• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    A method of inspecting a surface of a tire in which the steps are carried out during which: an image of the relief of the sidewall of a reference tire is captured by means of an acquisition system , and the data obtained is transmitted to a processor, - by interaction of an operator with said processor, a parametrization of the main characteristics is carried out, and a mapping of the sidewall of the reference tire by cutting the image of the surface of the reference tire flank in several distinct areas of interest and is assigned to each of the areas of interest a specific control and registration algorithm, - one captures an image of a tire to be inspected, - automatically, one performs the operations during which, after performing a pre-processing of the image, the mapping is superimposed on the image of said tire to be inspected, and the control and control algorithms are implemented. spacing specific to each of the areas of interest of the tire to determine compliance.
    公开号:FR3039684A1
    申请号:FR1557142
    申请日:2015-07-27
    公开日:2017-02-03
    发明作者:Regis Vinciguerra；Steve Bourgeois；Alexandre Joly；Alexandre Chariot
    申请人:Michelin Recherche et Technique SA Switzerland ；Compagnie Generale des Etablissements Michelin SCA；Michelin Recherche et Technique SA France；
    IPC主号:
    专利说明:

    The invention relates generally to the field of tire manufacturing, and is more particularly in the context of tire appearance control operations in progress or at the end of the manufacturing process, in order to determine the conformity of said tires with respect to control references.
    The industrial means of automatic tire control developed by the manufacturers and intended in particular to assist the operators in charge of the visual control, make extensive use of image processing techniques.
    The methods used to perform these treatments consist, as a rule, in comparing an image in two or preferably in three dimensions of the surface of the tire to be inspected, with a reference image in two and preferably in three dimensions of the surface of said tire.
    One of the steps of this process is, in a known manner, to acquire the three-dimensional image of the surface of the tire, using, for example, means based on the principle of optical triangulation, for example a 2D sensor coupled to a laser-type lighting source. The two-dimensional image is obtained using the same capture means and then consists of a simple photograph of the surface. This two-dimensional image can also be obtained by any means of acquisition of the linear camera type or calculated at the same time as the three-dimensional image in the case of optical triangulation from the intensity of the laser line projected on the tire. The image of the tire surface is formed by the set of digital data from the capture of the three-dimensional and two-dimensional image. This data from the sensor is transmitted to a processor whose memory contains code instructions able, when executed, to process very large data volumes.
    The following steps consist in carrying out a number of pre-treatments making it easier to use the data forming the image of the surface of the tire.
    The process continues to recalibrate the image of the raised surface of the tire to be inspected with the image of the reference relief surface. This step proves particularly complex because of the local deformations generated by the release of the stresses at the outlet of the baking mold. This reference image may be derived from a CAD model, or from a model that was used to design the mold from which the tire is derived, or even from a reference tire considered to be free of anomalies.
    Thus, the publication WO2009077539 proposes to determine an affine transformation by seeking the coincidence of previously identified characteristic points on the surface of the tire to be inspected and on the reference surface.
    The publication WO2012 / 055748 relies on the use of the particular properties of the B-spline surfaces to locally coincide said characteristic points.
    The publication WO2012 / 052300 proposes a method of registration of the patterns of a tread by matching the sequenced basic patterns in a known manner by using the basic patterns comprising a wear indicator forming a characteristic and easily identifiable image.
    The process ends using numerical methods of inspection and troubleshooting, or by simply comparing the image of the tire to be inspected with the reference image.
    The publication WO2013 / 045593 proposes a method for processing two-dimensional images of smooth surfaces by morphological analysis. The publication WO2012 / 143197 focuses more particularly on the treatment of non-measurement points generated by the shadow zones formed by the vents. The applications FR1462901 or FR1462898, not yet published, propose algorithms for detection and analysis of conformity of the striations present on the surface of the tire sidewall which are less demanding in computation time than traditional methods by Fourier transformation or by analysis. of the three-dimensional image.
    However, we observe that these tools, give good results for the analysis of the specific relief elements of the tire surface such as drawings or text areas, or the sculptures, the vents generated by the venting means of the tire. mold, smooth areas, streaks or text areas appearing on removable inserts.
    All these algorithms have the particularity of being consumers of computing time, in particular if they are deployed over the entire surface of the tire to be inspected. The object of the invention is to make a contribution that makes it possible to reduce the calculation time required for the inspection of tires at the end of the manufacturing process by allowing the identification of distinct areas of interest on which algorithms are used. specific will be used.
    According to the invention, the method of inspecting a surface of a tire to be inspected by comparison with a reference surface of a reference tire, said surfaces comprising markings or elements in relief, is characterized in that steps are taken in which: by means of an acquisition system, an image of the reference surface of a reference tire taken from the manufacture and considered to be in conformity is captured, and transmitted the data obtained to a processor containing in its memory coded instructions which, when executed, make it possible to carry out the steps of the method, an interaction of an operator with said processor is carried out a parameterization of the main characteristics, and a mapping of the reference surface of the reference tire by cutting the image of the reference surface of the reference tire e n several distinct areas of interest, each of the areas of interest comprising a characteristic shape or relief, the areas of interest being separated by boundaries, and each of the previously identified areas of interest is assigned one or more selected registration and control in a collection of algorithms previously constituted and stored in a memory of said processor, it is captured, using said acquisition system, an image of the relief of the surface to inspect a tire to be inspected, and separate from the reference tire, and transmit the data obtained to the processor, automatically, and based on the main characteristics previously defined and stored in the memory of the processor, said processor performs, by executing the coded instructions, the operations at the during which: o At least one pretreatment of the acquired image is performed, where one superimposes said mapping on the image of the surface to be inspected of said tire to be inspected so as to determine the areas of interest of the tire to be inspected where one implements the registration and control algorithms specific to each of the areas of interest of the tire to inspect, to determine compliance.
    The method thus provides, in a preparatory manner, a long and sometimes complex parameterization of the reference envelope, so as to define the most optimal parameters forming the main characteristics of the areas of interest of the reference tire, and to choose carefully the algorithm or algorithms best suited for each of these areas of interest.
    This preliminary work makes it possible to implement, during the current inspection phase, only the treatments best suited to the registration and then the control of a particular area of interest. These treatments are chosen to be not very complex and particularly efficient, mainly when they are applied to homogeneous zones, in the sense of the characteristics of the zone of interest concerned. The invention therefore makes it possible, for a given computing power of the processor, to reduce the calculation time necessary for estimating the conformity of an envelope during the control phase, and to make it possible to carry out this control at a compatible rate. with the rhythm of industrial manufacturing.
    A surface of the tire is here understood to mean a surface formed by all or part of the surfaces formed by the inner surface, or by the external surface of the tire comprising the sidewall, the shoulders, the bead or the tread. It goes without saying that when the reference surface of the reference tire represents only a part of the tire surface such as the sidewall, the tread or the inner part, the surface to be inspected of the tire to be inspected represents the surface on which the tire is to be inspected. an identical part of the tire is respectively the sidewall, the tread or the inner part.
    The method according to the invention may also comprise in isolation or in combination the following characteristics: the reference tire and the tire to be inspected come from the same mold. the pretreatment of the acquired image comprises one or more treatments chosen from the following algorithms: a flattening of the radial profile of the surface. o the conversion of the polar coordinates expressed with respect to the axis of rotation of the tire of the image of the surface of the tire sidewall into Cartesian coordinates, o corrections related to the defects of the optical system performing the acquisition such as the correction of the localized optical deformations or the correction of shadow areas. the relief image of the tire surface is formed by a two-dimensional grayscale or color image, and a three-dimensional grayscale image in which at each point of the image is assigned a proportional gray level value at the topographic elevation of this point. the parameterization of the main characteristics of the reference tire comprises data selected from the following characteristics: o a sum of the value of the gray levels of the columns and lines of the three-dimensional raw or filtered image, forming a one-dimensional signature, o a curvature average of the flank, o a shape of the outline of a characteristic relief present in a given area of interest, forming characteristic two-dimensional images, o one or more characteristic points of a characteristic relief present in an area of interest, o a geometric moment, o one or more geometrical measurements between the characteristic points such as distances or angles, o a response to a morphological operator on the basis of a structuring element of given shape and orientation, o an image of reference of the orientation of steepest elevation gradients of a blowtorch e, o morphological filters and responses to texture type characterizations. the collection of registration algorithms comprises at least one registration method for registering the relief of an area of interest of the reference surface with the relief of the area of interest of the surface to be inspected. the method of registration is chosen, in order of increasing complexity, from one or more of the following methods: o mapping of one-dimensional signatures and angular registration, o mapping of characteristic points, o mapping of characteristic images, o Three-dimensional relief mapping, the algorithm collection comprises first-level algorithms based on analyzes such as the comparison of the contours of the characteristic images, the comparison of the geometric measurements between the characteristic points, the comparison of the geometric moments. the collection of control algorithms comprises at least one specific method for analyzing the areas of interest in which the characteristic relief is formed by one or more alphanumeric characters. the collection of control algorithms comprises at least one specific method for analyzing the areas of interest in which the characteristic relief is formed by streaks. the collection of control algorithms comprises at least one specific method for analyzing the areas of interest in which the characteristic relief is smooth. the collection of control algorithms comprises at least one specific method for analyzing the areas of interest in which the characteristic relief is formed by a removable wafer. the collection of control algorithms comprises at least one specific method for analyzing the areas in which the characteristic relief comprises a vent. the collection of control algorithms comprises at least one specific method for analyzing the areas of interest in which the characteristic relief is formed by the tread. the collection of control algorithms comprises at least one specific method for analyzing the areas in which the characteristic relief comprises a wear indicator. the collection of control algorithms comprises at least one specific method for analyzing the areas in which the characteristic relief comprises texture. The invention finally comprises a computer program comprising suitable code instructions, when executed on a computer to control the implementation of the steps of the method above. The invention will be better understood on reading the appended figures, which are provided by way of examples and are in no way limiting, in which:
    Figure 1 schematically shows the coordinate change operation performed during pretreatment of the image of the surface. FIG. 2 schematically represents the operation of flattening the image made during the pretreatment of the image of the surface.
    Figure 3 illustrates an angular registration operation performed during pretreatment of the image of the surface.
    Figure 4 schematically shows a search and a matching of the characteristic points.
    Figures 5 and 6 illustrate the shape and positioning of a mapping on a sidewall of a tire.
    Fig. 7 is a schematic view of a tread formed from the juxtaposition of elements having basic patterns.
    As discussed above, the image of the tire surface may be a two-dimensional image, similar to a photograph, and representative of the appearance of the surface. This image can be a black and white or color image. It reflects the color or the level of gray as well as the shine.
    We then obtain a set of points, or pixels, arranged in a plane, whose gray level corresponds to the light reflected by the surface of the tire.
    In addition to techniques based on optical triangulation, the acquisition of the topographic image of the flank surface can be performed according to the conventional stereovision technique, in which it is proposed to use two separate cameras dedicated to acquisition of terrain data. The two cameras are positioned to take a shot of the surface to be inspected at different angles of view. Still according to this technology, it is appropriate, after the step of acquiring the two-dimensional images from the two cameras, to match these images so as to associate at a given point of the surface to inspect the image points formed in each images made by each of the cameras. The three-dimensional coordinates of the point of the surface are then calculated by triangulation, determining, after calibration of the cameras, the angles of views different from this point of the surface seen by the two cameras.
    A scattered point cloud is then obtained in the three-dimensional space and representative of the surface of the flank.
    A device capable of making two shots simultaneously in a single rotation of the tire is described by way of example in the publication WO 2009/077534.
    The raw data of the two-dimensional image and the three-dimensional image which together form the image of the tire surface, and which are obtained by the acquisition system, are then transmitted to a processor containing the coded instructions which, when they are executed by said processor, make it possible to implement the various steps of the method.
    To facilitate the implementation of subsequent processing, a number of image preprocessing operations are generally performed. The development of this pretreatment is done by an operator interacting with the processor, using the digital data from the reference image of the reference tire.
    To carry out this pretreatment, the operator can use data previously entered in the processor memory such as CAD design data associated with the tire being processed, as well as specific algorithms whose processing steps are not made. not within the scope of the present invention.
    This first work makes it possible to determine a set of main characteristics related to the particular dimension of the tire. These main characteristics are intended to be reused by the processor to perform the pretreatment or execute the control algorithms of each of the envelopes to inspect.
    The pretreatment may comprise a first operation which consists in recalibrating the two-dimensional image, so as to correct the shadow zones generated by the variations of illumination during the shooting, or the deformations related to the optical system, and which are specific to the acquisition system used. These shadows or deformations are reproduced at each shot.
    During the analysis of the image of the reference tire, the operator will then determine the compensations to be made and record these compensations in the main characteristics of the dimension, so as to apply the same compensations to all the tires to inspect the same dimension as the reference tire.
    For the sake of convenience, the three-dimensional image is also reworked.
    It is arranged for the three-dimensional coordinates x, y, z of surfaces to be analyzed to be expressed in an orthonormal frame ΟΧ, ΟΥ, OZ in which the axis OZ is substantially coincident with the axis of rotation of the tire. It is then easy to convert the coordinates x, y, z by projection in the plane OXY and to change the Cartesian coordinates x, y in the plane OXY into polar coordinates of type ρ, Θ, as illustrated in FIG.
    We also proceed to what is commonly called a flattening of the profile. To do this, the average profile of the curvature of the surface in a radial plane is determined by projecting all the points in the plane formed by the axes OZ and OX ', as illustrated in FIG. 2, which corresponds to a projection in a radial plane. The shape of the average radial profile will be given by the shape of the point cloud in this radial plane, from which we can extract a mean curve by averaging the values in a direction OZ. The surface obtained by deploying again this average radial profile corresponds substantially to the surface of the tire on which there would be no marking in relief.
    It then suffices, for each value of the angle Θ to subtract the value of this average radial profile from the coordinates expressed in the plane OX'Z to obtain a flattening of the unwound surface determined above, and in which, alone, the relief elements have a value along the axis OZ.
    Flattening can also be done by following the profile of the surface according to a determined pattern, for example a line in which the value of p is constant, and by detecting the localized variations of the profile, significant of the embossed markings present on said area. The juxtaposition of these lines also gives a flat surface on which only the relief elements appear.
    Once determined, this average profile is recorded in the list of main characteristics of the dimension, in order to be reused for the flattening of the tires to be inspected.
    By assigning a value of gray level to the value along the axis OZ and representing the elevation of the elements in relief, we obtain a two-dimensional image of the surface, on which the relief elements are visually detached from the color of the average surface. This latter simplification can be done with a similar result on the flattened surface according to one of the methods described above. At the next stage of his work, the operator, always interacting with the processor, draws up a map of the surface and determines the limits of the different areas of interest. It then assigns to each of these areas of interest the specific registration and control algorithms best suited to the specific characteristics of these areas, as illustrated in Figure 5. This determination can be automated, for example if the data of CAD design of the mold used to bake the tire, are available.
    The boundaries between the areas of interest Z, having different morphological characteristics, and likely to use different registration and control algorithms are thus defined. These boundaries define a map, illustrated in Figure 6.
    This mapping, as well as the link with the specific algorithms are among the main characteristics of the tire.
    When analyzing the surface to be inspected of the tire to be inspected, and in order to be able to compare the image of the surface of the tire to be inspected with the image of the surface of the reference tire, it is necessary to proceed to a mapping recalibration.
    The registration strategy consists in using data of increasing complexity based on information initially obtained from a one-dimensional signature of the image, then from the two-dimensional image and, if necessary, from the three-dimensional image of the surface of the image. pneumatic. This strategy makes it possible to graduate the complexity of the data / algorithms used, in parallel with a reduction in the areas concerned:
    Thus, the one-dimensional signature is adapted to treat the whole surface, the two-dimensional images make it possible to treat areas of very homogeneous or little relief interest, and the three-dimensional images make it possible to register areas of interest comprising important reliefs and varied.
    For the angular registration Δα of these two images, a simple way of proceeding consists in making a one-dimensional signature of the reference image by summing raw data formed by the value of the gray levels of the pixels of a line of the image. two-dimensional image or preferably of the three-dimensional image of this reference tire. We then obtain a 1D curve.
    To improve the relevance of this signature, it is also possible to perform a prior filtering of the image by considering for example the gray level gradients or the gray level averages on each of the rows or each column of the picture.
    By carrying out the same operation on the tire to be inspected, a second signature is obtained and, by sliding the two signatures over each other so as to match them, a value of the circumferential offset to be obtained is obtained. angularly matching the image of the tire to be inspected angularly with the image of the reference tire.
    A similar operation can be performed by summing the gray level values, gross or filtered, of a column when it is necessary to perform a registration in the radial direction.
    The 1D, radial and circumferential signatures, raw or filtered, of the reference tire are then part of the main characteristics.
    When analyzing the surface of the tire to be inspected, this first one-dimensional registration, which is generally carried out during the pretreatment phase, makes it possible to project the map on the surface of the tire to be inspected to define the corresponding zones, and to apply to these zones the algorithm of registration and control predefined by the operator and corresponding best to the specificities of the relief of the zone.
    Thus, another more complex registration operation, this time using the two-dimensional image of the tire surface, consists in determining in the reference image of the reference tire, a few easily detectable characteristic points so as to be able to match them. with the same reference points of the area to be inspected of the tire to be inspected as shown in Figure 4.
    The characteristic points may be replaced by the characteristic relief contours, forming characteristic thumbnails, and which are portions of the two-dimensional image of the area of interest considered.
    This mapping operation can be used for the registration of the entire surface but preferably applies within a particular area of interest which may have been previously determined by a one-dimensional angular registration step, in order to allow the use of simple local transformations of the translations type. By way of example, there may also be mentioned a specific registration algorithm more particularly adapted to the zone of interest formed by the tread of the tire, and whose sculpture is formed by the assembly of circumferentially juxtaposed elements (ABCU). as shown in Figure 7, and separated from each other by borders of identical shapes. These elements have basic patterns, in reduced number accurately and known sequence, comprising at least one base pattern on which are placed wear indicators which are associated with a characteristic point of this basic pattern.
    According to this algorithm, the wear indicators present on the image of the tread of the tire to be inspected are identified. Subsequently, the subset wear indicators corresponding to the basic pattern comprising wear indicators are grouped together and the characteristic point of each of these subassemblies is determined. A sequence of distances is then determined by calculating the distances between the characteristic points of each of the subsets of wear indicators identified on the surface of the tread to be inspected, and this sequence of distances is made to coincide with the known sequence. distances between the characteristic points of the basic patterns. Finally, it is projected on the surface to be inspected the shape of the boundary between the elements according to the known sequence of positioning of said elements.
    The sequence of distances between the characteristic points of the basic motifs of the sculpture is one of the main characteristics.
    A registration algorithm of this type is described by way of example in the publication WO 2012 052300. The control algorithm of the tread can then be performed by comparing the three-dimensional surface of the three-dimensional image of the surface of the tread. the tread of the tire to be inspected with the image of the three-dimensional surface of the tread of the reference tire.
    Still as an example, and to illustrate the principles of the method that is the subject of the present invention, the areas of interest Zi Ζι2, Ζι3, Zi4, Zi5 of the figure are areas of interest arranged on the sidewall of the tire and containing reliefs comparable to drawings for which specific registration and control algorithms have been developed.
    The purpose of these registration and control algorithms is to match, in the most accurate way possible, the three-dimensional surface of the envelope to be inspected and the three-dimensional surface of the reference envelope, so as to be able to determine, by difference , molding anomalies. It is therefore necessary to carry out a controlled deformation of the surface to be inspected to take account of very slight changes in position generated by the release of the stresses at the moment of demolding, as has already been mentioned.
    These registration and control algorithms can be established on the association, with each graphic element of the reference surface, of an elementary B-Spline surface type control grid comprising characteristic points Py. Once this association is achieved, the contour of each graphical element of the reference surface is deformed by modifying the position of the characteristic points of the elementary B-Spline surface so as to minimize the distances between the contour of the graphical element of the reference surface. the reference surface and the corresponding contour of the graphic element of the surface to be inspected.
    A registration and control algorithm of this type is described by way of example in the publication WO 2012 055748.
    Another way to proceed is to search, iteratively, for an affine transformation function comprising a homothety whose ratio has an absolute value different from 1. This transformation function is applied to the characteristic points of the reference surface, such so that the value representing the sum of the distances between each of the characteristic points of the reference surface, transformed by means of the transformation function, and the points of the surface to be inspected which are matched to them, is minimal.
    A specific registration and control algorithm of this type is described in more detail in WO 2009/077539.
    Once this adjustment has been made, the differences between the reliefs of the zone comprising drawings of the reference tire and the relief of the same zone belonging to the tire to be inspected are sought.
    The characteristic points chosen by the operator to perform these precise readjustments are integrated in the main characteristics of the reference tire, and stored in the memory of the processor.
    Areas of interest Z2, Z3, Z4 are particular areas containing a vent. The vents, also called teats, are caused by venting devices placed in the mold to promote the flow of occluded gases at the time of molding. Each mold has a venting system of its own.
    These vents cause shadow areas, and therefore measurement anomalies around the surface where they are implanted. A specific algorithm allows to reconstruct the surface, usually smooth, around the foot of the vent. From the three-dimensional image of the surface to be inspected, the algorithm searches the areas of the surface comprising pixels whose gray level value is below a given threshold, and determines the boundaries of a bounding box. Within the bounding box and for a given line secant of the zone containing pixels whose gray level value is less than a given threshold, each of said pixels is assigned a gray level value equal to the average value of gray level of a set formed by the pixels of a reference segment belonging to said line, and placed close to the zone considered.
    It is also possible to determine the area of the pixel zone having a gray level value below the given threshold and, when the area of this zone exceeds a given threshold, the angle between the main axis of said zone is determined. and the direction of the pixel lines, as well as the center of gravity of said area. The position of a vent at one of the ends of the main axis of said zone is then sought, and the zone is oriented in a direction extending along the zone and originating from the foot of the vent. . At each of the secant lines of the zone containing the pixels having a gray level value lower than the given threshold, a reference segment is arranged on the side of the main axis of said zone corresponding to the angular sector forming a positive angle with the direction of the shadow area, and assigning the average gray level value of the pixels of the reference segment to all the pixels of the line containing said reference segment and lying between the middle of the reference segment and the intersection of said pixel line with the contour of the foot of the vent.
    This specific algorithm is described in more detail in WO 2012/143197.
    By determining in advance the position of the vents it is then possible to implement the control algorithm described briefly above only in the only zones in which a vent is present, and thereby to treat only a reduced volume of data with a more complex algorithm.
    Areas of interest Z6, Z7, Z8, Z9, Z10, Zn are areas containing one or more alphanumeric characters.
    To ensure the conformity of the markings, it is then sufficient to implement a known specific algorithm type optical character recognition (OCR).
    Among these areas of interest, certain zones, such as the zone of interest Z6, are of a particular nature in that the markings they comprise are formed by removable plates inserted in the mold. These pads are changed daily or weekly, and may vary in alignment with the mold surface. This results in localized variations of relief subject to special tolerancing.
    In streak areas, such as areas of interest Zi6, Z17, Zi8 or Z19, the undulations of the surface are not precisely described.
    The specific algorithms allowing the analysis of the conformity of these zones of striations are based on the use of the tools of the morphological analysis of the two-dimensional or three-dimensional image of the surface of the tire. These algorithms provide for determining at least one dilation of a basic representation comprising a streak zone so as to obtain an expanded representation, and to determine at least one erosion of the basic representation so as to obtain an eroded representation, and to determine a difference between the dilated representation and the eroded representation so as to obtain a difference representation showing the anomalies.
    These dilations and erosions use structuring elements whose size and orientation must be adjusted according to the size and orientation of the streaks.
    It will be observed that the streaks of the zones of interest Zi6 and Z17 have a direction reversed with respect to the streaks of the zones of interest Zi8 and Zi9. The operator therefore adapts the parameters of the structuring elements to the ridges of each of the striation zones of the reference tire and records these main characteristics in the memory of the processor for each of the zones considered.
    These structuring elements, as well as the specific responses they generate on the reference surface, are among the main characteristics. The application of these specific algorithms only to previously identified streak zones makes it possible once again to use more complex algorithms on reduced data volumes.
    Zone of interest Z19 is a smooth zone in which no relief is supposed to be present.
    The registration algorithms attributed to these zones can therefore be extremely simple and be limited, for example, solely to one-dimensional registration as described above.
    The anomalies present on these surfaces may be localized molding defects or hollow variations caused by localized deformations of the carcass reinforcement ply, or else detectable spots because of the highlighting they cause.
    Also, the specific control algorithms particularly adapted to these surfaces have been developed to control compliance.
    A first specific control algorithm is described for example in the publication WO2012 / 156262. This control algorithm is based on the analysis of the three-dimensional gray-scale image of the surface.
    According to this publication, the steps are carried out in which, using linear structuring elements of successively increasing sizes and oriented in the circumferential direction, a series of morphological openings of the image of the surface of the surface is made. pneumatic. Subtracting from the value of the image obtained after morphological opening with a given structuring element, the value of the image obtained after morphological opening with the structuring element of immediately smaller size so as to obtain a succession of flattened images by difference, by initializing the procedure by subtracting the image obtained using the structuring element of smaller size. Finally, the images flattened by difference are thresholded to obtain binary images, and the set-up union of the values of each of the binary images is done to obtain a final binary image, in which only the marking patterns appear in relief. .
    Then, the disjoint patterns are identified in the binary image of the surface, and the image of the bulge of said surface, in which the relief markings are made, is determined by difference with the starting image of the tire surface. have been removed and where only the localized deformations of the surface mentioned above remain.
    It will be observed here that this type of algorithm can also be used for the determination of the average radial profile for performing the flattening during the preprocessing phase.
    Another control algorithm, particularly suitable for the control of internal surfaces, is also based on the analysis of the texture of the three-dimensional image of the surface and also uses the tools of morphological analysis. A specific algorithm of this type is described for example in the publication WO 2013/045593.
    According to this publication, via factorial spaces in which the data are formed by morphological filters and the variables are formed by the multivariate images of the tire surface with previously identified anomalies, the most suitable series of morphological filters are determined. to highlight said anomalies. These series of filters are then applied to the image of the tire to be inspected and, using a classifier, the presence of these anomalies is detected.
    These morphological filters, as well as the responses to texture-type characterizations that they generate on the reference surface, are among the main characteristics.
    It will be observed here that certain nonconformities are not specific to the nature of the relief coming from the reliefs in hollow of the mold. This is the case, for example, of air inclusions between two layers of internal materials, which can be detected because of the localized deformation that they produce on the surface.
    A specific algorithm for detecting these anomalies is described in publication WO 2014/198777.
    According to this algorithm, from the three-dimensional digital image of the surface of a tire to be inspected, an image of the orientation of the elevation gradients of the surface in which is assigned to each point of the image a a gray level value proportional to the angle formed with a direction given by the projection in the plane of the image of a non-zero standard vector substantially corresponding, at this point, to the gradient vector tangent to the surface and oriented in the direction of the steepest slope. A filtered image of the orientations is then determined by transforming the image of the orientation of the elevation gradients with the aid of a digital filter able to select the areas comprising structures similar to a reference image of the orientation. elevation gradients of steeper slope of a blister.
    This reference image of the orientation of steepest elevation gradients of a blister that is in the form of a circumferential grayscale gradient is then considered a major feature of the dimension, and stored in the processor memory.
    For the inspection of the tires to be inspected, the operator can then choose to have the processor execute this specific algorithm in all the zones or only on certain specific zones that are more sensitive to the appearance of these air inclusions.
    Of all the specific control algorithms made available to the operator and stored in the processor's memory, some may be considered as first-level algorithms. These particular algorithms are not very greedy in terms of computation time and make it possible to quickly identify if the zone in which they are implemented includes an element that can give rise to doubt about the presence of a defect. It is then wise to implement these so-called first-level algorithms and to decide, depending on the result obtained, whether or not it is appropriate to launch one of the specific algorithms that is more resource-intensive.
    Among these reduced algorithms we can for example calculate, for a relief similar to a drawing, the geometric moment or the moment of inertia of the surface defined by the contours of this drawing with respect to a characteristic point. More specifically, the calculation of the Zernike moment as described in the publication "Invariant Image Recognition by Zernike Moments" by Alizea Khotanzad and Yaw Hua Hong, IEEE Transactions and Pattern Analysis and Machine Intelligence Vol 12 No. 5 May 1990, also adapted to detect first-level errors in drawing areas, but also in areas containing alphanumeric characters.
    An overlap comparison between the contour of the reference image present in the area of interest of the reference tire and the contour of the image, present in the same area, of the tire to be inspected may also prove to be a valuable aid . The contour of the images can be obtained, in known manner, from the two-dimensional image or the three-dimensional image of the surface.
    More simply, it is also possible to calculate distances between certain well-chosen characteristic points, or to make geometric measurements such as the calculation of the angles formed by lines passing between these points.
    The shape of the contours, the geometric moments, the geometrical measurements, the characteristic points of the reliefs of the reference tire, are considered as main characteristics and recorded in the memory of the processor. The set of specific or reduced registration and control algorithms form a collection of algorithms which is also stored in the memory of the processor. At the end of this analysis of the surface of the reference tire produced by the operator interacting with the processor, an enriched base is obtained in which each zone of interest of the tire is associated with one or more algorithms of the tire. calibration and control characteristics for which the choice of the main characteristics is determined.
    During the inspection in current running of the tires coming from the same mold as the reference tire, it suffices then to carry out successively the pretreatment operations as described above, to recalibrate the image of the surface and to overlay the cartography on the image of the tire to be inspected so as to identify the areas of interest.
    The processor then automatically implements the specific registration and control algorithms defined for each of the areas using the main characteristics assigned to these algorithms and previously stored as explained above.
    The result of the implementation of these calculations makes it possible to determine the conformity of the tire. The set, formed by the image of the reference surface of the reference tire, the main characteristics, the mapping with the optimal principle of registration associated with it, and the choice of registration and control algorithms to implement for each of the areas of interest, is the basic model for optimally performing control of a tire to be inspected from the same mold as the reference tire.
    This basic model must be adapted every time an intervention such as the drilling of a vent or the change of a plate, is performed on the mold.
    With minor modifications, such as the position of the vents, this basic model can easily be adapted to serve as a basic model for a reference tire from a different mold of the same dimension.
    With a few additional adaptations, it can also serve as a basic model for the different dimensions of the same tire model of different diameter.
    Finally, the collection of specific algorithms can be used to create basic models for tires of different sizes.
    We thus obtain a hierarchy of basic models that group together according to the similarity between the different algorithms used.
    权利要求:
    Claims (17)
    [1" id="c-fr-0001]
    A method of inspecting a surface of a surface to be inspected from a tire to be inspected by comparison with a reference surface of a reference tire, said surfaces comprising markings or elements in relief, characterized in that implementing the steps in which: using an acquisition system, an image of the reference surface of a reference tire taken from the manufacture and considered to be in conformity is captured, and transmits the obtained data to a processor containing in its memory coded instructions which, when executed, enable the steps of the method to be performed, an interaction of an operator with said processor is carried out, a parameterization of the main characteristics, and a mapping the reference surface of the reference tire by cutting the image of the reference surface of the reference tire a plurality of different areas of interest, each of the areas of interest comprising a characteristic shape or relief, the areas of interest being separated by boundaries, and each zone of interest previously identified is assigned one or more algorithms of registration and control chosen from a collection of algorithms previously constituted and stored in a memory of said processor, it is possible to capture, by means of said acquisition system, an image of the relief of the surface to be inspected from a tire to be inspected. , and separate from the reference tire, and transmit the data obtained to the processor, automatically, and based on the main characteristics previously defined and stored in the memory of the processor, said processor performs, by executing the coded instructions, the operations during which: o At least one pretreatment of the acquired image is performed, o is sup erases said mapping on the image of the surface to be inspected of said tire to be inspected so as to determine the zones of interest of the tire to be inspected, where the registration and control algorithms specific to each of the areas of interest of the tire are used. to be inspected, to determine compliance.
    [2" id="c-fr-0002]
    2. The inspection method according to claim 1, wherein the reference tire and the tire to be inspected come from the same mold.
    [3" id="c-fr-0003]
    3. An inspection method according to claim 1, wherein the pretreatment of the acquired image comprises one or more treatments chosen from the following algorithms: a flattening of the radial profile of the surface. the conversion of the polar coordinates expressed with respect to the axis of rotation of the tire of the image of the surface of the tire flank in Cartesian coordinates, corrections related to the defects of the optical system performing the acquisition such as the correction of the optical deformations localized or the correction of shadow areas.
    [4" id="c-fr-0004]
    4. An inspection method according to one of claims 1 to 3, wherein the image of the relief of the surface of the tire is formed by a two-dimensional image in gray level or in color, and a three-dimensional image in gray level wherein at each point of the image is assigned a gray level value proportional to the topographic elevation of that point.
    [5" id="c-fr-0005]
    5. Inspection method according to one of claims 1 to 4, wherein the parameterization of the main characteristics of the reference tire comprises data selected from the following characteristics: a sum of the value of the gray levels of the columns and lines of the three-dimensional gross or filtered image, forming a one-dimensional signature, a mean curvature of the flank, a shape of the outline of a characteristic relief present in a given area of interest, forming two-dimensional characteristic thumbnails, one or more points characteristics of a characteristic relief present in an area of interest, a geometric moment, one or more geometrical measurements between the characteristic points such as distances or angles, a response to a morphological operator on the basis of a structuring element of shape and orientation data, a reference image of the orientation of he steepness gradients of steeper slope, morphological filters and responses to texture type characterizations.
    [6" id="c-fr-0006]
    6. An inspection method according to claim 5 wherein the collection of registration algorithms comprises at least one registration method for registering the relief of an area of interest of the reference surface with the relief of the area. of interest of the surface to be inspected.
    [7" id="c-fr-0007]
    7. The inspection method as claimed in claim 6, in which the registration method is chosen, in order of increasing complexity, from one or more of the following methods: mapping of the one-dimensional signatures and angular registration, mapping of the characteristic points, mapping of characteristic thumbnails, mapping of reliefs into three dimensions.
    [8" id="c-fr-0008]
    The inspection method as claimed in claim 7, wherein the collection of algorithms comprises first level algorithms based on analyzes such as the comparison of the contours of the characteristic thumbnails, the comparison of the geometric measurements between the characteristic points, the comparison. geometric moments.
    [9" id="c-fr-0009]
    9. An inspection method according to claim 7, wherein the collection of control algorithms comprises at least one specific method for analyzing the areas of interest in which the characteristic relief is formed by one or more alphanumeric characters.
    [10" id="c-fr-0010]
    The inspection method according to claim 7, wherein the collection of control algorithms comprises at least one specific method for analyzing the areas of interest in which the characteristic relief is formed by streaks.
    [11" id="c-fr-0011]
    11. The inspection method according to claim 7, wherein the collection of control algorithms comprises at least one specific method for analyzing the areas of interest in which the characteristic relief is smooth.
    [12" id="c-fr-0012]
    12. An inspection method according to claim 7, wherein the collection of control algorithms comprises at least one specific method for analyzing the areas of interest in which the characteristic relief is formed by a removable wafer.
    [13" id="c-fr-0013]
    The inspection method of claim 7, wherein the collection of control algorithms comprises at least one specific method for analyzing the areas in which the characteristic relief comprises a vent.
    [14" id="c-fr-0014]
    14. An inspection method according to claim 7 wherein the collection of control algorithms comprises at least one specific method for analyzing the areas of interest in which the characteristic relief is formed by the tread.
    [15" id="c-fr-0015]
    The inspection method according to claim 7, wherein the collection of control algorithms comprises at least one specific method for analyzing the areas in which the characteristic relief comprises a wear indicator.
    [16" id="c-fr-0016]
    The inspection method of claim 7, wherein the collection of control algorithms comprises at least one specific method for analyzing areas in which the characteristic terrain comprises texture.
    [17" id="c-fr-0017]
    17. A computer program comprising code instructions adapted, when executed on a computer, to control the implementation of the steps of the method according to one of claims 1 to 16.
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    同族专利:
    公开号 | 公开日
    WO2017017371A1|2017-02-02|
    US10346971B2|2019-07-09|
    US20180197285A1|2018-07-12|
    FR3039684B1|2018-08-10|
    CN107851314A|2018-03-27|
    EP3329460A1|2018-06-06|
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    法律状态:
    2016-07-21| PLFP| Fee payment|Year of fee payment: 2 |
    2017-02-03| PLSC| Publication of the preliminary search report|Effective date: 20170203 |
    2017-07-24| PLFP| Fee payment|Year of fee payment: 3 |
    2018-07-25| PLFP| Fee payment|Year of fee payment: 4 |
    2020-04-10| ST| Notification of lapse|Effective date: 20200306 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1557142|2015-07-27|
    FR1557142A|FR3039684B1|2015-07-27|2015-07-27|OPTIMIZED METHOD OF ANALYSIS OF THE CONFORMITY OF THE SURFACE OF A TIRE|FR1557142A| FR3039684B1|2015-07-27|2015-07-27|OPTIMIZED METHOD OF ANALYSIS OF THE CONFORMITY OF THE SURFACE OF A TIRE|
    EP16760124.4A| EP3329460A1|2015-07-27|2016-07-26|Optimised method for analysing the conformity of the surface of a tyre|
    PCT/FR2016/051941| WO2017017371A1|2015-07-27|2016-07-26|Optimised method for analysing the conformity of the surface of a tyre|
    CN201680043971.1A| CN107851314A|2015-07-27|2016-07-26|For the method for the optimization for analyzing surface of tyre uniformity|
    US15/741,378| US10346971B2|2015-07-27|2016-07-26|Optimized method for analyzing the conformity of the surface of a tire|
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