are indicated with the same reference 406. For each of the position sensors 401-403, the emitted radiation and the received reflection 404-406 are shown collinearly, but they can form an angle, depending on, for example, the hardware arrangement in the position sensors 401-403.

[0091] The radiation points 408-410 can form a triangle or similar polygon around the illumination point 411. In case of more than three position sensors, other polygons can be formed by the corresponding radiation points.

[0092] The position requirements of the scanning sensor 400 can comprise a required predefined distance between the scanning sensor 400 and the incidence point 411 and / or a required predefined angle or inclination of the illumination emitted by the scanning sensor 400 with respect to an effective surface around the incidence point 411. By effective surface it is meant a theoretical surface around the incidence point 411 according to which the scanning sensor 400 (i.e. the sensor head) will be positioned according to its position requirements. In the particular example shown, the required predefined angle or inclination is shown perpendicularly with respect to the effective surface.

[0093] Figure 4B and Figure 4C A cross-sectional view of the material 412 to be inspected is schematically represented. Figure 4B An example of coincidence between the real surface and the effective surface of the material 412 illuminated 407 by the scanning sensor 400 at the incidence point 411 is illustrated. The material is a layered material with several layers 412a-412c, each having a uniform thickness and composition, as shown in the cross-sectional view. The illumination 407 emitted by the scanning sensor 400 is shown perpendicular to the visible or real surface of the outermost layer 412a of the material 412, since the real surface and the effective surface of the material 412 are coincident. The position requirements therefore comprise a perpendicular incidence and a certain distance between the scanning sensor 400 and the material 412.

[0094] Figure 4C An example of non-coincidence between the real surface and the effective surface of the material 412 illuminated 407 by the scanning sensor 400 at the incidence point 411 is illustrated. The material is a layered material with several layers 412'-412''', the outermost layer 412' having a non-uniform thickness (as shown in the cross-sectional view), the inner layers 412'', 412''' having a uniform thickness. In the particular case shown, the inner layers 412'', 412''' have a more significant influence on the features to be detected, and therefore the position requirements comprise a perpendicular incidence to the inner layers 412'', 412''', which therefore implies a non-perpendicular incidence to the real or visible surface of the outermost layer 412'. That is, in this case the real surface and the effective surface are not coincident. Therefore, the execution of the optimization cycle will maximize / optimize the interaction properties so that the non-perpendicular incidence to the real or visible surface of the outermost layer 412' shown will be selected / defined as a position requirement or part thereof.

[0095] Figure 4EAnother example illustrates the non-coincidence between the true and effective surfaces of material 412 irradiated at incident point 411 by scanning sensor 400 at point 411. The material 412 is a layered material 412 having several layers 412x, 412y, 412z with different compositions. In the specific case illustrated, the outermost layer 412x exhibits a heterogeneous distribution of material, which may affect the features to be detected; therefore, the position requirement includes non-perpendicular incident light onto the visible or true surface of the outermost layer 412x. Thus, in this case, the true and effective surfaces do not coincide. Therefore, the execution of the optimization loop will maximize / optimize the interaction properties such that, due to the heterogeneous material distribution in layer 412x, the non-perpendicular incident light onto the true or visible surface of the outermost layer 412x, as shown, will be selected / defined as a position requirement or a portion thereof.

[0096] Figure 4D Examples of the same Figure 4A A similar scenario, but material 412 has a curved outermost layer or visible surface. Considering that... Figure 4A and Figure 4D In both cases, the effective surface coincides with the real surface, and ideally, the angle of incidence or tilt should be perpendicular to the surface. Figure 4D The fact that the actual surface around the incident point 411 is curved means that the scanning sensor 400 (and the position sensors 401-403, which are fixed relative to the scanning sensor 400) need to be aligned with... Figure 4A Compared to tilting, it meets the position requirements.

[0097] The sensor head that meets the position requirements (connecting the scanning sensor 400 and the position sensors 401-403) defines the position to be reached relative to the incident point 411, which is the radiation 404-406 emitted by the position sensors 401-403. The radiation 404-406 from the position sensors 401-403 is reflected by the material 412 at points 408-410, while the illumination 407 from the scanning sensor 400 interacts with the material 412 at point 411, provided that the position requirements are met. Points 408-410 and point 411 together define what is referred to herein as the incident material surface.

[0098] Figure 4A and Figure 4D Different incident material surfaces are shown. Figure 4A In the definition, the four incident points 408-411 on the surface of the incident material are in the same plane, while... Figure 4DThis is not the case for the position sensors 401-403. The distance between the position sensors 401-403 and their associated incidence points 408-410 determines the reflections sensed by the position sensors 401-403 and thus the target reflections to be considered. Therefore, the target reflections to be considered for attempting to correctly position the scanning sensor 400 by operating only the position sensors 401-403 can be (pre)defined in terms of the incidence material surface formed by the incidence points 408-411. Each pair of sensed reflections and their associated target reflections corresponds to a pair of values whose conformity with each other indicates that the position requirements are met, the pair of values relating to the measured distances between the corresponding position sensors and the expected incidence points on the incidence material surface.

[0099] The calibration step can be performed initially to obtain initial target reflections to be used in the first execution of the detector method, as explained in other parts of this description. Since Figure 4A and Figure 4D the incidence material surface 408-411 in the scenario related to the fulfillment of the position requirements is different, the target reflections will also be different.

[0100] In the first execution of the detector method, a positioning loop is executed to position the scanning sensor 400 so as to correctly illuminate the incidence point 411 in Figure 4A and Figure 4D respectively. The positioning loop attempts to fulfill the position requirements of the scanning sensor 400 using only the position sensors 401-403. In the first iteration of the positioning loop, it can only be ensured that the required distance between the scanning sensor 400 and the incidence point 411 is fulfilled, but the orientation of the scanning sensor 400 with respect to the material 412 can not be the one that fulfills the conformity or correspondence between the sensed reflections and the target reflections. Therefore, the positioning loop can attempt to reposition the sensor head by preserving the distance to the incidence point 411 and operating the positioners of the sensor head (e.g., by performing a rotation) to find a position that fulfills the conformity between the sensed reflections and the target reflections, or in other words, the required distance between each of the position sensors 401-403 and the corresponding incidence points 408-410.

[0101] A number of repositioning attempts (i.e., positioning loop iterations) can be performed until a maximum number of iterations is executed or a maximum iteration time elapses and the conformity between the sensed reflections and the target reflections has not been achieved. In this case, the detector method can transition to an optimization loop to correctly position the scanning sensor 400 and determine new target reflections (associated with the position sensors 401-403) based on operating the scanning sensor 400 itself.

[0102] It turns out that the detector method is able to effectively position the scanning sensor 400 accurately by using only the position sensors 401-403 (positioning cycle) and / or the scanning sensor 400 itself (optimization cycle), while taking into account that it is difficult to realize a positioning of the scanning sensor 400 on material surfaces that are, for example, curved.

[0103] When no agreement between the sensed reflections and the target reflections is reached, and thus the scanning sensor 400 is considered not to be positionable based on the position sensors 401-403 alone, the optimization cycle can be executed to position the scanning sensor 400 based on itself. This was previously explained in the context of Figure 4A the scenario according to Figure 4D When the detector method is executed in the context of the scenario according to

[0104] Another twist can be that the point of incidence 411 is displaced from one object under inspection to the next object under inspection. This twist can be caused by, for example, a wrong stop of the object under inspection at the control or measurement stage. This displacement can be exacerbated by the transition from a flat surface to a curved surface, taking into account the scenarios according to Figure 4A and Figure 4D In these cases, the positioning cycle can have terminated without meeting the position requirements of the scanning sensor 400. Again, the optimization cycle can be executed to position the scanning sensor 400 accurately, in turn adjusting the target reflections according to the new scenario, so that the detector method recalibrates itself, as explained elsewhere in this description.

[0105] The above-described situations, i.e. the error situation and the measurable situation, can be better handled with the support of historical data (historical characteristics, historical sensed reflections, etc.) to take into account more data and thus obtain more accurate new results, as explained elsewhere in this disclosure.

[0106] The position sensors 401-403 and the scanning sensor 400 can be coupled to each other by a coupling (not shown) such that, in use, the scanning sensor 400 irradiates the material 412 at the irradiation point 411 and the position sensors 401-403 irradiate the material 412 at the respective radiation points 408-410 around the irradiation point 411. For example, the position sensors 401-403 and the scanning sensor 400 can be coupled to each other in such a way that the position sensors 401-403 irradiate points 408-410 of the material 12 forming a triangle (or another polygon) and the scanning sensor 400 irradiates the central point 411 in the triangle (or other polygon) on the material 12 to be inspected. This relative arrangement or coupling between the position sensors 401-403 and the scanning sensor 400 allows them to be operated in a coordinated manner, efficiently and accurately positioning the scanning sensor 400 according to its position requirements, even in complex scenarios such as the one described with reference to ​ and ​

[0107] It is desirable that the distance between the sensor head (i.e. the scanning sensor 400 and the position sensors 401-403) and the material 412 is close enough to ensure that the intensity of the radiation from the position sensors 401-403 and the irradiation from the scanning sensor 400 is sufficient to perform accurately, as the intensity of the radiation / irradiation decreases with distance. In turn, it is required that the sensor head is positioned not too close to the material 412 in order to minimize the risk of collision with it, for example when operating / rotating the positioner to (re)position the sensor head. This distance included in the position requirements of the scanning sensor 400 can be accurately predefined by experiment and / or theory.

[0108] Similarly, it is also recommended that the incidence points 408-411 maintain a sufficient distance from each other, otherwise the information they provide can not be of sufficient value to accurately position the sensor head. Having the incidence points 408-411 very close to each other (e.g. converging to a single incidence point) can minimize measurement defects due to the curvature of the surface, but in turn they can form a too small area, thus providing useless positioning information. Any type of measurement usually has an inherent error or background noise, so if the incidence points 408-411 are too close to each other, the information provided by each point can be more similar with respect to the noise or error level. Thus, the less effective information reduces the accuracy of the positioning (e.g. triangulation) method.

[0109] ​Conversely, the distance between the incident points 408-411 should not be too far from each other, as they together define the minimum area over which the sensor head is to be positioned. For example, when the material is to be inspected on a small area surface (e.g. an edge), the available material surface can be very limited. Therefore, the corresponding technical specifications can be predefined according to the target application, to adapt the incident points 408-411 to any potential material surface. Such specifications for ensuring the most suitable distribution of the incident points 408-411 can be predefined experimentally and / or theoretically.

[0110] Alternatively, the position sensors 401-403 and the scanning sensor 400 can be coupled to each other by a coupler (not shown) such that the radiation points 408-410 are not around the illumination point 411, but the illumination point 411 falls outside or separate from the polygon formed by the radiation points 408-410. However, such an arrangement can be less efficient as it can require multiple (re)positioning of the coupler (i.e. the sensor head) over (or directed to) the point or location of the target surface of the material. In the best case scenario, where no optimization loop needs to be performed, the coupler is first positioned to perform the positioning loop (ensuring the position requirements based on the position sensors are met), and then (re)positioned to operate the scanning sensor to illuminate the material and sense its interaction. In addition to the low time efficiency, the sensor head is also typically less compact, and therefore, to minimize the risk of collision, the distance between the sensor head (i.e. the scanning sensor 400 and the position sensors 401-403) and the material can need to be increased, resulting or exacerbating the aforementioned negative effects.

[0111] As used herein, the term "module" or "unit" can be understood to refer to software, firmware, hardware, and / or various combinations thereof. Notably, these modules are exemplary. These modules can be combined, integrated, separated, and / or duplicated to support various applications. Also, the functions described herein as being performed by a particular module can be performed by one or more other modules and / or one or more other devices, instead of or in addition to the function performed by the particular module.

[0112] These modules can be implemented across multiple devices, associated or linked to corresponding non-contact detectors for non-contact detection of the physical features of the materials presented herein, and / or linked to other components that can be located locally or remotely from each other. Also, the modules can be moved from one device and added to another device, and / or can be contained in both devices, associated to corresponding non-contact detectors presented herein. Any software implementation can be tangibly embodied, for example, in a memory device, a floppy diskette, a Compact Disc (CD), a Digital Versatile Disc (DVD), or other device(s) capable of storing computer code.

[0113] The non-contact detector for non-contact detection of a physical feature of a material according to the present disclosure can be implemented by a computing device, an electronic device or a combination thereof. The computing device can be a set of instructions (e.g. a computer program) and the non-contact detector can comprise a memory and a processor which specifically implement said set of instructions stored in the memory and executable by the processor. These instructions can comprise functions to perform a corresponding method of non-contact detection of a physical feature of a material, such as the methods described with reference to some of the figures.

[0114] If the non-contact detector for non-contact detection of a physical feature of a material is implemented only by an electronic device, the controller of the system can be for example a CPLD (Complex Programmable Logic Device), an FPGA (Field-Programmable Gate Array) or an ASIC (Application-Specific Integrated Circuit).

[0115] If the non-contact detector is a combination of an electronic device and a computing device, the computing device can be a set of instructions (e.g. a computer program) and the electronic device can be any electronic circuit capable of implementing the corresponding steps of the detector methods (non-contact detection of a physical feature of a material) presented herein, such as the methods described with reference to other figures.

[0116] The computer program can 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 carried on a carrier signal (e.g. on an electrical or optical carrier signal).

[0117] The computer program can be in the form of source code, object code, intermediate source and object code such as a partially compiled form (e.g. in a form that is translatable to an executable form by an interpreter) or in any other form suitable to implement the non-contact methods according to the present disclosure. The carrier can be any entity or device that can carry the computer program.

[0118] For example, the carrier can comprise a storage medium such as a ROM, for example a CD ROM or a semiconductor ROM, or a magnetic recording medium, for example a hard disk. Further, the carrier can be a transmissible carrier such as an electrical or optical signal, which can be conveyed via electrical or optical cable or by radio or other means.

[0119] When the computer program is embodied in a signal that can be conveyed directly by cable or other device or means, the carrier can be constituted by such cable or other device or means. Alternatively, the carrier can be an integrated circuit in which the computer program is embedded, the integrated circuit being suitable for executing or for use in executing the detector methods presented herein.

[0120] Although only a few examples have been disclosed herein, other alternatives, modifications, uses and / or equivalents thereof will become apparent to those skilled in the art from the foregoing disclosure. Additionally, the described examples are to be considered in a sense illustrative, and therefore the scope of the present disclosure should not be limited to the specific examples disclosed.

Claims

1. A method of non-contact detection of a physical feature of a material by a sensor head and a positioner thereof, the sensor head comprising at least three position sensors and a scanning sensor coupled to each other, the scanning sensor having a position requirement with respect to the material, the position requirement being related to a target reflection associated to each of the position sensors, the method comprising the steps of: performing a positioning loop with positioning iterations to make the scanning sensor converge to a satisfaction of the position requirement, verifying the satisfaction or non-satisfaction of the position requirement, and in case of non-satisfaction, performing an optimization loop with optimization iterations until an interaction property result optimized in correspondence with the satisfaction of the position requirement; and once the position requirement is satisfied, operating the scanning sensor to irradiate the material and to first sense an interaction of the irradiation with the material, and detecting the physical feature from the first sensed interaction; wherein, each of the positioning iterations comprises operating each of the position sensors to radiate the material and to first sense a reflection of the radiation with the material, and determining a consistency or inconsistency between the first sensed reflection and a target reflection associated thereto, and in case of consistency, exiting the positioning loop; in case of inconsistency, operating the positioner to start a new iteration of the positioning loop with repositioning of the sensor head according to the determined inconsistency; and wherein, each of the optimization iterations comprises operating the scanning sensor to irradiate the material and to second sense an interaction of the irradiation with the material, obtaining an interaction property from the second sensed interaction, and determining whether the interaction property is optimized or not, and if not, operating the positioner to start a new iteration of the optimization loop with repositioning of the sensor head according to the interaction property; if yes, exiting the optimization loop, operating each of the position sensors to radiate the material and to second sense a reflection of the radiation with the material, and updating the target reflection from the second sensed reflection.

2. The method of non-contact detection of a physical characteristic of a material of claim 1, wherein, The step of updating the target reflection from the second sensed reflection comprises assigning the second sensed reflection as the target reflection.

3. The method of non-contact detection of a physical characteristic of a material according to either of claims 1 or 2, wherein, The step of updating the target reflection from the second sensed reflection comprises updating the target reflection further from a first sensed reflection and / or a second sensed reflection from a previous execution of the method.

4. The method of non-contact detection of a physical characteristic of a material according to any one of claims 1 to 3, wherein, The position requirement of the scanning sensor is predefined based on a required predefined distance between the scanning sensor and a point or position of a target surface of the material to be interacted with irradiation from the scanning sensor, and / or based on a required predefined angle of incidence or inclination of irradiation from the scanning sensor with the point or position of the target surface.

5. The method of non-contact detection of a physical characteristic of a material of claim 4, wherein, The target surface of the material is an effective surface of the material.

2. A method of non-contact detection of a physical feature of a material by a sensor head and a positioner thereof, the sensor head comprising at least three position sensors and a scanning sensor coupled to each other, the scanning sensor having a position requirement with respect to the material, the position requirement being related to a target reflection associated to each of the position sensors, the method comprising the steps of: performing a positioning loop with positioning iterations to make the scanning sensor converge to a satisfaction of the position requirement, verifying the satisfaction or non-satisfaction of the position requirement, and in case of non-satisfaction, performing an optimization loop with optimization iterations until an interaction property result optimized in correspondence with the satisfaction of the position requirement; and once the position requirement is satisfied, operating the scanning sensor to irradiate the material and to first sense an interaction of the irradiation with the material, and detecting the physical feature from the first sensed interaction; wherein, each of the positioning iterations comprises operating each of the position sensors to radiate the material and to first sense a reflection of the radiation with the material, and determining a consistency or inconsistency between the first sensed reflection and a target reflection associated thereto, and in case of consistency, exiting the positioning loop; in case of inconsistency, operating the positioner to start a new iteration of the positioning loop with repositioning of the sensor head according to the determined inconsistency; and wherein, each of the optimization iterations comprises operating the scanning sensor to irradiate the material and to second sense an interaction of the irradiation with the material, obtaining an interaction property from the second sensed interaction, and determining whether the interaction property is optimized or not, and if not, operating the positioner to start a new iteration of the optimization loop with repositioning of the sensor head according to the interaction property; if yes, exiting the optimization loop, operating each of the position sensors to radiate the material and to second sense a reflection of the radiation with the material, and updating the target reflection from the second sensed reflection. The step of updating the target reflection from the second sensed reflection comprises assigning the second sensed reflection as the target reflection. The step of updating the target reflection from the second sensed reflection comprises updating the target reflection further from a first sensed reflection and / or a second sensed reflection from a previous execution of the method. The position requirement of the scanning sensor is predefined based on a required predefined distance between the scanning sensor and a point or position of a target surface of the material to be interacted with irradiation from the scanning sensor, and / or based on a required predefined angle of incidence or inclination of irradiation from the scanning sensor with the point or position of the target surface. The target surface of the material is an effective surface of the material.

6. The method of non-contact detection of a physical characteristic of a material of claim 5, wherein, The material is a layered material, and the effective surface of the material corresponds to a visually recognizable surface of an outermost layer of the layered material.

7. The method of non-contact detection of a physical characteristic of a material of claim 5, wherein, The material is a layered material, and the effective surface of the material corresponds to a theoretical surface that depends on interactions with several layers of the layered material that the illumination from the scanning sensor is to undergo.

8. The method of non-contact detection of a physical characteristic of a material according to any one of claims 1 to 7, wherein, The material is a layered material having an outermost layer with a visually recognizable surface or a surface to be radiated or a radiatable surface, and the position requirement defines a point or a location of the radiatable surface at which radiation from the position sensor is to be reflected by the material.

9. The method of non-contact detection of a physical characteristic of a material according to any one of claims 1 to 8, wherein, The material is a layered material having an outermost layer with a visually recognizable surface or a surface to be radiated or a radiatable surface, and the target reflection is related to a distance between each of the position sensors and a point or a location of the radiatable surface at which radiation from the position sensor is to be reflected by the material.

10. The method of non-contact detection of a physical characteristic of a material according to any one of claims 1 to 9, wherein, The position requirement of the scanning sensor relative to the material is predefined in relation to each of the target reflections, such that a correspondence or correspondence between each of the first sensed reflections and its associated target reflection corresponds to a satisfaction of the position requirement.

11. The method of non-contact detection of a physical characteristic of a material according to any one of claims 1 to 10, wherein, The correspondence or correspondence between each of the first sensed reflections and its associated target reflection is determined based on an absolute or non-absolute equality between each of the first sensed reflections and its associated target reflection, and / or depends on a distance function between each of the first sensed reflections and its associated target reflection.

12. The method of non-contact detection of a physical characteristic of a material of claim 11, wherein, The non-absolute equality corresponds to an equality plus / minus an acceptable error or tolerance.

13. The method of non-contact detection of a physical characteristic of a material according to any one of claims 1 to 12, wherein, Each of the first sensed interactions includes or is a sensed reflection-based interaction and / or a sensed transmission-based interaction.

14. The method of non-contact detection of a physical characteristic of a material according to any one of claims 1 to 13, wherein, The material has a layered structure comprising one or more layers, and the physical feature to be detected is a property of the layered structure.

15. The method of non-contact detection of a physical characteristic of a material of claim 14, wherein, The physical feature to be detected includes a thickness of at least one layer in the layered structure.

16. The method of non-contact detection of a physical characteristic of a material according to either of claims 14 or 15, wherein, The physical feature to be detected includes an electrical property of at least one layer in the layered structure, the electrical property being or including a complex refractive index, an electrical conductivity, an electrical resistance, or any combination thereof.

17. The method of non-contact detection of a physical characteristic of a material according to any one of claims 14 to 16, wherein, The physical feature to be detected includes a non-electrical property of at least one layer in the layered structure, the non-electrical property being or including a hardness, an adhesion, a formation of a defect, a formation of a void, a formation of a discontinuity, or any combination thereof.

18. The method of non-contact detection of a physical characteristic of a material of any one of claims 1 to 17, wherein, The position sensors and the scanning sensor are coupled to each other by a coupler, such that, in use, the scanning sensor illuminates the material at an illumination location or point, and the position sensors radiate the material at respective radiation locations or points around the illumination location or point.

19. The method of non-contact detection of a physical characteristic of a material of any one of claims 1 to 18, wherein, The positioning loop exits without satisfying the position requirement if a maximum number of positioning iterations has been reached or a maximum iteration time has elapsed.

20. The method of non-contact detection of a physical characteristic of a material of any one of claims 1 to 19, wherein, The step of obtaining an interaction property from the second sensed interaction comprises obtaining the interaction property based on a time domain processing and / or a frequency domain processing of the second sensed interaction.

21. The method of non-contact detection of a physical characteristic of a material of any one of claims 1 to 20, wherein, The step of obtaining an interaction property from the second sensed interaction comprises obtaining an energy of the second sensed interaction.

22. The method of non-contact detection of a physical characteristic of a material of any one of claims 1 to 21, wherein, The optimization loop is based on an optimization method aiming at finding a position of the sensor head, the optimization method optimizing an objective function representative of an evolution of the interaction property as a function of a positioning of the sensor head.

23. The method of non-contact detection of a physical characteristic of a material of claim 22, wherein, The optimization method is based on trying all possible positions of the sensor head to select a position maximizing the interaction property, or based on a gradient computation starting from an initial value of the interaction property, or based on a genetic algorithm, or based on a least square method.

24. The method of non-contact detection of a physical characteristic of a material of any one of claims 1 to 23, wherein, The scanning sensor is a terahertz-based scanning sensor, thus the operation of the scanning sensor comprises operating the scanning sensor to emit a terahertz-based illumination towards the material and to sense a terahertz-based interaction of the terahertz-based illumination with the material.

25. The method of non-contact detection of a physical characteristic of a material of any one of claims 1 to 24, wherein, The position sensors are laser-based position sensors, thus the operation of each of the position sensors comprises operating each of the position sensors to emit a laser-based radiation towards the material and to sense a laser-based reflection of the laser-based radiation with the material.

26. A multi-object method of contactless detection of a physical feature in a plurality of instances or objects of a material, the multi-object method comprising executing the method of any one of claims 1 to 25 for each of the instances or objects of the material to contactless detect the physical feature in each of the plurality of instances or objects of the material.

27. A computer program comprising program instructions for causing a computing system to execute the method of contactless detection of a physical feature of a material of any one of claims 1 to 26.

28. The computer program of claim 27, the computer program being embodied on a storage medium and / or carried on a carrier signal.

29. A system of contactless detection of a physical feature of a material by a sensor head and a positioner thereof, the sensor head comprising at least three position sensors and a scanning sensor coupled to each other, the scanning sensor having a position requirement with respect to the material, the position requirement being related to a target reflection associated to each of the position sensors, the system comprising: the sensor head, the positioner of the sensor head, a scanning sensor operator, a position sensor operator, a positioner operator, a positioning loop, an optimization loop, and a feature determiner; wherein, The system is configured to perform a positioning loop with positioning iterations by the positioning looper to converge the scanning sensor to the satisfaction of the position requirement, verify the satisfaction or non-satisfaction of the position requirement, and in case of non-satisfaction, perform an optimization loop with optimization iterations by the optimization looper until an optimized interaction property result corresponding to the satisfaction of the position requirement; and once the position requirement is satisfied, operate the scanning sensor by the scanning sensor operator to irradiate the material and first sense an interaction of the irradiation with the material, and detect the physical feature from the first sensed interaction by the feature determiner; wherein, each of the positioning iterations includes operating each of the position sensors by the position sensor operator to radiate the material and first sense a reflection of the radiation with the material, and determine a consistency or inconsistency between the first sensed reflection and a target reflection associated therewith, and in case of consistency, exit the positioning loop; in case of inconsistency, operate the positioners by the positioner operator to start a new iteration of the positioning loop with repositioning the sensor head in accordance with the determined inconsistency; and wherein, each of the optimization iterations includes operating the scanning sensor by the scanning sensor operator to irradiate the material and second sense an interaction of the irradiation with the material, obtain an interaction property from the second sensed interaction, and determine whether the interaction property is optimized or not optimized, and if not optimized, operate the positioners by the positioner operator to start a new iteration of the optimization loop with repositioning the sensor head in accordance with the interaction property; if optimized, exit the optimization loop, operate each of the position sensors by the position sensor operator to radiate the material and second sense a reflection of the radiation with the material, and update the target reflection from the second sensed reflection.

30. A computing system for non-contact detection of a physical feature of a material, the computing system comprising a memory and a processor, the computing system containing instructions stored in the memory and executable by the processor, the instructions comprising functions to perform the method of non-contact detection of a physical feature of a material according to any one of claims 1 to 26.

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