Compagnie Generale Des Etablissements Michelin

Michelin Recherche Et Technique S.a.

Compagnie Generale Des Establissements Michelin

Compagnie Generale Des Etablissments Michelin

Societe Detechnologie Michelin

Alexandre Joly

Jean-Paul Zanella

Steve Bourgeois

Régis Vinciguerra

Guillaume Noyel

Gérard Bor

Christian Leobal

Claire Moreau

François Gaspard

Alexandre Chariot

A method for inspecting a tire's surface includes: capturing a reference image of a reference tire's surface relief elements and transmitting data of the reference image to a processor; parameterizing main characteristics of the reference image via interaction of an operator with the processor; producing a reference map of the surface relief elements by dividing the reference image into a plurality of reference zones of interest; assigning a specific registration and checking algorithm to each of the reference zones of interest; capturing an inspection image of a tire under inspection; and, after completion of pre-processing of the inspection image, automatically: superimposing the reference map on the inspection image, and, for each of a plurality of zones of interest of the inspection image, running the specific registration and checking algorithm for a corresponding one of the reference zones of interest, to determine a conformity of the tire under inspection.

Optimized method for analyzing the conformity of the surface of a tire

A method of rectifying an image representing a surface of a tire is provided. According to the method, a circumferential marking present on a tire is detected in an image of the tire. Based on the marking, and for each line of a plurality of lines of the image, a reference position on the tire is determined. For each of the lines of the image, a difference between the reference position on the line under analysis and a minimum value of the reference positions for all of the lines of the image is determined. For each of the lines of the image, pixels of the line under analysis are radially offset by a value of the difference.

Tire image rectifying method

To analyze a tire surface, a 3D elevational image is captured, which is formed of pixels representing points on the surface. Each point is assigned a grey-level value proportional to its elevation relative to a surface level. Based on the elevations in the elevational image, an orientational image is formed showing elevation gradients of the surface. In the orientational image, which is formed of pixels representing points on the surface, each point is assigned a grey-level value proportional to an angle formed with a direction given by a projection in an image plane of a non-zero norm vector substantially corresponding, at this point, to a gradient vector tangent to the surface and oriented in a direction of greatest slope. A filtered image is determined by transforming the orientational image using a filter to select areas that include structures similar to those in a reference orientational image of a blow hole.

Method for processing a digital image of the surface of a tyre in order to detect an anomaly

A device for rotating a tire includes a fixed support, a driving belt, a plurality of first pulleys, and at least one second pulley. The driving belt has a contact face for contacting an annular part of the tire, and the driving belt enables rotation of the tire. The first pulleys are mounted on the support and are in abutment with the driving belt on a side opposite to the contact face in order to press the contact face radially against the annular part of the tire. The at least one second pulley is in abutment with the contact face of the driving belt and is mounted for translational movement on the support in order to locally space the contact face apart from the annular part of the tire.

Rotatably driving device for the visual inspection of a tire and associated method

Acquisition device for taking a digital relief image of the surface of a tire having two color cameras for the acquisition of stereoscopic images. Each camera has N primary image sensors in a given primary color (R, G, B), where N is equal to or greater than two. Each camera is placed so as to acquire the light emitted (E) towards a predetermined area (Z) of the surface of the tire by N lights and reflected (F) by the surface of the tire. The N lights simultaneously project each independently and along the same direction onto the predetermined area of the surface of the tire. The projected light has a wavelength that corresponds to one of the primary colors of the cameras, according to a fringe system (S, S, . . . S) consisting of an alternation of illuminated and non-illuminated bands of given width (L, L, . . . L).

Evaluation of the relief of a tire surface by active stereovision

A method for inspecting a portion of a tire surface involves comparison with an image of a three-dimensional ('3D') reference surface. The method includes: extracting contours of graphic elements of an image of a 3D profile of a surface to be inspected; transforming the reference surface by establishing a correspondence between the contours of the graphic elements of the surface to be inspected and contours of identical graphic elements of the reference surface using a series of transformations; associating a B-spline surface, which includes control points, with the graphic elements of the transformed reference surface; and deforming the contours of the graphic elements of the reference surface by modifying positions of the control points of the B- spline surface so as to minimize distances between the contours of the graphic elements of the reference surface and the contours of the graphic elements of the surface to be inspected corresponding thereto.

Method for the pre-processing of a three-dimensional image of the surface of a tyre for use in the inspection of said surface

A method of determining relief markings on a tire's sidewall surface includes assigning, to each pixel of a three-dimensional image of the surface, a grey-level value proportional to an elevation point corresponding to the pixel, to obtain a starting image. Using linear structuring elements of successively increasing sizes and oriented circumferentially, a series of successive morphological openings is performed iteratively on the starting surface. An image value obtained after a morphological opening using a structuring element is subtracted from an image value obtained after a morphological opening using a structuring element of an immediately lower size, to obtain a succession of images flattened by differencing. A thresholding operation is performed on the images flattened by differencing, to obtain binary images. A set-theoretic union of values of each of the binary images is performed, to obtain a final binary image in which markings appear in relief.

Method for determining markings in relief on the outer surface of the sidewall of a tyre

A method for inspecting tire tread, having circumferentially juxtaposed elements separated by identically shaped boundaries and having patterns arranged in a predetermined sequence, includes: acquiring an image of a surface of the tire tread, the image including pixels associated with a light-intensity level; transforming the image by circumferentially offsetting pixels located axially at a same distance (x, x) from a given circumferential reference (OY), by an inverse (&#x2212;y, &#x2212;y) of a circumferential offset (y, y) with respect to an axial line (OX) of a point (P, P) located on a boundary line of known shape at the same axial distance (x, x) from the circumferential reference (OY), such that boundaries between elements appear as straight traces orientated in an axial direction; and analyzing the image to identify points located on an axially orientated straight line, the points being treated as points located on a boundary line between two elements.

Method for identifying and defining basic patterns forming the tread pattern of a tyre

A method of determining relief elements on a tire surface includes capturing a three-dimensional image of the surface and assigning to each pixel (i, j) of the image a grey-level value proportional to a topographic elevation of a point corresponding to the pixel, so as to obtain a starting image (&#x192;). The method also includes transforming the starting image (&#x192;) by a first top-hat operation, with aid of a first structuring element, so as to obtain an image (&#x192;) flattened by differencing, (&#x192;=&#x192;&#x2014;&#x3b3;(&#x192;)). The method further includes performing a thresholding operation on the image flattened by differencing, so as to obtain a segmented image, (T(&#x192;)=seg) in which relief elements appear white on a black background.

Method for determining elements in relief on the surface of a tyre

A tire tread, having circumferentially juxtaposed elements separated from one another by identically shaped boundaries and having a least one basic pattern, is inspected by: producing an image of the tire tread; identifying tread wear indicators on the image; grouping together sub-sets of the indicators according to the basic pattern(s) included in the indicators; determining a characteristic point of each of the sub-sets of the indicators; determining a sequence of distances by computing distances between the characteristics points of each of the sub-sets of the indicators; comparing and the sequence of distances with a known sequence of distances between characteristic points of the basic pattern(s) to confirm coincidence thereof; and projecting a shape of a boundary between elements of the tire tread onto a surface to be inspected according to the known sequence of distances between characteristic points of the basic pattern(s).

A device for evaluating the appearance of the surface of a tire (P) comprising a color linear camera () comprising means () for separating the light beam (F) reflected by the surface of said tire (P) and entering the camera () into at least two base colors (R, G, B) of given wavelength, so as to direct the light beam to as many sensors () capable of obtaining a basic image in gray level () for each of the base colors, as many lighting means () as base colors, said lighting means being oriented so as to light the surface to be evaluated at different angles, characterized in that each of the lighting means () emits a colored light (R, G, B) that differs from that of the other lighting means, and the wavelength of which corresponds substantially to the wavelength of one of the base colors selected by the camera.

Device for evaluating the surface of a tire

Method for inspecting a zone of the surface of a tire, said surface comprising markings in relief, wherein the three-dimensional profile of the surface to be inspected is determined, characteristic points on the surface to be inspected are located and these points are matched with the corresponding points originating from the three-dimensional data of a reference surface, so as to create a set of pairs of matched points, in an iterative manner, a first affine transformation function is sought, applied to the characteristic points of the reference surface, so that the value representing the sum of the distances between each of the characteristic points of the reference surface, which points are transformed with the aid of said first transformation function, and the points of the surface to be inspected that are matched with them, is minimal, and said first transformation function is applied to all of the points of the reference surface in order to obtain a transformed reference surface.

Method for processing a three-dimensional image of the surface of a tire so that it can be used to inspect the said surface

A method for evaluating the surfaces of a tire, said surfaces being molded with rigid elements, wherein a collection of N images of a given zone of the tire is constituted based on the images originating from one or more tires, each of the images of the collection being constituted by the values of physical magnitudes measured by a sensor sensitive to the reflection of the light at each of the points with coordinates i, j of said surface, and then the images of said collection are made to correspond by superposition, and the image of the zone of a tire from said collection to be evaluated is compared with a reference image. The value of the physical magnitudes of the reference image is calculated based on the value of each of these physical magnitudes measured on the N images of said collection.

Growing community of inventors

Clermont-Ferrand, France

Alexandre Joly