Vehicle inspection system and method for inspecting a sidewall of a tire in such a system

Abstract

A vehicle inspection system for obtaining information from a sidewall of a tire (11) of a moving vehicle (10) having wheels rotating around a wheel axis (W) for moving the vehicle in a moving direction, wherein the vehicle inspection system (1) comprises at least one camera (2) and an image processing machine (8), wherein the at least one camera (2) is configured to capture a plurality of images of a bottom part (12) of the tire sidewall while the vehicle (10) is moving in the moving direction, wherein the image processing machine (8) is configured to assemble only the images of the bottom part (12) of the tire sidewall to obtain the information thereof.

Description

[0001] VEHICLE INSPECTION SYSTEM AND METHOD FOR INSPECTING A

[0002] SIDEWALL OF A TIRE IN SUCH A SYSTEM

[0003] TECHNICAL FIELD

[0004] The present invention relates to a vehicle inspection system for obtaining information from a sidewall of a tire of a moving vehicle. The present invention also relates to a method for inspecting a sidewall of a tire of a moving vehicle with such a vehicle inspection system.

[0005] BACKGROUND

[0006] Vehicle inspection systems are used to acquire information on the wheel assemblies of a moving vehicle passing through the system. The information typically lies in markings on the tires. Cameras are used to take images of the wheel assemblies, after which the images are processed and sent to a database for further identification. Examples of prior art can be found for instance in US11614380B2 and US10313574B2.

[0007] There are several problems associated with prior art. One problem with some prior art vehicle inspection systems is that they are expensive and / or complex. Other prior art systems can be unreliable. Hence, there is a need to provide an improved vehicle inspection system for obtaining information from a sidewall of a tire of a moving vehicle.

[0008] SUMMARY

[0009] An object of the present invention is to solve or at least mitigate the problems related to prior art and provide a reliable and cost-efficient vehicle inspection system for obtaining information from a sidewall of a tire of a moving vehicle. This object is achieved by means of the technique set forth in the appended independent claims; preferred embodiments being defined in the related dependent claims.

[0010] According to a first aspect, a vehicle inspection system for obtaining information from a sidewall of a tire of a moving vehicle is provided. The moving vehicle has wheels rotating around a wheel axis for moving the vehicle in a moving direction. The vehicle inspection system comprises at least one camera and an image processing machine, where the at least one camera is configured to capture a plurality of images of a bottom part of the sidewall of the tire while the vehicle is moving in the moving direction. The image processing machine is configured to assemble only the images or only a part of the images of the bottom part of the tire sidewall to obtain the information of the tire sidewall. Assembling only the images of the bottom part or only the part of the images of the bottom part of the tire sidewall instead of capturing and processing images of the entire sidewall results in that a less advanced and less expensive camera or a plurality of less advanced and less expensive cameras can be used. By photographing only the bottom part of the tire sidewall and putting the photographs together instead of photographing the whole tire sidewall in one or more photographs, the need for one or more advanced and expensive cameras is reduced. For example, images are taken of only the bottom part of the tire sidewall. The images of only the bottom part of the tire sidewall are then assembled by the image processing machine to extract information from the whole tire sidewall. Alternatively, the tire sidewall or a part of the tire sidewall including the bottom part thereof is photographed but only the parts of the images of the bottom part of the tire sidewall are assembled to extract the information from the entire tire sidewall.

[0011] The tire sidewall is ring-shaped and extends 360°. Each of the images or parts thereof taken by the camera and / or processed by the image processing machine can correspond to 140°or less of the tire sidewall, such as 120°, 90°, 45°, 20° or even less. The image processing machine can be configured to assemble said images or parts of said images to obtain the information from 360° of the tire sidewall. For example, the image processing machine can extract information from only a portion of the tire sidewall around its lowermost part. Said lowermost part can have a width of 300 mm, 200 mm, 100 mm, 50 mm or less.

[0012] For example, images are captured and / or assembled of only a circular segment or only a sector of the bottom part of the tire sidewall, wherein the images are assembled to represent the information around the whole tire. Said circular segment or sector may have a central angle of 140°, 120°, 90°, 45° or less. The midpoint of the central angle may be at the lowermost part of the tire sidewall, generally the part of the tire sidewall closest to ground, which generally is corresponding to 6 o’clock using a clock analogy or along a vertical axis. By taking a plurality of images or parts of images of only the lower part of the tire sidewall while the vehicle is moving and putting the images together, information around the entire sidewall can be obtained in an efficient manner by less advanced cameras while providing sufficiently clear images or parts thereof for image processing. It has been found that images or the part of the images of the lower part of the tire sidewall of the moving vehicle is less blurry than at remaining parts of the tire sidewall, such as the upper part thereof. Analogous with a clock, it has been found that images of the tire sidewall of the moving vehicle is more clear and easily readable by the image processing machine at 5 to 7 o’clock or 4 to 8 o’clock than between 7 and 5 or 8 and 4 o’clock. It is believed that the movement of the vehicle in the moving direction compensates for the rotational speed and direction of the wheel at the lower part of the wheel. The vehicle is moving in a first direction while the lower part of the wheel is rotating generally in a second direction opposite to the first direction. For example, the camera can capture and / or the image processing machine can extract information from only a portion of the tire sidewall around its lowermost part corresponding to 4 to 8 o’clock or 5 to 7 o’clock or less.

[0013] Optionally, the vehicle inspection system further comprises at least one light source configured to illuminate the bottom part of the tire sidewall. Illumination facilitates processing of the images captured of the bottom part of the tire sidewall. A contrast effect or shadow effect can also be created by the light source, which may further facilitate for the image processing machine to process the information captured by the camera.

[0014] Preferably, the light source is non-aligned with respect to the camera. The non- alignment, or inclination of the camera and light source with respect to each other further contributes to the contrast effect or the shadow effect, which makes the captured information even more easy to process by the image processing machine.

[0015] In an embodiment, the vehicle inspection system further comprises a plurality of cameras and a longitudinal axis, e.g. extending substantially parallel to the moving direction of the moving vehicle. The cameras can be arranged along the longitudinal axis. The cameras can be arranged to take a series of images of only the lower part of the tire sidewall as the vehicle moves by the vehicle inspection system. This provides an efficient image capturing of the information around the entire tire sidewall, e.g. by means of inexpensive cameras, with only images taken of the lower part of the tire sidewall. Alternatively, the cameras can be arranged to take a series of images of the whole tire sidewall or a part of the tire sidewall including the bottom part thereof as the vehicle moves by the vehicle inspection system, wherein only the part of images showing only the bottom part of the tire sidewall are assembled. The cameras can be arranged in a first set of cameras and a second set of cameras, wherein the second set is spaced apart from and faces the first set, so that the vehicle can pass by between the first and second sets and the tires on both sides of the vehicle can be inspected simultaneously or at least in a single pass by the vehicle.

[0016] The light source can be arranged above the camera. For example, the light source and the camera are arranged along a vertical axis, optionally extending perpendicularly to the longitudinal axis. This can further contribute to the contrast effect or the shadow effect for even more efficient reading and processing of the information of the tire sidewall. A single camera and a single light source can form a set and the system can comprise a plurality of such sets distributed along the longitudinal axis. A set comprising one camera and one light source is also referred to as an image capturing assembly.

[0017] In an embodiment, the vehicle inspection system comprises at least two cameras or at least three cameras. Having a plurality of cameras is advantageous also for obtaining information from relatively large diameter wheels, such as wheels with a diameter of 500 mm and bigger, such as 700 mm or 900 mm. A plurality of cameras distributed along the longitudinal axis results in efficient obtaining of information also from of relatively large diameter wheels. The plurality of cameras makes it possible to take images of only the lower part of the tire sidewalls also of a relatively large diameter wheel and still provide images of the information from around the entire tire sidewall. Hence, where the vehicle inspection system has at least two cameras, the cameras can be spaced apart along the longitudinal axis, which provides a relatively large coverage area to capture images from.

[0018] In another embodiment, the vehicle inspection system further comprises an elongated side bar extending along the longitudinal axis. The cameras are arranged along the elongated side bar. The side bar contributes to the stability and reproducibility of the image capturing.

[0019] In a further embodiment, the vehicle inspection system further comprises a vertically extending fixture arranged on the elongated side bar. Preferably, the at least one camera is mounted to the fixture.

[0020] In another embodiment, the camera or one or more of the cameras is arranged at a camera angle, e.g. with respect to a horizontal axis, and the light source is arranged at a light source angle, e.g. with respect to a horizontal axis. For example, the camera angle and the light source angle are angles in a vertical plane in relation to the horizontal axis. The horizontal axis may substantially be aligned with or parallel with the wheel axis. The camera can be arranged at the same angle as the light source, wherein the camera and light source can be arranged in parallel. Alternatively, the camera and / or light source is / are inclined in relation to each other and / or the horizontal axis.

[0021] In an embodiment, the camera angle is different from the light source angle. This is beneficial in that the contrast or shadow effect can be created or enhanced on markings of the tire sidewall that are to be perceived by the camera.

[0022] In a further embodiment, the camera angle is either 0° or about 20°-60°, more preferably about 30°-50°, and most preferred 45°, and the light source angle is either 0° or about 20°-60°, more preferably about 30°-50°, and most preferred 45°.

[0023] In yet an embodiment, when the camera angle is 0°, the light source angle is about 20°-60°, more preferably about 30°-50°, and most preferred 45°. This is in line with the camera being inclined with respect to the light source and vice versa.

[0024] In yet an embodiment, when the light source angle is 0°, the camera angle is about 20°-60°, more preferably about 30°-50°, and most preferred 45°. This is also in line with the camera being inclined with respect to the light source and vice versa.

[0025] According to a second aspect, a method for inspecting a sidewall of a tire of a moving vehicle with a vehicle inspection system according to the above comprises the steps of: rolling the vehicle into the vehicle inspection system; capturing a plurality of images of the bottom part of the tire sidewall; sending the captured images to the image processing machine; and by means of the image processing machine assembling only the images of only the bottom part of the tire sidewall or assembling only the part of the images of only the bottom part of the tire sidewall to obtain the information of the tire sidewall.

[0026] The method and system is further beneficial in that a longer exposure time may be used by the camera and / or that relatively less illumination is needed as compared to prior art examples. Less illumination may also improve the working conditions for operators working in the vehicle inspection facility.

[0027] The method may further include the step of capturing images of the bottom part of the tire sidewall by means of a plurality of spaced apart cameras. Optionally, said images are captured in sequence as the vehicle passes the cameras. The sequence of images, or the parts thereof, can be assembled, optionally in the order they were captured, to obtain the information from the tire sidewall, wherein optionally a linear tire sidewall information output can be obtained corresponding to 360 degrees of the tire sidewall.

[0028] BRIEF DESCRIPTION OF THE DRAWINGS

[0029] By way of example, embodiments of the present invention will now be described with reference to the accompanying drawings, in which:

[0030] Fig. l is a schematic view of a vehicle inspection system in relation to a moving vehicle, wherein the vehicle is illustrated in side view and the vehicle inspection system is illustrated from above,

[0031] Fig. 2 is a perspective view of the vehicle inspection system and vehicle of Fig. 1,

[0032] Fig. 3 is a front view of the vehicle inspection system according to an embodiment,

[0033] Fig. 4 is a front view of the vehicle inspection system according to another embodiment,

[0034] Fig. 5 is a front view of the vehicle inspection system according to yet another embodiment, Fig. 6 is a side view of a rotating wheel,

[0035] Fig. 7 is a top view of the vehicle inspection system according to one embodiment,

[0036] Fig. 8 is a top view of the vehicle inspection system according to one alternative embodiment and

[0037] Fig. 9 is a schematic view of a method for inspecting a tire with the vehicle inspection system.

[0038] DETAILED DESCRIPTION OF EMBODIMENTS

[0039] With reference to Figs 1 and 2, a vehicle inspection system 1 is shown in relation to a moving vehicle 10. The vehicle 10 moves along a longitudinal axis LA of the vehicle inspection system 1, which corresponds to the moving direction of the vehicle 10 driving through the vehicle inspection system 1. This is illustrated by an arrow LA in Fig. 1. The moving direction may also be referred to as the trajectory of the vehicle 10. For example, the moving direction is substantially horizontal. For example, the vehicle inspection system is configured for receiving a vehicle moving in about 5-10 km / h. Hence, the vehicle may move through the vehicle inspection system 1 in about 5- 10 km / h, such as about 8 km / h. The vehicle has wheels rotating around a wheel axis W, and wheels with tires 11 that contain information regarding the tire’s brand, size, DOT / DOM serial number, etc., which is printed or imprinted on the tires 11. For instance, the information may protrude from the surface of the tire 11, i.e. from the sidewall of the tire 11. The information or imprints may also be referred to as markings 14 (see Figs 3-5) that may protrude from the sidewall of the tire 11.

[0040] The purpose of the vehicle inspection system 1 is to obtain information from the sidewall of the tires 11 of the moving vehicle 10 for various purposes, such as in order to propose a new tire when time is due for a tire replacement. To achieve this, the vehicle inspection system 1 includes at least one camera 2 and at least one image processing machine 8. The at least one camera 2 is configured to take a plurality of images, such as film, of a bottom part 12 of the sidewall of the tire 11, send the images to the image processing machine 8 which is in turn configured to assemble the images of the bottom part of the tire into a strip of information that can be analyzed by the image processing machine 8. Optionally, the vehicle inspection system 1 may be used as part of a process of identifying tire wear and / or damages.

[0041] In Fig. 1, three cameras 2 are shown, even though it should be understood that there may be only one camera, two cameras, four cameras etc. The cameras 2 of Fig. 1 are connected to the image processing machine 8. Furthermore, the cameras 2 are arranged along the longitudinal axis LA. The cameras 2 are spaced apart and distributed along the longitudinal axis LA. The image processing machine 8 is, for example external to the cameras 2. Moreover, the cameras 2 are configured to capture the plurality of images of the bottom part 12 of the tire sidewall while the vehicle 10 is moving in the moving direction LA. For example, the cameras 2 are configured to only capture images of the bottom part 12 of the tire sidewalls. The image processing machine 8 is configured to assemble only the images of the bottom part 12 of the tire sidewall to obtain information thereof. For example, the image processing machine 8 is configured to process the images of the bottom part of the tire sidewalls captured by the cameras 8. In the case the cameras 2 are capturing images of more than the bottom part of the tire sidewalls, the image processing machine 8 assembles only the part of the images showing the bottom parts. This is as opposed to prior art examples where images of the whole tire sidewall are captured and analyzed.

[0042] For example, the camera 2 only captures images of a circular segment or sector of the bottom part 12 of the tire sidewall. The image processing machine 8 then assembles the images to represent the information around the whole tire 11. For instance, the circular segment or sector may have a central angle of 140 degrees or 120 degrees or less with respect to the wheel axis W. Using clock bearing from the centre of the wheel the camera 2 only captures images from and / or the image processing machine 8 only assembles parts of images between 3 o’clock and 9 o’clock, such as from 4 o’clock to 8 o’clock or less.

[0043] Furthermore, the vehicle inspection system 1 includes a light source 3 configured to illuminate at least the bottom part 12 of the tire sidewall. Preferably, and as shown in relation to Figs 3 and 5, the light source 3 is non-aligned with respect to the camera 2. Together, one camera 2 and one light source 3 may be referred to as an image capturing assembly 2, 3. In Fig. 1, three image capturing assemblies 2, 3 are shown. Each image capturing assembly 2, 3 includes a camera 2 for facing the vehicle 10, and particularly a bottom part 12 of the sidewall of the tire 11, as well as a light source 3 to illuminate the bottom part 12 of the sidewall of the tire 11. According to one embodiment, the system comprises a plurality of cameras 2, e.g. arranged in parallel. For example, the system comprises a plurality of image capturing assemblies 2, 3, e.g. arranged in parallel.

[0044] The camera 2 and the light source 3 are each arranged at an angle with respect to the wheel axis W, such as a horizontal axis. Preferably, the camera 2 and the light source 3 are inclined with respect to each other, i.e. non-aligned. The position and / or inclination of the light source 3 may give rise to a contrast effect and / or a shadow effect on the tire, which makes the markings thereon easily perceptible by the camera 2 and facilitates processing of the images for obtaining the information on the tire sidewall.

[0045] The camera 2 and the light source 3 may be non-aligned in a way that they are inclined with respect to each other. Optionally, the camera 2 and light source 3 are arranged parallel to each other along a vertical axis V. The non-alignment of the camera 2 and light source 3 may contribute to the contrast or shadow effect.

[0046] The fact that the camera 2 captures images of the bottom part 12 of the tire sidewall is advantageous since a rolling shutter camera can be used and directed only towards the bottom part 12 of the tire sidewall as opposed to the whole tire sidewall. The sidewall of the tire is the side of the tire 11 between the tread shoulder and the tire bead. The tire sidewall extends substantially in a radial direction in relation to the wheel axis.

[0047] Furthermore, the bottom part 12 of the tire sidewall may be described as the area of the tire 11 that has an upper limit level with the center of the wheel, at the wheel axis W, and that extends radially downwards towards the interface between the tire and the floor, or platform. The interface between the tire and floor / platform then represents the lower limit of the bottom part 12. Alternatively, the bottom part 12 of the tire sidewall has an upper limit at a circle chord, such as a horizontal circle chord, arranged below the center of the wheel, such as in the middle between the center of the wheel and the tread shoulder or below. The tire 11 includes markings 14 on its outer surface, i.e. on its sidewall, to be read by the image processing machine 8 as described above. In Fig. 1, the bottom area 12 of the tire sidewall is illustrated schematically in dark color.

[0048] Since the vehicle 10 has a forward motion in the moving direction LA and the tire 11 rotates, the rotation of the wheel at the bottom part 12 of the tire sidewall will generally be directed in an opposite direction from the moving direction of the vehicle 10. As a result, the velocity will compensate for the rotational speed and give a more clear image of the bottom part 12 of the tire sidewall. This enables the use of a longer exposure time of the camera 2, which requires less illumination to take a photo that will be clear even indoors wherein rolling shutter cameras can be used.

[0049] As opposed to some prior art cameras that take photographs with an exposure time of less than 1 ms, the cameras 2 of the present disclosure can make use of an exposure time that is up to several milliseconds long, such as up to 2.0 ms, 2.5 ms or possibly 3.0 ms. Thus, relatively simple cameras, such as rolling shut cameras or possibly other inexpensive cameras, can be used, which provides a less expensive solution compared to prior art examples that take photographs of the whole tire.

[0050] For example, the camera 2 is a commercially available wide angle camera, and optionally includes a sensor of the area scan type, such as a rolling shutter camera. Another suitable area scan sensor is a global shutter camera. Preferably, the sensor is a passive sensor. An active sensor, such as a laser, may be feasible as well. However, a monochrome passive sensor camera 2 is preferable since it gives an output in the form of a monochrome pixel data image that is sent to the image processing machine 8, for instance an artificial (Al) intelligence system that can easily analyze the image.

[0051] As shown in Fig. 1, the image processing machine 8 is external to the camera 2. Preferably, the image processing machine 8 has different control functions for analyzing brand, size, DOT / DOM serial number, etc. of the tire 11. For example, by analyzing the DOT / DOM serial number, it can be concluded when the tire 11 was manufactured and thereby determine the expiry date of the tire 11.

[0052] As mentioned, the light source 3 of the image capturing assembly 2, 3 is configured to illuminate the bottom part 12 of the tire sidewall. Since the camera 2 may use relatively long exposure times, the light source 3 can be rather simple. This is advantageous in that the workers at the indoor facility can work safely without risk of damaging their vision. The illuminated area 13 of the tire 11 is marked in dotted lines in Fig. 1. Illumination of the bottom part 12 of the tire 11 occurs as a result of a light beam 4 that is projected onto the tire 11. Moreover, the light beam 4 from adjacent light sources may overlap slightly, or at least spread light in a way that the bottom part 12 of the tire sidewall is illuminated to create a shadow effect above or on the sides of the markings on the tire sidewall. Hereinafter, the bottom part 12 of the tire sidewall will be referred to as the bottom part 12 of the tire 11.

[0053] In Figs 1 and 2, the cameras 2 are spaced apart along the longitudinal axis LA. Similarly, the light sources 3 are spaced apart along the longitudinal axis LA. Moreover, the vehicle inspection system 1 includes an elongated side bar 5 extending parallel to the moving direction of the vehicle 10, along the longitudinal axis LA. The cameras 2 are arranged along the side bar 5.

[0054] In fact, in Figs 1-2, each image capturing assembly 2, 3 is arranged on the elongated side bar 5 and is configured to capture an image of the bottom part 12 of the tire 11 at different positions of the rolling tire 11 throughout the vehicle inspection system 1, and in particular along the length of the side bar 5. Together, the cameras 2 are spaced apart along the side bar 5, preferably substantially equidistantly. The image capturing assemblies 2, 3 may be mounted to the side bar 5.

[0055] The three image capturing assemblies 2, 3 in Fig. 2 are arranged at a distance DI from each other. The distance DI is approximately 0.8 m - 1.2 m, such as 1 m. Put differently, the image capturing assemblies 2, 3 are arranged at a distance DI from neighboring image capturing assemblies 2, 3 along the side bar 5. The distance DI is measured along or parallel to the longitudinal axis LA of the vehicle inspection system 1. In Fig. 2, the longitudinal axis LA is illustrated as extending along the length of the vehicle 10, and substantially parallel to the side bar 5. Put differently, the side bar 5 is configured to extend parallel to the trajectory of the vehicle 10, along the longitudinal axis LA. Hence, the vehicle is moving, e.g. driven, substantially in parallel to the side bar 5.

[0056] As a non-limiting example, if the side bar 5 is approximately 3 m long, with three cameras 2 mounted thereon, the image capturing assemblies 2, 3 may register an image of a wheel having a diameter of up to 900 mm. However, if the side bar 5 is approximately 2 m long, with two cameras 2 mounted thereon, a wheel diameter of up to 700 mm may be captured.

[0057] Furthermore, Fig. 2 illustrates the wheel axis W of the vehicle 10. The wheel axis W extends along a wheel axle of the wheel and is intended to be substantially perpendicular to the longitudinal axis LA. The wheel axis W may also be described as extending transversely with respect to the longitudinal extension or moving direction of the vehicle 10. An optional platform 7 is also illustrated by dotted lines in Fig. 2. The vehicle 10 may either run on the floor or on the platform 7.

[0058] In Figs 1 and 2, the light beams 4 are illustrated as having a two-dimensional cone shape extending from each image capturing assembly 2, 3 towards the moving vehicle 10. However, it should be understood that the light beams 4 are beams of scattered light rays that scatter in more than one direction. The camera 2 and the light source 3 may each be directed straight towards the tire 11 or be inclined with respect to each other in each image capturing assembly 2, 3. Furthermore, each light beam 4 is directed towards the bottom part 12 of the tire 11 by the light source 3. The light beam 4 cone preferably illuminates the tire 11 over an illumination area 13 that can be described as having a length of about 1 m as measured along the longitudinal axis LA.

[0059] Referring now to Fig. 3, the vehicle inspection system 1 is shown from a front view, with the tire 11, which bottom part 12 is to be inspected by the image capturing assemblies 2, 3 arranged along the side bar 5. Fig. 3 only shows one image capturing assembly 2, 3. However, it is understood that other image capturing assemblies described in relation to Figs 1 and 2 may be arranged similarly throughout the side bar 5.

[0060] The vehicle inspection system 1 has a vertical axis V as shown in Figs 3 and 4. The vertical axis V extends perpendicularly to the longitudinal axis LA. Furthermore, the vertical axis V extends perpendicularly to the wheel axis W. The camera 2 is arranged along the vertical axis V. In both Figs 3 and 4, the camera 2 is arranged above the light source 3. This is beneficial in that light rays L1-L5 of the light beam 4 can be reflected in the floor / platform 7 and up towards the tire 11 to create a beneficial contrast and / or shadow effect above the markings 14 on the sidewall of the tire 11 for them to be easily perceptible by the camera 2.

[0061] Also shown in Fig. 3, a fixture 6 is provided on the side bar 5. The fixture 6 is optional, but preferable in various embodiments described herein and constitutes a means of mounting the cameras 2 and light sources 3 to the side bar 5. For instance, the fixture 6 may have the shape of a rod that extends vertically from the side bar 5, in a direction upwards from the floor or platform 7. The vertical axis V may also be referred to as a vertical axis, or extension of, the fixture 6.

[0062] In Fig. 3, the image capturing assembly 2, 3 is mounted to the fixture 6 of the elongated side bar 5, along the vertical axis V. This enables the camera 2 and the light source 3 to be positioned relative to each other in a vertical manner. Moreover, the camera 2 and the light source 3 are offset from one another along the vertical axis V. This creates room for inclination of the camera 2 and light source 3 with respect to each other. Preferably, the distance between the camera 2 and the light source 3 is about 30- 90 cm, preferably about 40-80 cm, more preferably about 50-70 cm. For instance, the distance between the camera 2 and the light source 3 can be described as being such that the distance is the same as between the light source 3 and the sidewall of the tire 11, in a way that the camera 2, the light source 3 and the tire 11 each represent a corner of a right-angled triangle with equal base and height.

[0063] In Fig. 3, the camera 2 is arranged above the light source 3. Both the camera 2 and the light source 3 are mounted to the fixture 6. Preferably, the camera 2 and the light source 3 are rotatably mounted to the fixture 6 to be able to adapt to different tire 11 diameters. The side bar 5, and thereby also the camera 2 and the light source 3, is arranged substantially parallel to and at a predetermined distance from the tire 11. In particular, both the camera 2 and the light source 3 are each arranged substantially equidistantly from the tire 11, namely at a distance D2 from the tire 11. The distance D2 is defined as the distance between the respective image capturing assembly 2, 3 and the tire 11, measured parallel to the wheel axis W. Preferably, the distance D2 is about 25 cm - 75 cm, such as 50 cm.

[0064] The camera 2 is inclined a camera angle a with respect to the wheel axis W and is configured to take an image of the bottom part 12 of the tire 11. The area which is to be captured by the camera is represented at its upper limit by the dash dotted line corresponding to the wheel axis W, and at its lower limit by the straight line pointing diagonally from the camera 2 towards the part of the tire 11 touching the floor or the optional platform 7. Preferably, the camera angle a is about 20°-60°, more preferably about 30°-50°, and most preferred 45°.

[0065] On the other hand, the light source 3 exhibits a light source angle P with respect to the wheel axis W and is configured to illuminate the bottom part 12 of the tire 11. In Fig. 3, since the camera 2 is inclined with respect to the wheel axis, it suffices that the light source angle P is equal to 0°, i.e. that it is directed straight ahead with respect to the tire 11 parallel to the wheel axis W. This is because the light from the light source 3 is scattered into a plurality of scattered light rays L1-L5 that scatter on the floor or platform 7 onto the tire 11 from a direction coming substantially from the floor or platform 7. Since the light rays L1-L5 illuminate the markings 14 on the bottom part 12 of the tire 11 straight on or slightly from below, this creates an enhanced contrast and / or shadow effect above the respective markings 14 of the tire 11, which makes them easily perceptible by the camera 2 due to the contrast created with respect to the remaining illuminated surface of the bottom part 12 of the tire 11. By ‘above the markings’ is meant in a direction gcloser to the center of the wheel axle.

[0066] Fig. 4 illustrates another example where the camera 2 is directed straight towards the tire 11 with a camera angle a of 0°, and where the light source angle P is also directed straight towards the tire 11 with a light source angle P of 0°,with respect to the wheel axis W, in a direction towards the bottom part 12 of the tire 11. Also in this case, the light rays L1-L5 of the light beam 4 are reflected in the floor / platform 7 and up towards the tire 11 to create the beneficial shadow effect above the markings 14 on the sidewall of the tire 11 for them to be easily perceptible by the camera 2.

[0067] Either way, the contrast and / or shadow effect described above is achieved by the light source 3 which is perceptible by the camera 2.

[0068] Preferably, either one of the camera 2 or light source 3 is directed straight ahead towards the tire 11, whereas the other is inclined towards the floor or platform 7, and in particular towards the bottom part 12 of the tire 11. In general, the light source 3 is preferably arranged above the camera 2 for the light rays L1-L5 to scatter advantageously on the floor or platform 7 before it reaches the tire 11. The light source 3 may alternatively be arranged under the camera 2 since the light source will create a contrast and / or shadow effect on the markings 14 even though the camera 2 may be directed straight towards the tire (i.e. with an angle a equal to 0°). As an example, when the light source 3 is directed straight towards the markings 14, the contrast between a side of the marking facing the light source and an upper side of the markings facing away from the floor or platform 7 will be greater and thus the markings are more clearly captured by the camera 2.

[0069] Fig. 5 illustrates a preferred embodiment where the camera 2 is arranged below the light source 3. Here, the camera 2 has a camera angle a of 0°, i.e. it is directed straight towards the sidewall of the tire 11. In contrast, the light source 3 has a light source angle P of 45° directed towards the bottom part 12 of the tire 11. This arrangement of the camera 2 and light source 3 with respect to

[0070] As another non-limiting example (not shown), there may be only one camera 2 provided at a predetermined distance from the vehicle 10, moving parallel to and in the same direction as the moving direction LA of the vehicle 10. The single camera may then capture images of the bottom part of the tire sidewall facing the floor / platform and send the images to an image processing machine 8 according to the one described above.

[0071] As yet another non-limiting example, a single camera 2 may be provided at a predetermined distance from the vehicle 10, being stationary with respect to the moving vehicle 10. In this case, the camera 2 may be directed to the bottom part of the tire sidewall facing the floor / platform in a rotatable manner to be able to rotate with respect to the tire 11 opposite the moving direction LA of the vehicle 10.

[0072] In all examples of the inventive concept presented above, the same principle is involved, namely to take advantage of the fact that the velocity in the moving direction of the vehicle compensates for the rotational velocity at the lower part of the tire sidewall. This is illustrated in Fig. 6 where the moving direction of the vehicle is represented by the arrow LA, and the rotational direction of the wheel is represented by the curved arrows. At the bottom part 12 of the tire sidewall, the bottom curved arrow points in a direction opposite to the moving direction arrow LA. Thus, the net velocity is lower at the bottom part 12 of the tire 11 than at the upper part thereof, which results in a more clear image of the bottom part 12 than the upper part of the tire sidewall. A camera photographing the bottom part 12 of the tire 11 may thus perceive an object that looks almost still, and therefore render a clear image to be sent to the image processing machine 8. Conversely, the top curved arrow points in the same direction as the moving direction arrow LA. Thus, the velocity at the upper part of the tire is believed to be be higher than the velocity of the moving vehicle 10. Thus, a camera photographing the upper part of the tire 11, opposite to the bottom part 12, would render a blurry image to be sent to the image processing machine 8.

[0073] Fig. 7 shows the vehicle inspection system 1 from above. Here, the vehicle inspection system 1 is shown further comprising an additional side bar 5’ mirrored in the longitudinal axis LA, on the opposite side from the vehicle 10 moving through the vehicle inspection system 1. The side bars 5, 5’ may be referred to as first and second side bars 5, 5’ or left and right side bars 5, 5’. Moreover, the longitudinal axis LA may also be defined as extending parallel to the elongated side bars 5, 5’, or vice versa. Fig. 7 also shows more clearly how the distance DI between neighboring image capturing assemblies 2, 3, is measured parallel to the longitudinal axis LA of the vehicle inspection system, but also perpendicular to the wheel axis W. Furthermore, it is shown how the distance D2 between the respective image capturing assemblies 2, 3 and the tire 11 is measured parallel to the wheel axis W. The side bars 5, 5’ are arranged on opposite sides of the vehicle 10 when the vehicle 10 passes through the vehicle inspection system 1. The vehicle inspection system 1 obtains information from all tires 11 of the vehicle when the vehicle passes through the vehicle inspection system, since both sides of the vehicle 10 are inspected by the image capturing assemblies 2, 3 at the same time.

[0074] Fig. 8 schematically illustrates the vehicle inspection system 1 according to an alternative embodiment. In the embodiment of Fig. 8, the vehicle inspection system 1 comprises a plurality of image capturing assemblies 2, 3 are arranged to capture images of the bottom part of the tire sidewalls on both sides of the moving vehicle 10. Hence, a first set of image capturing assemblies 2, 3 is arranged for taking images of the tires on a first side of the vehicle 10, such as the left side, wherein a second set of image capturing assemblies 2, 3 is arranged for taking images of the tires on the second side of the vehicle 10, such as the right side. For example, each of the first and second sets of image capturing assemblies 2, 3 comprises at least two image capturing assemblies 2, 3, such as three image capturing assemblies 2, 3 or more. The image capturing assemblies 2, 3 of the first set are arranged with a distance between each other, such as the distance DI. For example, each of the image capturing assemblies 2, 3 in the first set is arranged with the same distance to any adjacent image capturing assemblies 2, 3. Hence, the image capturing assemblies 2, 3 are spaced apart. For example, the image capturing assemblies 2, 3 of the first set are distributed along a first axis and may be aligned. The image capturing assemblies 2, 3 of the second set are, for example, arranged in a corresponding manner as the first set and are distributed along a second axis. The first and second sets of image capturing assemblies 2, 3 are spaced apart forming a space for the vehicle 10 between them. The first and second sets of image capturing assemblies 2, 3 are, e.g. arranged in parallel to each other. The first and second sets of image capturing assemblies 2, 3 are arranged in two rows parallel to the longitudinal axis LA. The first and second sets may be displaced in relation to each other in the longitudinal direction. Alternatively, the first and second sets mirror each other. Each of the image capturing assemblies 2, 3 is arranged on the fixture 6. For example, the fixtures 6 extends substantially vertically. Optionally, the fixtures 6 are fixed to the floor, such as directly to the floor or through a mount or similar. For example, the fixtures 6 are arranged as posts, rods, elongated plates, walls or similar. Alternatively, the fixtures 6 are arranged as movable stands or similar.

[0075] A method 100 for inspecting a tire with the vehicle inspection system above will be described in the following and in relation to Fig. 9. The method begins by rolling 101 the vehicle 10 into the vehicle inspection system 1. Optionally, the light source 3 then illuminates 105 an area 13 of the tire 11 which corresponds to the bottom part 12 of the tire 11. Next, the camera 2 captures 110 an image of the bottom part 12 of the illuminated tire 11 after which the image is sent 115 to an image processing machine 8 that assembles only the images or parts of the images of only the bottom part of the tire sidewall, performs image recognition and alerts an operator about a recommended tire replacement or the like.

Claims

CLAIMS1. A vehicle inspection system for obtaining information from a sidewall of a tire (11) of a moving vehicle (10) having wheels rotating around a wheel axis (W) for moving the vehicle in a moving direction, wherein the vehicle inspection system (1) comprises at least one camera (2) and an image processing machine (8), wherein the at least one camera (2) is configured to capture a plurality of images of a bottom part (12) of the tire sidewall while the vehicle (10) is moving in the moving direction, wherein the image processing machine (8) is configured to assemble only the images or parts of the images of only the bottom part (12) of the tire sidewall to obtain the information of the tire sidewall.

2. The vehicle inspection system according to claim 1, wherein each of said images or parts thereof corresponds to 140°or less of the tire sidewall.

3. The vehicle inspection system according to claim 1 or 2, wherein the image processing machine (8) is configured to assemble said images or parts of said images to obtain the information from 360° of the tire sidewall.

4. The vehicle inspection system according to any one of the preceding claims, further comprising a plurality of cameras (2).

5. The vehicle inspection system according to claim 5, further comprising a longitudinal axis (LA), and wherein the cameras (2) are distributed along the longitudinal axis (LA).

6. The vehicle inspection system according to claim 5, wherein the cameras are arranged in a first set of cameras and a second set of cameras, wherein the second set is spaced apart from and faces the first set.

7. The vehicle inspection system according to any of the preceding claims, further comprising at least one light source (3) configured to illuminate the bottom part (12) of the tire sidewall.

8. The vehicle inspection system according to claim 7, wherein the at least one light source (3) is non-aligned with respect to the at least one camera (2).

9. The vehicle inspection system according to any of the preceding claims, wherein the light source (3) is arranged above the camera (2).

10. A method for inspecting a sidewall of a tire of a moving vehicle with a vehicle inspection system (1) according to any of the preceding claims, comprising: rolling (101) the vehicle (10) into the vehicle inspection system (1); capturing (110) a plurality of images of the bottom part (12) of the tire sidewall from the moving vehicle; sending (115) the captured images to the image processing machine (8); and by means of the image processing machine (8) assembling only the images of only the bottom part (12) of the tire sidewall or assembling only the parts of the images of only the bottom part (12) of the tire sidewall to obtain the information of the tire sidewall.

11. The method of claim 10, comprising the step of capturing and / or assembling only the images or part of the images of the tire sidewall, wherein each of said images or parts thereof corresponds to 140°or less of the tire sidewall.

12. The method of claim 10 or 11, comprising the step of assembling said images or said parts thereof to obtain the information from 360° of the tire sidewall.

13. The method of any of claims 10 to 12, comprising the step of capturing images of the bottom part of the tire sidewall by means of a plurality of spaced apart cameras.

14. The method of claim 13, comprising the step of capturing said images in sequence as the vehicle passes the cameras.

15. The method of any of claims 10 to 14, comprising the step of illuminating the bottom part of the tire sidewall.

Images