Device and method for analysis of tyres comprising first and second image acquistion systems

Abstract

Device and method for analysis of tyres are presented. The device includes a support frame, a flange, and first/second image acquisition systems. According to one aspect, the first acquisition system is two-dimensional and includes a first camera having a first optical axis, a first focal plane, a first focal point, and a first depth of field, and a first illumination system that illuminates around the first focal point. According to another aspect, the second image acquisition system is three-dimensional and includes a second camera having a second optical axis, a second focal plane, and a second depth of field, and a second illumination system. A translation plane, substantially orthogonal to the first optical axis, is defined by the first focal point, and an intersection between the second optical axis and the second depth of field.

Claims

1. A device for analysis of tyres, comprising: i) a support frame and a flange configured to attach the support frame to a device movement member; ii) a first acquisition system configured to acquire images of a surface of a tyre, the first acquisition system being mounted on the support frame and comprising: a first camera comprising: a first optical axis; a first focal plane; and a first depth of field, and a first illumination system adapted to illuminate around a first focal point that is situated on an intersection between the first optical axis and the first focal plane; and iii) a second acquisition system configured to acquire images of the surface of the tyre, the second acquisition system being mounted on the support frame and comprising: a second camera comprising: a second optical axis; a second focal plane; and a second depth of field, and a second illumination system, wherein the first and second acquisition systems define a translation plane that is substantially orthogonal to the first optical axis, and passes through the first focal point and through a first intersection region between the second optical axis and the second depth of field.

2. The device according to claim 1, wherein: the first acquisition system is adapted to acquire two-dimensional images and the second acquisition system is adapted to acquire three-dimensional images, the second camera is a matrix camera, the second illumination system comprises a laser source adapted to emit a linear beam having a propagation plane, and the second optical axis is tilted with respect to said propagation plane.

3. The device according to claim 2, wherein the translation plane passes through a second intersection region between the propagation plane and the second depth of field.

4. The device according to claim 3, wherein the first and second acquisition systems define one or more additional translation planes, each substantially orthogonal to the first optical axis, and each passing through the first focal point, through the first intersection region, and through the second intersection region.

5. The device according to claim 1, wherein the translation plane is a plane orthogonal to the first optical axis and coincides with the first focal plane.

6. The device according to claim 2, wherein the translation plane passes through a second focal point that is situated on an intersection between the propagation plane, the second focal plane, and the second optical axis.

7. The device according to claim 1, wherein the first camera is a linear camera comprising an objective line that lies on an intersection between: the first focal plane, and an optical plane that passes through the first optical axis and a linear sensor of the linear camera.

8. The device according to claim 7, wherein the objective line and an intersection line between the translation plane and the propagation plane are parallel and aligned with respect to a translation direction orthogonal thereto and belonging to the translation plane.

9. The device according to claim 2, wherein the second camera is arranged on a side opposite the first camera with respect to the laser source.

10. The device according to claim 7, wherein: the propagation plane is parallel to the optical plane of the first camera, and the second focal plane is tilted with respect to the translation plane.

11. The device according to claim 1, further comprising an opaque separator interposed between the first illumination system and the first intersection region.

12. The device according to claim 2, wherein: the first illumination system is adapted to emit within a first optical band, the second laser source is adapted to emit within a second optical band substantially separated from the first optical band, the second acquisition system further comprises an optical filter optically arranged in front of an objective lens of the second camera, the optical filter being adapted to pass the second optical band and to substantially block the first optical band.

13. The device according to claim 1, further comprising a secondary support frame on which the first illumination system is rigidly mounted, wherein the secondary support frame is movably mounted on the support frame so that it can rectilinearly translate along a direction substantially parallel to the first optical axis, from a position close to the first camera to a position distal from the first camera, and vice versa.

14. The device according to claim 1, further comprising a secondary support frame on which the first illumination system is rigidly mounted, wherein: the first camera, the second camera, and the second illumination system are rigidly mounted on the support frame in proximity to a first end of the device, the secondary support frame is rigidly fixed to the support frame in proximity to a second end of the device longitudinally opposite the first end, and wherein a distance along the first optical axis between an external optical surface of the first camera and the first focal point is greater than or equal to 250 mm.

15. The device according to claim 7, wherein the first illumination system comprises: a first light source, a second light source, and a third light source, adapted to respectively emit a first light radiation, a second light radiation, and a third light radiation, to illuminate the objective line, wherein: the first light source and second light source respectively lie on opposite sides with respect to the optical plane and are mirrored with respect to the optical plane, the third light source is interposed between the first light source and the second light source, each of the first light source and the second light source is adapted to illuminate the objective line with a respective grazing light, and the third light source is adapted to illuminate the objective line with diffuse light.

16. The device according to claim 15 wherein: each of the first light source, the second light source, and the third light source, comprises one or more respective sub-sources, each of the one or more respective sub-sources comprises a respective main extension direction that is substantially parallel to the objective line, the third light source comprises a plurality of respective sub-sources distributed in a symmetric manner with respect to the optical plane, the first light source and the second light source each comprise only one sub-source, the sub-sources of the first light source, second light source and third light source are arranged on a plane orthogonal to the objective line and along an arc-of-a-circle having concavity directed towards the objective line, and each of the one or more respective sub-sources comprises a support body with a circular cross section and one or more elementary light sources.

17. The device according to claim 1, further comprising a secondary support frame on which the first illumination system is rigidly mounted, wherein: the first illumination system comprises one or more support bodies and one or more elementary light sources, the secondary support frame comprises a pair of lateral walls that are opposite each other and a bottom wall interposed between the lateral walls, the pair of lateral walls are fixed to the bottom wall via a thermal glue interposed in contact between each wall of the pair of lateral walls and the bottom wall, and the one or more support bodies are interposed between the pair of lateral walls and fixed thereto via a thermal glue interposed in contact between the one or more support bodies and the pair of lateral walls.

18. The device according to claim 17, wherein: the secondary support frame and the one or more support bodies are made of aluminium, and the one or more support bodies and the bottom wall are provided with respective ribbings configured to be vertically positioned during usage of the device.

19. The device according to claim 1, further comprising a drive and control unit that is mounted on the support frame, wherein the drive and control unit is adapted to turn on the first illumination system and the second illumination system, and to activate the first camera and the second camera simultaneously with a respective turning on of the first illumination system and the second illumination system.

20. A station for analysing tyres in a tyre production line, the station comprising: a support adapted to support the tyre set on a sidewall of the tyre, and to rotate the tyre around its rotation axis; the device according to claim 1; and the device movement member on which the device is mounted by means of the flange of the device.

21. The station according to claim 20, wherein the device movement member is a robotic arm comprising: a single system for detection of an angular position of the support; a drive and control unit configured to turn on the first illumination system and the second illumination system, and to activate the first camera and the second camera as a function of a single angular position signal of the support detected by the single system.

22. A method for analysing tyres, comprising: providing the device according to claim 1; translating, with respect to the device, a surface region of a tyre; based on the translating, maintaining the surface region above, or in proximity to, the translation plane of the device, at least at the first focal point of the device; activating the first acquisition system and the second acquisition system of the device; and based on the translating and the activating, simultaneously acquiring via the first and second acquisition systems of the device, respective series of images of a same series of distinct portions of the surface region.

23. The method according to claim 22, wherein the distinct portions of the surface region are linear surface portions.

Description

(1) Further features and advantages will become more apparent from the detailed description of some exemplary but non-limiting embodiments of a device and a station for analysing tyres in a tyre production line, according to the present invention. Such description will be given hereinafter with reference to the accompanying figures, provided only for illustrative and, therefore, non-limiting purposes, in which:

(2) FIG. 1 shows a partial and schematic perspective view of a device for analysing tyres according to the present invention;

(3) FIG. 2 shows a further perspective view of the device in FIG. 1 from a different view;

(4) FIG. 3 shows a top view of the device in FIG. 1;

(5) FIG. 4 shows a side view of the device in FIG. 1;

(6) FIG. 5 shows a partially exploded view of the device in FIG. 1;

(7) FIG. 6 shows a partially exploded view of a detail in FIG. 5;

(8) FIG. 7 shows a perspective view of the device in FIG. 1 in a retracted configuration;

(9) FIGS. 8A and 8B schematically show two possible optical configurations of the second acquisition system according to the present invention, respectively;

(10) FIGS. 9-12 show a partial and schematic view of a further embodiment of a device according to the present invention, in a perspective view from two views, in a top view and partially exploded view, respectively;

(11) FIG. 13 shows a schematic and partial view of a station for analysing tyres according to the present invention.

(12) With reference to FIG. 13, reference numeral 100 indicates a station for analysing tyres in a tyre production line.

(13) Preferably, the station comprises a support 120 (for example a fifth wheel) adapted to support tyre 101 set on a sidewall and to rotate the tyre around a rotation axis 140 thereof (preferably arranged vertically).

(14) Station 100 comprises a device 1 for analysing tyres.

(15) Preferably, the station comprises a movement member 102 (only shown schematically) on which device 1 is mounted for the movement thereof in space. Preferably, the movement member of the device is a robot arm, more preferably an anthropomorphic robot arm, even more preferably an anthropomorphic robot arm with at least five axes. It is noted that advantageously, device 1 is inserted within the tyre from the top and not from the bottom through support 120.

(16) Device 1 comprises a support frame 2 and a flange 3 for attaching the support frame to the device movement member.

(17) Preferably, the device comprises a first acquisition system 4 of images, preferably two-dimensional, of a tyre surface mounted on the support frame. The first acquisition system 4 typically comprises a first camera 5, having a first optical axis 6, a first focal plane 7 and a first depth of field (FIG. 3 exemplarily shows the end planes 7a, 7b of the first depth of field). Typically, the first camera has a first machine body 8 (housing the sensor and the electronics) and a first objective 9 (housing the lenses).

(18) The first acquisition system 4 typically comprises a first illumination system 10 adapted to illuminate around a first focal point F1 which is situated on an intersection between the first optical axis and the first focal plane.

(19) Preferably, the device comprises a second acquisition system 11 of images, preferably three-dimensional images of the surface mounted, preferably rigidly, on the support frame.

(20) The second image acquisition system 11 comprises a second camera 12 (typically consisting of a respective second machine body 14 and second objective 15) and a second illumination system 13.

(21) Preferably, the second camera is a matrix camera and is characterised by a second optical axis 16, a second focal plane 17 and a second depth of field (FIGS. 8A and 8B show the end planes 18, 19 of the second depth of field).

(22) Preferably, the second illumination system 13 comprises a laser source 20 adapted to emit a linear beam having a propagation plane 21, where the second optical axis 16 is tilted with respect to the propagation plane.

(23) Preferably, there is at least one translation plane 22 passing through the first focal point F1 and forming an angle of between 90+15 and 9015 with the first optical axis and also passing through a first intersection region 23a between said second optical axis 16 and the second depth of field. It is noted that the first intersection region 23a is a rectilinear segment.

(24) Preferably, said translation plane 22 also passes through a second intersection region 23b between the propagation plane 21 and the second depth of field. It is noted that the second intersection region 23b is a flat surface.

(25) For the purposes of clarity, the figures show a translation plane 22 exactly orthogonal to the first optical axis, but it may be any plane of the bundle of planes passing through the first focal point F1 and substantially orthogonal to the first optical axis which also pass through the first intersection region 23a and preferably the second intersection region 23b.

(26) In the figures, moreover, the translation plane 22 considered coincides with the first focal plane 7, but the present invention also covers embodiments (not shown) in which the first focal plane is tilted with respect to the plane orthogonal to the optical axis (for example by means of devices of the type shown in FIG. 8B with reference to the second acquisition system).

(27) Preferably, the translation plane 22 passes through a second focal point F2 which is situated on an intersection between the propagation plane 21, the second focal plane 17 and the second optical axis.

(28) Preferably, the first camera is linear and is characterised by an objective line 25 lying on the intersection between the first focal plane and an optical plane 26 passing through the first optical axis and the linear sensor of the linear camera. Exemplarily, the objective line is about 100 mm in length.

(29) Preferably, the objective line 25 and an intersection line 27 between the translation plane 22 and the propagation plane 21 are parallel to each other and substantially aligned with respect to a translation direction 28 orthogonal thereto and belonging to the translation plane (see for example FIG. 1).

(30) Preferably (as exemplarily shown in the figures), the second camera 12 is arranged on the side opposite the first camera 5 with respect to the laser source 13.

(31) FIGS. 8A and 8B schematically show a top view of the second acquisition system 11 in two respective embodiments of the present invention.

(32) In both figures, the second optical axis 16 forms an acute angle 24 with the propagation plane exemplarily equal to 15.

(33) Exemplarily, distance L2 along the second optical axis between an outer optical surface of the second camera and the second focal point is equal to 210 mm and distance L3 along the propagation axis between an outer optical surface of the laser source and the second focal point is equal to 285 mm.

(34) In FIG. 8A, the second optical axis is, as typically happens, orthogonal to the image plane 29 of the sensor. In this situation, the focal plane 17 is also orthogonal to the second optical axis, as are the extreme planes 18 and 19 of the depth of field. Assuming that the maximum altimetric excursion to be detected on the tyre surface is equal to h (for example of the order of a few tens of mm), since the tyre surface (more precisely a plane thereof at a given height) being analysed lies substantially on the translation plane 22, it follows that the length d of the depth of field should be such as to at least include such an excursion h on the propagation plane 21.

(35) As mentioned above, the term lying in the proximity of the translation plane means that the local lying plane of the surface (defined as any plane passing through a given height of the tyre surface, preferably the plane passing through the intermediate height of the maximum height excursion of the surface) at said first optical axis remains within said first depth of field (said lying plane being coinciding with said at least one translation plane when the lying plane of the surface passes through the first focal point).

(36) In the configuration in FIG. 8, where the propagation plane 21 is orthogonal to the translation plane 22 (and parallel to the optical axis of the first camera) and where the second optical axis is tilted with respect to the normal to the translation plane, the second focal plane 17 is tilted with respect to the translation plane 22. In this situation, the length d of the depth of field along the second optical axis must be greater than or equal to d.sub.min=h*cos , where is the width of the acute angle 24. Therefore, such a minimum length d.sub.min is less than a comparative configuration in which the second focal plane lies parallel to the translation plane 22, where d.sub.min=h.

(37) Preferably, as shown in FIG. 8B, the image plane 29 of the camera sensor forms, with a reference plane 30 orthogonal to the second optical axis and passing by the second objective 15, an acute angle 31 with vertex on the side where the laser source is, and exemplarily equal to 10.

(38) In this way, the second focal plane 17 forms an almost null acute angle with the propagation plane 21, and the second depth of field, in the region of interest around the translation plane 22 develops around the propagation plane 21, allowing easy focusing of the reflected laser line along excursion h, even with open aperture.

(39) Preferably, the device comprises an opaque separator 50 (only schematically shown in FIG. 3) interposed between the first illumination system 10 and the first intersection region 23a. For example, the separator may be fixed to the secondary support frame 40. The opaque separator may be of rigid material (kept, in use, slightly distant from the tyre surface), or flexible material, such as a hair brush which in use slide on the surface.

(40) Preferably, the device comprises a secondary support frame 40 on which the first illumination system is rigidly mounted.

(41) In one embodiment, such as that exemplary shown in FIGS. 1-7, the secondary support frame is movably mounted on the support frame as to translate rectilinearly, preferably along a direction parallel to the first optical axis 6, from a position proximal to the first camera (as shown in FIG. 7) to a position distal from the first camera (FIGS. 1-4). Exemplarily, the device comprises a linear actuator 42 (e.g. pneumatic) rigidly mounted on the main support frame 2 and able to move rectilinearly one or more pistons at the distal end of which the secondary support frame is fixed.

(42) In one embodiment, such as that exemplarily shown in FIGS. 9-12, the first and second camera and the laser source are rigidly mounted on the support frame in the proximity of a first end 43 of the device, and the first illumination system is rigidly mounted on the secondary support frame 40 in turn rigidly fixed to the support frame 2 in the proximity of a second end 44 longitudinally opposite the first end 43.

(43) Exemplarily, distance L1 along the first optical axis between an outer optical surface of the first camera and the first focal point is equal to 320 mm and objective 9 of the first camera has a focal length of 50 mm.

(44) By comparison, in the embodiment shown in FIGS. 1-4, such a distance L1, in the extracted configuration, is exemplarily equal to 220 mm and the objective used has a focal length of 35 mm.

(45) Preferably, the first illumination system includes a first light source 51, a second light source 52 and a third light source 53 adapted to emit a first, a second and a third light radiation, respectively, to illuminate said around the first focal point (e.g. the objective line 25).

(46) Preferably, the first light source 51 and the second light source 52 lie respectively on opposite sides and mirror-wise with respect to the optical plane 26 and the third light source 53 is interposed between the first and second source.

(47) Preferably, each of the first and second light source is adapted to illuminate the objective line with a respective grazing light, and the third light source is adapted to illuminate the objective line 25 with diffuse light.

(48) Preferably, each of the first light source, second light source and third light source comprises one or more respective sub-sources 54, each having a respective prevailing development direction 55 substantially parallel to the objective line.

(49) Preferably, the third light source 53 comprises a plurality, such as four, of respective sub-sources 54 distributed symmetrically with respect to the optical plane.

(50) Preferably, the first light source and the second light source comprise each a single sub-source 54.

(51) Preferably, the respective sub-sources are structurally and/or dimensionally equal to each other.

(52) Preferably, the respective sub-sources have a rectilinear development along the prevailing development direction 55.

(53) Preferably, the sub-sources of the first, second and third light source are arranged on a line 56 on a plane orthogonal to the objective line, with concave side facing toward the objective line, exemplarily as an arc of a circle.

(54) Preferably, all the sub-sources lying on one side of the optical plane are distributed mutually equally spaced.

(55) Preferably, each sub-source 54 comprises a support body and one or, typically, more elementary light sources (e.g. LED type), not shown, housed in a cavity 60. Preferably, the support bodies have a circular cross section. In the figure, the support bodies are only schematically shown, it being understood that the front part of the support bodies is transparent and typically consists of a glass (e.g. diffuser) separate from the remainder of the support body. Such a glass front part has a LED protection function from external agents and acts as a lens adapted to concentrate the lighting rays emitted by the led itself, preventing the dispersion of light useful for the acquisition of images.

(56) Preferably, the secondary support frame 40 consists of a pair of opposite side walls 57 and a bottom wall 58 interposed between the side walls, the side walls being fixed to the bottom wall, where a thermal glue is interposed in contact between each side wall and the bottom wall.

(57) Preferably, the support bodies are interposed between the side walls 57 and fixed to the latter, where a thermal glue is interposed in contact between the ends of the support bodies and the side walls 57.

(58) Preferably, the said support bodies and/or the bottom wall 58 are provided with a respective ribbing 59, arranged in a manner such to be vertically situated during use.

(59) Preferably, the device comprises a drive and control unit 70 for the first and second acquisition system rigidly mounted on the support frame, the drive and control unit being programmed to turn on the first and second illumination system and activate the first and second camera simultaneously with the turning on of the respective lighting systems.

(60) It is noted that in the figures, the power and/or control and/or communication cables are shown only in part.

(61) Preferably, the drive and control unit is configured for:

(62) activating, in alternating sequence, the first light source, second light source and third light source; and

(63) driving the first camera for respectively acquiring a first, second and third image synchronously with the activation of the first light source, second light source and third light source, respectively.