Automatic repair method for damage to a tire

Abstract

This automated repair process for damage to a tire casing containing metallic wires comprises the following steps: - Detection (step R1) of the position of at least one anomaly zone and one undamaged zone on an image of at least one wire in the casing; - Categorization (step R2) of the detected anomaly zone into two types: an anomaly zone to be brushed if gum is present in the immediate vicinity of said anomaly zone, and an anomaly zone to be ground for all other anomaly zones; - Selection (step R3) of the repair tool between a brush and a grinding wheel depending on the category of the detected anomaly zone; and - Repair (step R7) of the wire using the selected repair tool on said wire. Figure for the abbreviation: Fig. 1

Description

Title of the invention: Method for automatically repairing damage to a tire technical field

[0001] The present invention relates to the detection of damage and its repair on a tire, for example a tire adapted to equip a vehicle such as a motor vehicle, a heavy goods vehicle or an airplane.

[0002] In particular, the present invention relates to the automatic detection and repair of damage located at the level of a layer comprising metal cables of a tire carcass.

[0003] The present invention can more generally be implemented for the purpose of retreading a tire. Previous techniques

[0004] A tire, and in particular the plies or carcass of a tire, is generally repaired manually in its entirety when such a repair step is possible.

[0005] The purpose of this step is to repair the various damages sustained by the carcass during the rolling of the tire. At the beginning of this step, the tire is carded, in other words the remaining worn rubber tread has been removed using a carding machine, so as to make accessible the tire plies, which are then considered to be exposed or more precisely coated with a thin layer of rubber.

[0006] The term "tire carcass" refers to a tire whose tread has been removed, leaving a layer of metal cables exposed.

[0007] A tire web is a metallic web which includes a set of metal cables, coated with a thin layer of rubber, allowing the tire to be encircled and to guarantee its resistance.

[0008] A tire tread, for example, is subject to corrosion and rust, which attacks the various cables. One solution to remove this rust is to use a grinding wheel directly on the cables.

[0009] Another possible damage is the presence of so-called "unhealthy" cables including so-called structural anomalies, in other words cut cables, or cables that bend back, or even cables or rubber that are cracked, etc...

[0010] In order to know which areas of the tire carcass to repair, some current solutions use colorimetric analysis to identify the presence of rust.

[0011] However, no existing method allows for the identification of damage other than the presence of rust.

[0012] Furthermore, no existing method allows for the automation of the search for these other damages, the detection of damages and their repair. Description of the invention

[0013] The present invention therefore aims to overcome the aforementioned drawbacks and to provide an automatic and efficient method for repairing a tire casing.

[0014] The present invention relates to a method for the automatic repair of damage to a layer comprising metal cables of a tire casing, the method comprising the following steps:

[0015] - Detection of the position of at least one anomaly zone and one healthy zone on an image of at least one cable of the ribbon cable;

[0016] - Categorization of the detected anomaly zone according to two types of anomaly zone, an anomaly zone intended to be brushed if gum is present in the immediate vicinity of said anomaly zone, and an anomaly zone intended to be ground for any other anomaly zone;

[0017] - Choice of repair tool between a brush and a grinding wheel depending on the category of the anomaly zone detected; and

[0018] - Repair of the cable by using the repair tool selected on said cable.

[0019] Thus, this process makes it possible to automate the detection and repair of a tire casing. Furthermore, it allows for the optimization of this repair by taking into account the nature of the anomaly area in order to select the appropriate repair tool.

[0020] In one embodiment, the detection step is followed by a grouping step of several detected anomaly zones into a primary anomaly zone when said anomaly zones are located at a distance less than a predefined distance from each other.

[0021] Advantageously, the process includes, before the repair step, a step of enlarging an anomaly zone to a predefined minimum size when said anomaly zone has a size less than said predefined minimum size.

[0022] In a particular embodiment, the repair step is carried out so that the repair tool has a translational movement along the longitudinal direction of the cable from the healthy area to the anomaly area, as well as a rotational movement about an axis orthogonal to the translational movement and in the opposite direction to a rolling direction of the repair tool on said cable.

[0023] Advantageously, the method takes into account the orientation of the cables, which makes it easier to maintain and / or cut them, especially since damage, more particularly corrosion damage, usually propagates along a cable and not transversely.

[0024] Implementing a rotational movement with an axis orthogonal to the translational movement and in the opposite direction to a direction of rolling of the repair tool on said cable also allows for better maintenance and / or cutting of the cables of the tire carcass's ribbon.

[0025] Advantageously, the brush includes rigid metal bristles adapted to remove gum located on cables from the tire carcass ply, the grinding wheel being made of carbide or stone.

[0026] Advantageously, the detection step includes the detection of the position of at least one anomaly zone, preferably including a structural anomaly, by machine learning and optionally by image processing in visible, multispectral or infrared color, the image of at least one cable of the ribbon being a visible, multispectral or infrared color image.

[0027] In a particular embodiment, the method includes prior to an image acquisition step, preferably a secondary image in visible colors, multispectral or infrared, of at least one cable of the ribbon cable.

[0028] Advantageously, the method includes, after the detection step, a registration step of a primary image of the tire acquired by a main imaging system fixed relative to the tire carcass with the image, preferably the secondary image in visible colors, multispectral or infrared, acquired by a secondary imaging system mobile relative to the tire carcass and whose field of observation is included in the field of observation of the main imaging system, the registration step being implemented by applying a registration homography to said main image or to said secondary image.

[0029] The present invention also relates to an industrial repair system comprising a fixed main imaging system including one or two cameras adapted to acquire a three-dimensional point cloud, a mobile secondary imaging system, preferably with a visible, multispectral or infrared color sensor, whose field of observation is included in the field of observation of the main imaging system, an effector including a repair tool, the repair system including means for implementing the process as defined above, the effector being driven by the main imaging system to perform the repair step.

[0030] The present invention also relates to a computer program comprising instructions which, when the program is executed by a computer, lead the computer to implement the steps of the process as defined above.

[0031] The system includes, for example, a computer and a computer-readable data medium, the computer program as defined above being stored on the data medium. Brief description of the drawings

[0032] Other objects, features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example, and made with reference to the accompanying drawings in which:

[0033] [Fig.1] is a schematic representation of the different stages of the tire casing repair process according to the invention;

[0034] [Fig.2] is a schematic representation of an industrial repair system according to the invention;

[0035] [Fig.3] is a schematic representation of anomaly zones detected during the process according to [Fig.1];

[0036] [Fig.4] is a schematic representation of the anomaly zone grouping step implemented in the process according to [Fig.1];

[0037] [Fig.5] is a schematic representation of the repair step of an anomaly zone implemented in the process according to [Fig.1];

[0038] [Fig.6] is a schematic representation of the repair step of an anomaly zone implemented in the process according to [Fig.1], in the opposite direction to the direction shown in [Fig.5].

[0039] Detailed description of at least one embodiment

[0040] The different stages of an automatic repair process for damage to a tire casing according to the invention are schematically represented in [Fig.1].

[0041] The process is for example implemented by means of an industrial repair system 1 represented in [Fig.2], for example a computer 3.

[0042] The industrial repair system 1 also includes a fixed primary imaging system 5 and a mobile secondary imaging system 7. These two imaging systems 5 and 7 are adapted to image an object to be observed 9, in this case a tire 9 or more precisely a tire casing 9. This is in fact a tire from which the tread has been removed. The surface of the casing of pneumatic 9 presents a layer of metal cables coated with a thin layer of rubber material, the rubber.

[0043] The industrial repair system 1 includes a robot 11 comprising one or more arms, one of the arms being able to support the main imaging system 5 and / or the secondary imaging system 7.

[0044] The industrial repair system 1 includes an effector 13, in other words a tooling element, supported by a robot arm 11, enabling the repair of the tire casing 9 to be carried out.

[0045] The effector 13 includes at least one repair tool, for example a brush, also called a hard brush, and / or a grinding wheel.

[0046] The brush includes rigid metal bristles adapted to remove residual gum from a wired web of a tire carcass.

[0047] The grinding wheel comprises, for example, a hard material such as carbide or stone and is adapted for cutting portions of wire cables, in particular portions of cables that have been sheared and are curled back. After the grinding wheel passes over a sheet, the cables are straight and pressed against the carcass of the tire 9, their ends having been cut by beveling them to follow the curvature of said tire carcass 9.

[0048] The main imaging system 5 is said to be fixed because it is adapted to image the tire carcass 9 from a fixed point at a fixed working distance Dp from said tire carcass 9, for example between 500 and 700 mm, preferably 600 mm.

[0049] The main imaging system 5 can be a 3D imaging system comprising, for example, one or two cameras, for example of the RGB-D type, adapted to acquire a three-dimensional point cloud. Subsequently, the main image or any other image acquired by the main imaging system 5 is considered to be projected onto a plane perpendicular to the shooting direction to obtain a color image, the three-dimensional point cloud being used only for controlling the robot.

[0050] The secondary imaging system 7 is said to be mobile because it is adapted to image the tire carcass 9 from different locations, however preferably with a fixed working distance Ds, for example between 150 and 350 mm, preferably 300 mm.

[0051] The secondary imaging system 7 can be a 2D imaging system with a visible color sensor, multispectral or infrared, preferably multispectral. Indeed, for the visual inspection of tire carcasses 9, infrared, particularly near-infrared, makes it possible to highlight defects in the wiring of the cables.

[0052] The presence of rust is, for example, easily detected at wavelengths in the near-infrared.

[0053] The secondary imaging system 7 includes, for example, a 25 mm focal length lens for a sensor whose dimensions are between 10 and 15 mm in width and between 5 and 7 mm in height.

[0054] The primary imaging system 5 and the secondary imaging system 7 have a common image acquisition and / or display mode; in other words, their data can be compared to detect similar elements represented in the two images acquired by the two different systems. Preferably, the common mode is the acquisition of images in the same type of color register, for example RGB, or YCbCr or CMYK, or in grayscale.

[0055] The YCbCr and CMYK color registers are also registers used preferably by the secondary imaging system 7, as rust appears better in the image in these color registers.

[0056] Advantageously, the field of view of the secondary imaging system 7 is smaller, for example, covering an area at least 10 times smaller, and thus falls within the field of view of the primary imaging system 5. For example, the dimensions of the field of view of the secondary imaging system 7 are between 65 and 85 mm in width and between 35 and 70 mm in height. Preferably, the resolution of the secondary imaging system 3 is higher than the resolution of the primary imaging system 5.

[0057] Thus, the main imaging system 5 makes it possible to have an overview of the tire carcass 9, for example in order to guide and control the effector 13 in space for the repair of said tire carcass 9. The secondary imaging system 7 makes it possible to obtain specific information on certain areas, for example damaged areas, of the tire carcass 9.

[0058] The implementation of the automatic repair process for damage to a layer comprising metal cables of a tire carcass is particularly suitable for a worn tire which will be retreaded.

[0059] Prior to implementing the present method, a step is carried out to remove the tread, in other words, the rubber on the outer periphery of the tire, in order to subsequently apply a new tread made of one or more strips of rubber material, and then a curing step is carried out to vulcanize said rubber material. Removing the worn tread yields a tire carcass 9. The outer surface of the carcass is composed of a sheet of metal wire coated with rubber material, the rubber.

[0060] Optionally, a brushing step of the eraser is also carried out beforehand to expose the cables of the ribbon cable.

[0061] The steps of the present process are illustrated in [Fig. 1].

[0062] First, an RI step is performed to detect the position of at least one anomaly zone and a healthy zone on an image of at least one cable of the ribbon cable.

[0063] The image on which the areas of anomaly and healthy areas are detected is, for example, a secondary image acquired by the secondary imaging system 7 as described above, preferably multispectral.

[0064] In a particular embodiment, the present method includes the prior implementation of an R0 step of acquiring said image, preferably the secondary image, in visible colors, multispectral or infrared, of at least one cable of the ribbon cable.

[0065] In a particular embodiment, the IR detection step includes detecting the position of at least one anomaly zone by machine learning. This type of detection makes it possible to detect, in particular, structural anomalies, which was not possible in the prior art.

[0066] Machine learning, for example, uses a neural network and an unsupervised learning method which, starting from a first image containing an anomaly in the tire casing, can reconstruct a second image of the undamaged tire casing. By comparing the first and second images, it is easy to identify an area of ​​anomaly.

[0067] Optionally, the IR detection step is also performed by visible, multispectral, or infrared color image processing, the image of at least one cable in the ribbon cable being a visible, multispectral, or infrared color image. This processing makes it possible, in particular, to detect rust, grease (i.e., heated rubber with a greasy and / or melted appearance), or blue discoloration of the cables.

[0068] Then, optionally, a step R2 is carried out to categorize the detected anomaly zones according to at least two types of anomaly zone, for example represented on [Fig.3], an anomaly zone intended to be brushed Z1 and an anomaly zone intended to be ground Z2, a healthy zone having the reference Z0.

[0069] In particular, the anomaly zone intended to be brushed is categorized as such if gum G is present in the direct vicinity, in other words in contact, of said anomaly zone, any other anomaly zone being categorized as an anomaly zone intended to be ground.

[0070] The anomaly zones are preferably represented in the form of a rectangle whose length follows the longitudinal direction of the cables C.

[0071] Then, a step R3 is carried out to choose a repair tool between a brush and a grinding wheel, the repair step being implemented with the chosen repair tool.

[0072] Preferably, a repair of the anomaly area intended to be brushed ZI is carried out with the brush. As this area is at the edge of the rubber G, it is necessary to brush the rubber to remove it and to check that the detected anomaly has not propagated under the rubber along the cables, as is regularly the case with rust, for example.

[0073] Once an anomaly zone intended to be brushed ZI has actually been brushed during the repair step R7 described below, it can be recategorized as an anomaly zone intended to be ground Z2 if it actually corresponds to this category.

[0074] Preferably, a repair of the anomaly area intended to be ground down Z2 will be carried out with the grinding wheel. This makes it possible to cut or remove the cable in order to prevent it from bending back or simply to permanently remove the rust.

[0075] Then, optionally, a step R4 is carried out to group several detected anomaly zones, where appropriate anomaly zones of the same type, into a primary anomaly zone when said anomaly zones are located at a distance less than a predefined distance from each other.

[0076] This step R4 is represented on [Fig.4] where different anomaly zones intended to be brushed ZI are grouped into a larger anomaly zone intended to be brushed ZI.

[0077] Following the same principle, an optional R5 step is performed to enlarge an anomaly area to a predefined minimum size when said anomaly area is smaller than said predefined minimum size. The predefined minimum size depends on the dimensions of the repair tool(s) under consideration. In particular, the predefined minimum size must be greater than the pass width and the footprint length of the repair tool. For example, the width of an anomaly area is between 1 and 4 cm, this dimension being converted into pixels in the image acquired by the secondary imaging system. The length of the anomaly area is, for example, twice the width.

[0078] This allows the repair tool to move more easily over the different areas of detected anomaly and thus make the repair more efficient, without redundancy.

[0079] Optionally, and advantageously before the repair step R7, a registration step R6 is performed of a primary image of the tire acquired by the main imaging system 5 fixed relative to the tire carcass with the image, preferably the secondary image in visible colors, multispectral or infrared, acquired by the secondary imaging system 7 mobile relative to the tire carcass and whose field of observation is included in the field of observation of the main imaging system.

[0080] The R6 registration step is implemented by applying a registration homography to said main image or to said secondary image.

[0081] This R6 registration step allows for a perfect superposition of the primary and secondary images respectively acquired by the main imaging system 5 and the secondary imaging system 7, and thus to be able to precisely control the effector 13 in space thanks to the wide view of the main imaging system 5 and the precision of the information of the secondary imaging system 7.

[0082] Finally, a cable repair step R7 is carried out using the repair tool on said cable. This step R7 is illustrated schematically in [Fig.5].

[0083] Advantageously, the repair tool 15 is placed in contact with the tire casing 9 tangentially to the surface of said tire casing 9. The repair tool 15 then undergoes a translational movement M1 along the longitudinal direction of the cable C from the sound zone Z0 to the anomaly zone Z1 or Z2. This movement M1 optimizes the repair by taking into account the cable orientation, thus allowing for better maintenance and / or cutting, especially since damage generally propagates along a cable and not transversely.

[0084] Combined with the translational movement, the repair tool 15 has a rotational movement M2 about an axis orthogonal to the translational movement M1 and in the opposite direction to a rolling direction M3 of the repair tool on said cable. The direction of this movement is important and prevents the cables from bending back.

[0085] Upon reaching the center of the anomaly zone ZI or Z2, the repair tool 15 stops and is repositioned at the other end of the anomaly zone ZI or Z2 as schematically illustrated in [Fig. 6]. The repair step R7 is then carried out again in reverse order to repair the anomaly zone ZI or Z2 at each of its longitudinal ends.

[0086] The repair step R7 is carried out in particular with the grinding wheel and can thus be a grinding step.

[0087] Step R7 finally enables the automated repair of a ribbon cable of a damaged tire carcass.

[0088] Step R7 further allows the cables to be ground down and the rubber to be removed above an underlying layer of the tire carcass in order to expose the cables of said underlying layer and to allow their condition to be analyzed. If an anomaly is detected on the underlying layer, it is then possible to repeat the various steps of this repair procedure.

[0089] In general, the implementation of the steps of this process, in particular step R7 of repair with a brush or a grinding wheel, is repeated as many times as necessary on an area of ​​anomaly ZI or Z2.

Claims

Demands

1. A method for automatically repairing damage to a tire casing comprising metallic cables (9), characterized in that it comprises the following steps: - Detection (step RI) of the position of at least one anomaly zone (ZI; Z2) and a sound zone (Z0) on an image of at least one cable (C) of the tire casing; - Categorization (step R2) of the detected anomaly zone (ZI; Z2) according to two types of anomaly zone: an anomaly zone intended to be brushed (Z1) if rubber (G) is present in the immediate vicinity of said anomaly zone (Z1), and an anomaly zone intended to be ground (Z2) for any other anomaly zone; - Selection (step R3) of the repair tool (15) between a brush and a grinding wheel according to the category of the detected anomaly zone (Z1; Z2); and - Repair (step R7) of the cable (C) by using the repair tool (15) selected on said cable (C).

2. A method according to claim 1, wherein the detection step (RI) is followed by a grouping step (R4) of several detected anomaly zones (Z1; Z2) into a primary anomaly zone when said anomaly zones (Z1; Z2) are located at a distance less than a predefined distance from each other.

3. A method according to any one of claims 1 and 2, comprising, before the repair step (R7), a step (R5) of enlarging an anomaly zone (Z1; Z2) to a predefined minimum size when said anomaly zone has a size less than said predefined minimum size.

4. A method according to any one of claims 1 to 3, wherein the repair step (R7) is implemented so that the repair tool (15) has a translational movement (M1) along the longitudinal direction of the cable (C) from the sound area (Z0) to the anomaly area (Z1; Z2), as well as a rotational movement (M2) with an axis orthogonal to the translational movement and in the opposite direction to a rolling direction (M3) of the repair tool (15) on said cable (C).

5. A method according to any one of claims 1 to 4, wherein the brush comprises rigid metal bristles adapted to remove gum located on cables from the tire carcass ply, the grinding wheel being made of carbide or stone.

6. A method according to any one of claims 1 to 5, wherein the detection step (RI) comprises the detection of the position of at least one anomaly zone (ZI; Z2), preferably comprising a structural anomaly, by machine learning and optionally by visible, multispectral, or infrared color image processing, the image of at least one cable of the ribbon cable being a visible, multispectral, or infrared color image.

7. A method according to any one of claims 1 to 6, comprising prior to an image acquisition step (RO), preferably a secondary image in visible colors, multispectral or infrared, of at least one cable (C) of the ribbon cable.

8. A method according to any one of claims 1 to 7, comprising, after the detection step (RI), a registration step (R6) of a primary image of the tire acquired by a main imaging system (5) fixed relative to the tire carcass (9) with the image, preferably the secondary image in visible, multispectral or infrared colors, acquired by a secondary imaging system (7) mobile relative to the tire carcass (9) and whose field of observation is included in the field of observation of the main imaging system (5), the registration step (R7) being implemented by applying a registration homography to said main image or to said secondary image.

9. An industrial repair system (1) comprising a fixed primary imaging system (5) including one or two cameras adapted to acquire a three-dimensional point cloud, a mobile secondary imaging system (7), preferably with a visible color, multispectral, or infrared sensor, the field of view of which is contained within the field of view of the primary imaging system, an effector (13) including a repair tool (15), the repair system (1) including means (3) for carrying out the method according to any

10. of claims 1 to 8, the effector (13) being driven by the main imaging system (5) to perform the repair step (R7). A computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the steps of the process according to any one of claims 1 to 8.

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