KR101168399B1 - Irregularity inspection method for tire wheel - Google Patents

Abstract

PURPOSE: A tire wheel inspecting method is provided to determine an outward failure of a tire wheel with the high reliability by determining errors of a width and size of the tire wheel and inspecting patterns formed on a surface of the tire wheel. CONSTITUTION: A tire wheel inspecting method is as follows. Diffused lights are projected on a surface of a tire wheel having an irregular refraction plane. One or more cameras photograph the tire wheel so that images of the surface of the tire wheel are obtained(S200). Image information of the surface images is correspondent to points on 3D coordinates respectively having a color, a chroma, and brightness as independent variables, thereby being recorded(S300). At least one among the color, the chroma, and the brightness of the mapped surface images is controlled so that comparison images are obtained(S400). Whether a shape of the tire wheel is proper or not is determined by comparing reference images of the tire wheel(S500). A width of the tire wheel is measured by using the comparison images and compared with a reference width so that whether a width of the tire wheel is proper or not is determined.

Description

Irregularity inspection method for tire wheel}

The present invention relates to a method for inspecting a tire wheel that is combined with a tire to form a wheel, and more particularly, to a tire wheel inspection method that can effectively determine whether the tire wheel is appropriate.

A wheel is a driving device mounted on a rotating shaft and moving an object while rotating. Wheels used for automobiles and other various transport means may include a tire and a tire wheel coupled to the tire, and the tire and the tire wheel are independently produced and then assembled to form a wheel.

Among these, the tire wheel includes a wheel rim (Rim), which is a rim portion to which the tire is coupled, and a connection portion connecting the wheel rim to the hub hub. The wheel rims are connected to each other three-dimensionally to form a complex structure.

In addition, the wheel rim and the connecting portion may be in various forms due to the functional reasons for solidifying the tire wheel-to-tire engagement, improving the rotational characteristics of the wheels, or aesthetic reasons for enhancing the appearance of the wheels. Deformation is processed. As a result, the surface of the tire wheel may be refracted to form an irregular refractive surface.

Such tire wheels are essentially inspected for defects in an assembly line of a factory where tires and tire wheels are assembled, or a production line in which tire wheels are produced. However, due to the features described above, it is difficult to effectively inspect the tire wheels. there is a problem.

 In order to solve this problem, there is a method for inspecting the wheel of the vehicle using a robot camera as disclosed in Japanese Patent Laid-Open No. 2000-0072236. This is to perform the inspection to determine whether the error and defects through the image taken by the camera is called a conventional robot vision or vision system.

However, the existing vision system directly analyzes the captured image or simply compares it with the existing image. When applied to a relatively large and complex inspection object such as a tire wheel, the existing vision system facilitates the inspection object and the background part from the captured image. There was a problem that it is difficult to distinguish, which has a disadvantage in that the reliability of the test is greatly reduced.

In addition, the conventional lighting device used to obtain the image did not effectively expose the irregular refractive surface formed on the tire wheel surface, and thus it is difficult to obtain accurate image information of the entire tire wheel because only a specific part of the tire wheel surface is highlighted. There was.

Republic of Korea Patent Publication No. 2000-0072236 (2000.12.05), Figure 3

The technical problem to be solved by the present invention is to process the photographed image information in an easy-to-use state, thereby enabling precise inspection and inspection of the tire wheel to obtain accurate image information of the entire tire wheel. To provide a way.

The technical objects of the present invention are not limited to the above-mentioned technical problems, and other technical subjects not mentioned can be clearly understood by those skilled in the art from the following description.

Tire wheel inspection method according to an embodiment of the present invention, (A) irradiating diffused light to the surface of the tire wheel having an irregular refractive surface, (B) at least one camera photographing the tire wheel to the tire Obtaining a surface image of the wheel; (C) mapping the image information of the surface image corresponding to points on three-dimensional coordinates using hue, saturation, and brightness as independent variables; and (D) the ( (Da) obtaining a first comparison image which is an image in which the outer circumference of the tire wheel is separated from the background part by limiting at least one of the color, saturation, and brightness of the surface image mapped in step C). Obtaining a second comparison image which is an image in which the pattern of the surface of the tire wheel is shaped by limiting at least one of color, saturation, and brightness of the surface image mapped in step (C) (Db) and (C Mapped in step) Comparative image consisting of one or more steps selected from among steps (Dc) of obtaining a third comparison image which is an image in which the side surface of the tire wheel is separated from the background part by limiting at least one of the color, saturation, and brightness of the surface image. (Ea) measuring the diameter of the tire wheel from the first comparison image, and comparing it with a reference diameter to determine the suitability of the tire wheel size (Ea), the second comparison image and the Comparing the reference image of the tire wheel to determine the suitability of the tire wheel shape (Eb) and measuring the width of the tire wheel from the third comparison image, and comparing this with the size of the reference width to determine the width of the tire wheel. A suitability determining step includes one or more steps selected from among the steps Ec for determining suitability.

The diffused light of step (A) is a light source for irradiating straight light toward the surface of the tire wheel, and disposed between the light source and the tire wheel to pass the straight light, but the straight light in different directions It may be formed from a light irradiation part including a light diffusion plate to scatter.

The light irradiator may further include a light reflector disposed between the light diffuser plate and the tire wheel to re-reflect the diffused light deviating from the tire wheel toward the tire wheel.

The three-dimensional coordinates of the step (C) is a color coordinate represented by the rotation angle around the origin on one plane, chroma coordinates represented by the distance from the origin for each color coordinate on the plane, and It may be made of lightness coordinates expressed as the distance from the origin on a plane perpendicular to the plane.

The limit of the step (Da), the limit of the step (Db) and the limit of the step (Dc) are respectively limited within the allowable range, and the allowable range of the step (Da) is the color of the outer circumference of the tire wheel. , The saturation and the brightness range is made of only at least one range, and the allowable range of the step (Db) is a range made up of at least one range of the color, saturation, and brightness of the pattern of the tire wheel surface, The allowable range of the step (Dc) may be a range consisting of at least one range of color, saturation, and lightness of the tire wheel side surface.

The tolerance of each of the steps (Da), (Db), and (Dc) may be determined by a threshold that determines a lower limit or an upper limit of at least one of the color, the saturation, and the brightness. .

The suitability determination of step (E) is selected to include all or part of the tire wheel, such that the diameter of the tire wheel is measured, the pattern of the surface of the tire wheel is shaped, or the size of the width of the tire wheel. It may be made in the inspection area which is the area to be measured.

The surface image of the step (B) is taken with the tire wheel and the background portion that is the background of the tire wheel, the background portion and the tire wheel may be randomly disposed with each other.

The surface image is a planar image or a side image of the tire wheel captured according to a direction in which the camera is directed, the first comparison image and the second comparison image are obtained from the planar image, and the third comparison image is It may be obtained from the side image.

The camera of step (B) may be a color camera disposed perpendicular to each other such that one and the other face the front and side surfaces of the tire wheel, respectively.

In the tire wheel inspection method according to the present invention, an accurate surface image of the entire tire wheel can be obtained, and the image taken from the camera can be processed into a form that can be easily analyzed to accurately correct errors such as the size or width of the tire wheel. In this case, it is possible to determine whether the appearance of the tire wheel is defective by high reliability by inspecting the pattern formed on the surface of the tire wheel.

1 is a flow chart showing a tire wheel inspection method according to an embodiment of the present invention.
FIG. 2 is a block diagram illustrating a configuration of a tire wheel inspection apparatus for performing the inspection method of FIG. 1.
3 is a perspective view illustrating an example of an image photographing unit of the inspection apparatus of FIG. 2.
4 is a cross-sectional view illustrating the structure and operation of the image capturing unit of FIG. 3.
5 is a diagram illustrating a surface image of a tire wheel photographed by the image capturing unit of FIG. 3.
6A through 6C are diagrams illustrating comparative images obtained from the surface image of FIG. 5.
7A to 7D are diagrams illustrating a process of setting an inspection area using the surface image of FIG. 5.
8 is a diagram illustrating an example of an inspection result display screen obtained by the inspection method of FIG. 1.

Advantages and features of the present invention and methods for accomplishing the same will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms, and only the present embodiments make the disclosure of the present invention complete and the general knowledge in the technical field to which the present invention belongs. It is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the claims. Like reference numerals refer to like elements throughout.

1 to 8, the tire wheel inspection method according to an embodiment of the present invention will be described in detail.

1 is a flowchart showing a tire wheel inspection method according to an embodiment of the present invention, Figure 2 is a block diagram showing the configuration of a tire wheel inspection apparatus for performing the inspection method of FIG.

Referring to FIG. 1, in the method of inspecting a tire wheel according to the present invention, the tire wheel is positioned at an inspection point (S100), irradiating diffused light to the tire wheel, and photographing the tire wheel to obtain a surface image (S200). ), The mapping step of recording the image information of the captured image corresponding to the points on the three-dimensional coordinates (S300), obtaining a comparison image from the mapped surface image (S400), the diameter of the tire wheel using the comparison image, Inspecting a width and a shape, determining whether each is suitable or not (S500), and displaying a test result (S600).

In such an inspection method, diffused light irradiated onto the surface of the tire wheel is incident on the refracted surface of the tire wheel at various angles. Therefore, the irregular refraction surface can be revealed better, and thus the surface image of the tire wheel can be captured more accurately.

In addition, the surface image may be adjusted independently of each other through the mapping step (S300), color, saturation, and brightness. Accordingly, by restricting each variable within a predetermined range from the mapped surface image, a comparison image of the main body of the tire wheel and the background portion thereof may be separated from each other. By using the comparison image, the shape of the tire wheel itself may be more accurately determined. It is possible to recognize and determine whether the defect is higher with higher reliability. The inspection method of the tire wheel according to the present invention constitutes one automated inspection loop from the start to the end, and the inspection loop is again inspected for the other tire wheel after the inspection work for one tire wheel is finished. They can be connected to each other to start work. Thus, continuous inspection of a plurality of tire wheels is also possible.

Subsequently, referring to FIG. 2, the tire wheel inspection apparatus 1 for performing such an inspection method may process the image photographing unit 100, which photographs the surface image of the tire wheel, and photographs the surface image. The image processing unit 200 performs a task, the image display unit 300 displaying the inspection result to the outside, and an operation unit 400 for manipulating the image processing unit 200. The manipulation unit 400 may be formed to operate not only the image processor 200 but also the first camera 120 and the second camera 130 connected to the image processor 200, and the image display unit 300.

The image capturing unit 100 includes a light irradiation unit 110, a first camera 120, and a second camera 130.

The light irradiation unit 110 serves to irradiate diffused light to the surface of the tire wheel. As described above, the diffused light is incident on the surface of the tire wheel at various angles, thereby forming a pattern of the surface of the tire wheel formed by the refractive surface. The photographing process of the diffused light and the surface image will be described later in more detail.

The image capturing unit 100 includes a first camera 120 and a second camera 130. The first camera 120 and the second camera 130 may be color cameras arranged in a direction perpendicular to each other, the first camera 120 faces the front of the tire wheel, and the second camera 130 is the tire wheel. It may be disposed to face the side of. Therefore, the image capturing unit 100 may simultaneously obtain one or more surface images of the tire wheel. In this case, the first camera 120 and the second camera 130 are arbitrarily selected to distinguish one and the other camera, and the directions facing the first camera 120 and the second camera 130 are interchanged with each other. Can be. In addition, the image capturing unit 100 may further include one or more cameras in addition to the first camera 120 and the second camera 130.

The image processor 200 may be a PC or a workstation including a CPU and a peripheral device connected thereto. One or more PCs or workstations may be connected in parallel to form an image processor 200, thereby improving stability of the image processor 200. That is, one PC or workstation can work complementarily with another, and if one PC or workstation encounters a problem, another PC or workstation connected in parallel is urgently replaced, You can continue without interrupting the process that is in progress. Although not shown in the drawing, if necessary, the image processing unit 200 may be connected to a PLC (Programmed Logic Controller) programmed to operate an external device, through which the transport equipment for transporting the tire wheel is inspected by the tire wheel. It can be controlled to run in accordance with, or to stop the operation.

The image processing unit 200 maps the image information of the surface image of the tire wheel to correspond to various points of three-dimensional coordinates having Hue, Saturation, and Intensity as independent variables. Do the work. The mapping operation may be performed through a program embedded in the image processor 200, and the program may include a predetermined equation for converting a variable.

 The mapped surface image may be adjusted independently of each other in color, saturation, and brightness, and by using the extracted surface image, a comparison image, which is an image in which the tire wheel and the background part of the inspection object are separated from each other, may be extracted. In addition, by using the comparison image, the inspection of the tire wheel can be performed more closely. The mapping process, the comparison image acquisition process, and the inspection process of the image processor 200 will be described in more detail below.

The image display unit 300 may be a monitor installed in a work space such as an assembly line or a production line in which the tire wheel inspection apparatus 1 is installed, or may be a beam projector for magnifying and irradiating an image of such a monitor. The inspection result is displayed on the image display unit 300 and transmitted to the manager who manages the tire wheel inspection apparatus 1.

The tire wheel inspection apparatus 1 having such a configuration can be operated by the operation unit 400. The operation unit 400 may be an input device such as a computer keyboard or a mouse, and if necessary, may include an operation button provided separately from this. In the case of using a simply configured operation button to remove unnecessary keys, it will be easier to control the tire wheel inspection device (1).

Although not shown in the drawings, the tire wheel inspection apparatus 1 may also be connected to a warning lamp that can visually display the inspection result more effectively, or an alarm speaker that can emit a warning sound.

Hereinafter, referring to FIG. 3 to FIG. 5 together with FIG. 1, a step in which a tire wheel is positioned at an inspection point and a step of photographing a surface image will be described in more detail.

3 is a perspective view illustrating an example of an image capturing unit of the inspection apparatus of FIG. 2, FIG. 4 is a cross-sectional view for explaining the structure and operation of the image capturing unit of FIG. 3, and FIG. A diagram showing a surface image of a tire wheel.

When the inspection of the tire wheel W is started, as shown in FIG. 3, the tire wheel W is first conveyed to the inspection point. At this time, the image pickup unit 100 is located at the inspection point. The image capturing unit 100 may be formed in the form of a kind of inspection room including the housing 113, and one side of the housing 113 is formed as a door that can be opened and closed to operate an apparatus inside the image capturing unit 100. Or can be used to maintain.

The tire wheel W may be transferred using the wheel transfer part 500 to the inspection point. The wheel transfer part 500 may be configured using a known transfer means such as, for example, a conveyor belt. Guide bars 510 for guiding the transfer path of the tire wheel W are installed at both sides of the wheel transfer part 500.

The tire wheel W is moved while being mounted on the wheel transfer part 500. At this time, the tire wheel W is placed on the wheel transfer part 500 so that the front part faces upward. The side of the tire wheel (W) is formed with a wheel rim (Rim), which is a rim to which the tire is coupled, the wheel rim of the tire wheel (W) has a specific shape with the hub axis in the center of the tire wheel (W) It is connected via the connection. Hereinafter, the side or side portion of the tire wheel (W) refers to the rim portion to which the tire is coupled among the surfaces of the tire wheel (W), and the front or front portion of the tire wheel (W) refers to the tire wheel (W). Note that it refers to a circular disk surface located between the edges of the surface of the.

The connecting portion is a wheel spoke wheel spoke that connects the hub shaft and the wheel rim of the center of the tire wheel W to each other, and is located in front of the tire wheel W. The connection part reduces the air resistance to improve the rotational characteristics of the tire wheel W, improves the bearing capacity, or forms a specific pattern on the front surface of the tire wheel W that is exposed to the exterior of the tire wheel W. It may have a variety of shapes for the purpose of making it smooth.

In addition, the side portion where the wheel rim is located may also have a variety of other shapes to be in close contact with the bead (Bead) portion of the tire. 3 shows a side portion having a curved surface in which the curvature is reversed more than once.

That is, the entire surface of the tire wheel W including the front part and the side part may be refracted in a complicated form. In particular, the front portion of the tire wheel W can be more intricately refracted to form a particular pattern. The pattern formed by the front portion of the tire wheel W is mainly a rotationally symmetrical shape as shown, but need not always be such a shape, it is also possible to be formed in a non-standardized shape, asymmetrical shape. For this reason, an irregular refractive surface may be formed on the surface of the tire wheel W, and the irregular refractive surface forms a three-dimensional shape on the surface of the tire wheel W.

The tire wheel (W) having this feature is located along the wheel transfer unit 500 (see the arrow in FIG. 3) and passes through the inlet port 114 provided on one side of the housing 113 and is positioned at the inspection point (see FIG. 3). S100).

Referring to FIG. 4, the light irradiator 110, the first camera 120, and the second camera 130 are disposed inside the housing 113. The first camera 120 may be positioned above the housing 113, and the second camera 130 may be mounted on the guide bar 510 to be positioned below the housing 113. The first camera 120 and the second camera 130 are disposed perpendicular to each other.

The light irradiator 110 is disposed between the light source 111 for irradiating straight light toward the surface of the tire wheel W from the upper side of the housing 113, and disposed between the light source 111 and the tire wheel to direct the straight light in different directions. It includes a light diffusion plate 112 to scatter. The light reflector 116 may be further included between the light diffuser plate 112 and the tire wheel W to be perpendicular to the light diffuser plate 112. The light source 111 may be configured by, for example, arranging a plurality of high brightness LEDs (Light Emitting Diodes) in parallel.

Straight light irradiated from the light source 111 (see the small arrow directly below the light source 111) reaches the light diffusion plate 112 and then diffuses in different directions. In the case of the straight light is incident in one direction toward the surface of the tire wheel (W), which results in a refracted surface that does not light only a portion of the refracting surface or the light does not reach, so conventional lighting using the straight light is a tire wheel ( W) The shape of the surface cannot be revealed effectively. The light diffuser plate 112 may be made of, for example, a translucent acrylic resin, or the like, and the diffused light L may be scattered or refracted and reflected by the straight light reaching the inside of the light diffuser plate 112. Can be obtained by repeating

Therefore, the diffused light L is irradiated below the light diffuser plate 112. The diffused light L travels downward, but does not go straight toward the tire wheel W, but spreads around the tire wheel W. FIG. At this time, the diffused light L, which is out of the tire wheel W, may be reflected by the light reflecting plate 116 to be directed toward the tire wheel W again. The propagation path of the diffused light L reflected back by the light reflector 116 is changed again. Accordingly, the diffused light L may be incident on the surface of the tire wheel W at different angles, and may reach different refractive surfaces of the tire wheel W surface. Therefore, the diffused light (L) is reflected from each of the refracting surfaces it is possible to effectively reveal the shape of the entire tire wheel (W).

Through such a process, the reflected light L ′ of the diffused light L reflected from the surface of the tire wheel W may form a pattern formed in a specific shape of the surface of the tire wheel W, in particular, the front part. The reflected light L 'travels toward the first camera 120 positioned above the housing 113, and the first camera 120 photographs the tire wheel W to capture the surface image of the front surface of the tire wheel W. FIG. The second camera 130 acquires the surface image of the side surface of the tire wheel W (S200). The outer side portion of the side of the tire wheel (W) is reflected relatively brightly reflected by the reflected light (L '), through which it is possible to accurately measure the width of the side portion, that is, the width of the tire wheel (W).

Although not shown in the drawings, a part of the light diffusion plate 112 positioned directly below the first camera 120 may be cut for image capturing. In addition, the first camera 120 may be disposed to be exposed under the light diffusion plate 112 through the cut portion.

As shown in FIG. 5, the surface image obtained through this process is an image (left) for inspecting the size, that is, the diameter of the tire wheel (W), and a shape, that is, the shape of the front portion of the tire wheel (W). The image (center) and the image for inspecting the width of the tire wheel (W) are divided (right). Among these, both the surface image for inspecting the diameter of the tire wheel (W) and the surface image for inspecting the shape of the tire wheel (W) may be obtained from the first camera 120, the width of the tire wheel (W) Surface image for examining the may be obtained from the second camera (130). The surface image may be a planar image or a side image of the tire wheel captured according to the direction in which the camera is directed.

In addition, the surface image is to capture the entire tire wheel (W) entered the inspection position, the tire wheel (W) and the background portion was taken together, the tire wheel (W) and the background portion at random in the surface image Can be deployed. That is, in the case of inspecting the tire wheel W using a detection sensor or a color sensor fixed at a specific position, it is inconvenient that the tire wheel W should be aligned exactly at the inspection position in order to minimize the measurement error. However, since the tire wheel (W) captured in the surface image is used as the entire data through the image processing process to obtain the mapping and comparison image to be described later, it does not need to be aligned to be located at the center in the surface image. will be. In this case, the background part may be, for example, a part of the examination room photographed together with the tire wheel W or a part of the conveyor belt installed to transport the tire wheel W.

Hereinafter, referring to FIGS. 6A to 8 together with FIG. 1, a mapping step of recording image information of the surface image, obtaining a comparison image from the mapped surface image, inspecting the comparison image and determining whether there is a defect; and The steps for displaying the test results are described in more detail.

6A to 6C are views illustrating comparative images obtained from the surface image of FIG. 5, and FIGS. 7A to 7D are views illustrating a process of setting an inspection area using the surface image of FIG. 5, and FIG. 8 is FIG. 1. Fig. 1 shows an example of a test result display screen obtained by the test method shown in Figs.

Surface images photographed through the above-described process are mapped by the image processor (see 200 of FIG. 2). The mapping process is a process of moving image information of the captured image onto three-dimensional spatial coordinates using color, saturation, and brightness as independent variables, respectively, and through this process, the image information of the surface image is displayed on the three-dimensional spatial coordinates. It can be recorded corresponding to the points. Image information of the mapped surface image may be recorded in a manner that is digitized and stored in a data storage device connected to the image processor 200.

 Hue, Saturation (color saturation or saturation), and Intensity are variables used to define a color image. RGB, that is, a set of points corresponding to three-dimensional spatial coordinates having three primary colors of red, green, and blue as variables. That is, the image information is stored in a manner that the coordinates of one point in the RGB space per pixel defining the image correspond. In such a case, brightness and saturation can be additionally adjusted. For example, when brightness is adjusted, the color information of the image is distorted by adjusting the gamma value of the entire image information.

On the other hand, a space having Hue, Saturation, and Intensity as independent variables (hereinafter, referred to as HSI color space) can determine saturation and brightness independently for each color information. Saturation or brightness of the image information can be adjusted without distortion of the information. In addition, by applying this, it is possible to enhance or vice versa the brightness or saturation of the image independently of the color information. The HSI color space includes color coordinates expressed in degrees of rotation about an origin on one plane, chroma coordinates expressed in distance from the origin for each color coordinate on the plane, and on a plane perpendicular to the plane. It may be a three-dimensional space consisting of brightness coordinates expressed as a distance from the origin of.

Accordingly, when the surface image mapped to the HSI color space is appropriately processed, the converted comparison image may be obtained to facilitate inspection of the tire wheel (S400). The comparative image may be achieved through a method of restricting at least one of color, saturation, and brightness, which are variables defining the HSI color space.

The hue value, the saturation value, and the brightness value defining the comparison image each have unique steps. The color value represented by the change of angle in the HSI color space may have a value between 0 and 359, and a unique color value may be assigned to each of the different colors. For example, red may have a value of 0, green may have a value of 120, and blue may have a value of 240. On the other hand, the saturation and the brightness can be set by dividing each step into 256 steps, and can have a value of 0 to 255, respectively, according to the intensity and intensity of the color.

At this time, the tire wheel to be inspected has an original color range, a saturation range, and a brightness range distinguished from the background portion. Therefore, if at least one of the color, saturation, and brightness of the mapped surface image is limited within a certain allowable range, portions having colors, saturation, and brightness exceeding or falling short of the allowable range may be removed, and thus tires may be removed. The first comparative image, in which the outer periphery of the wheel is completely separated from the background part, the second comparative image, in which the pattern of the tire wheel surface is effectively shaped, and the outline of the tire wheel side part are emphasized, so that the side of the tire wheel is separated from the background part. At least one selected from among the third comparative images which are separated images may be obtained. Color, saturation, and brightness may be limited in various ways depending on the inspection object.

Obtaining at least one selected from the first comparison image, the second comparison image, and the third comparison image includes obtaining one image selected from the first comparison image, the second comparison image, and the third comparison image; It means both the case of obtaining two or more images combining the other one, and the case of obtaining three kinds of comparative images at once. When three comparison images are obtained at the same time, the determination of suitability for the size, shape, and width of the tire wheel may also be performed at the same time, so that the inspection process of the tire wheel may be comprehensively and quickly performed. The first comparison image and the second comparison image may be obtained from a planar image in which the front part of the tire wheel is captured, and the third comparison image may be obtained from a side image in which the side part of the tire wheel is captured.

The allowable range from which the first comparative image may be obtained may be at least one of a color range, a saturation range, and a brightness range of the outer circumference of the tire wheel, and the remaining region may be an excluded range. The allowable range from which the comparative image can be obtained may be at least one of the color range, the saturation range, and the brightness range of the pattern of the tire wheel surface, and the remaining region may be the excluded range. In addition, the allowable range in which the third comparative image may be obtained may be at least one of a range of color, a range of saturation, and a range of brightness of the tire wheel side, and the other area may be an excluded range.

Specifically, such an allowance is determined through a method of setting a threshold that determines the lower limit or the upper limit of at least one of color, saturation, and lightness.

 When all or part of the tire wheel to be inspected is painted, it is effective to obtain a comparison image by setting thresholds for each of hue, saturation, and brightness. On the other hand, for most tire wheels that are not painted or have an achromatic color (such as white, silver, or black), there is no need to set thresholds for each of hue, saturation, and lightness. It may be sufficient to set a threshold for brightness to effectively reveal the reflected light of the reflected diffused light.

Examples of comparative images obtained through this process are shown in FIGS. 6A to 6C.

First, referring to FIG. 6A, the first comparative image has a form in which the outer periphery of the tire wheel is completely separated from the background part. Therefore, by measuring the diameter of the tire wheel itself, and comparing it with the standardized diameter of the data it is possible to precisely determine the size error of the tire wheel. At this time, the reference diameter is the size of the diameter set to the target value to be manufactured of the tire wheel to be inspected, and is digitized and stored in the image processor (see 200 of FIG. 2). The image processor 200 has data of reference diameters for various types of tire wheels.

The first comparison image may be obtained by restricting each of hue, saturation, and brightness within a required allowable range, and specifically, may be obtained by adjusting a threshold for determining a lower limit or an upper limit of brightness.

The threshold may be adjusted on the setting screen of the image processing unit (see 200 of FIG. 2), and while operating the operation unit (see 400 of FIG. 2) while watching the setting screen of the image display unit (see 300 of FIG. 2). Can be done. The threshold may be a lower limit of brightness, and the step of brightness may have a value between 0 and 255 as described above. For example, when the threshold value is set to 100, the pixels having the brightness below the threshold value among the pixels forming the first comparison image are not activated. As shown in FIG. 6A, only the outer circumference and the surface of the tire wheel are clearly shown. You can get a comparative image.

If the threshold is not set properly, the reliability of the test may be lowered. In such a case, the threshold may be reset after stopping any one of the steps of the test process. After resetting the thresholds, you can go back to the step where you stopped.

Subsequently, referring to FIG. 6B, the second comparative image is also an image in which at least one of color, saturation, and lightness is limited so that the pattern of the tire wheel surface is effectively shaped, and diffused light irradiated onto the tire wheel (see L in FIG. 4). ) Is an image in which the refractive surface of the tire wheel surface is effectively shaped by the reflected light (see L ′ in FIG. 4). The second comparison image may be, for example, an image in which the shadow of the tire wheel surface is emphasized so that the shape or pattern of the tire wheel surface may be effectively determined, and the black and white image in which the color and saturation values are limited to a single value, respectively. Can be. In this case, the black and white image may be obtained by setting the upper and lower limits of the color and the saturation at the same value and not setting the threshold value at the brightness, and thus, the difference in the intensity of the reflected light may cause The refractive surfaces can be effectively revealed.

As described above, in the case of a tire wheel painted in whole or in part, a color image other than a black and white image may be used, and both thresholds for color and saturation may be used to emphasize the color displayed on the tire wheel surface. A second comparative image may be obtained.

Comparing the second comparison image with the reference image of the tire wheel under inspection, it is possible to inspect the overall shape of the tire wheel, that is, the appearance.

The appearance inspection of the tire wheel is a known image recognition algorithm that statistically grasps and analyzes a state in which pixels constituting the second comparative image are distributed on a two-dimensional plane, or changes in saturation and maximum or minimum values of brightness, or the like. It may be achieved by using a combination of known image filtering processes such as image dithering and correcting an image by grasping an inter-pixel distribution pattern.

In addition, since the outer shape of the tire wheel is effectively exposed by the effect of the above-described diffused light (L), whether or not the shape is defective can be determined with high reliability. The inspection of the tire wheel's appearance may include determining whether the pattern of the tire wheel surface is consistent with the reference image, detecting cracks on the tire wheel surface, and detecting whether the tire wheel outer periphery is refracted. Can be.

At this time, the reference image is stored in the above-described image processing unit (see 200 of FIG. 2), and photographed in advance a standard model of the tire wheel to be inspected. The reference image may be input in advance before the inspection operation starts through a registration screen for registering the reference image. The reference image may be composed of a plurality of images photographed at various angles with respect to one tire wheel, and the reliability of defect determination may be further improved through inspection of the reference image.

Referring to FIG. 6C, the third comparative image is formed by completely separating the side surface of the tire wheel from the background portion. Like the first comparison image, the third comparison image may also be obtained by adjusting a threshold which is a lower limit of brightness. Since the third comparative image is used to measure the width of the tire, the refractive surface of the surface is not exposed, but the outer side and the background side of the side are clearly separated. Therefore, the error of the tire wheel width can be accurately determined using the third comparison image. The method of adjusting the threshold may be the same as the method of adjusting the first comparison image.

On the other hand, if necessary, it is possible to arrange the light source and the light diffuser plate (refer to 111 and 112 of FIG. 3 respectively) to face the side of the tire wheel, thereby inspecting another specific shape of the tire wheel side part. It can be done.

Comprehensive inspection of the size and shape of the tire wheel can be performed simultaneously using the comparative images having such characteristics.

The inspection of the comparison image is to measure the diameter from the outer circumference of the tire wheel revealed in the first comparison image, and compare it with the data base diameter to determine whether the tire wheel size is suitable or not suitable, or the second comparison image Comparing the above-described reference image of the tire wheel with each other to determine whether the shape of the tire wheel shape or not, or measure the width of the tire wheel from the outer portion of the tire wheel revealed in the third comparison image, and the data It may be at least one of determining whether the tire wheel width is suitable or incompatible with the width (S500). That is, the inspection of the size of the tire wheel, the inspection of the shape, or the inspection of the width may be performed alone for each obtained comparative image, two inspections selected from three may be performed simultaneously, or all three inspections may be performed at once. Can be.

At this time, the reference width is the size of the tire wheel width set to the target value to be manufactured of the tire wheel to be inspected, and is digitized and stored in the image processor (see 200 of FIG. 2). The image processor 200 has data of reference widths for various types of tire wheels.

The inspection of the comparison image may be performed in the image processing unit 200, and the inspection process of the image processing unit 200 may be checked through the progress screen of the inspection process displayed on the image display unit 300. In this case, the inspection of the comparison image may be performed in the inspection region selected to include all or a portion of the tire wheel. The inspection area reduces the inspection time of the tire wheel by measuring the size and width of the tire wheel or comparing the shape of the tire wheel only in a limited area. Like the threshold setting process, the inspection area setting process may be performed before the inspection starts. If necessary, the inspection region may be temporarily suspended and then proceeded.

7A to 7D, the inspection area setting process may be performed before the inspection process starts as described above. Therefore, it is possible to set inspection areas of different sizes using the surface image of the tire wheel being photographed by the camera, and the set inspection area is reflected in the comparison image obtained after the mapping step S300.

The process of setting the inspection area may be performed for the planar image and the side image of the tire wheel, respectively. The inspection area is displayed as a rectangular window on the surface image. In other words, the size of the inspection area for inspecting the diameter of the tire wheel may be set to an area slightly wider than the area where the tire wheel is located as shown in FIG. 7A (see area A). This takes into account the amount of motion of the tire wheel carried by the wheel transporter (see 500 in FIG. 3).

After setting the inspection area, the actual measurement value of the tire wheel diameter is input to the measurement value setting box (see B) in contact with the outer circumference of the tire wheel as shown in FIG. 7B. Through this, the distance between pixels in the image may be converted into the diameter of the actual tire wheel, and the size error of the tire wheel may be accurately determined by measuring the distance between pixels of the tire wheel captured in the comparison image.

In the case of the inspection area for determining the suitability of the tire wheel appearance, it is formed to contact the outer circumference of the tire wheel as shown in FIG. 7C (see region C). As a result, the background portion outside the inspection area is excluded, thereby making it possible to efficiently inspect the appearance of the tire wheel.

The inspection area for inspecting the width of the tire wheel may be selected to include only part of the tire wheel as shown in FIG. 7D (see area D). At this time, the inspection area is an area including a boundary consisting of the outline of the tire wheel side, the horizontal line passing through the center of the inspection area may be a reference line for determining the reference width of the tire wheel to be inspected. That is, the tire wheel photographed while being mounted on the wheel transfer unit (see 500 in FIG. 4) has a length in the vertical direction, that is, the height represents the width, and when the reference line is set at the height corresponding to the reference width, the tire It is possible to determine whether there is an error in the size of the tire wheel width by measuring only the height difference between the height of the tire wheel side and the reference line without measuring the entire wheel width. At this time, the reference line for defining the length in the longitudinal direction, that is, the height may be set in the horizontal direction, and the horizontal line passing through the center of the inspection area becomes the reference line set for determining the reference width of the tire wheel.

Accordingly, as shown in the drawing, by measuring the match between the outline of the side of the tire wheel formed in the horizontal direction in the third comparison image and the horizontal line passing through the center of the inspection area, it is possible to accurately determine whether the tire wheel width is in error. Can be. Also, in this case, the inspection time can be significantly shortened due to the inspection area formed small around the outline of the tire wheel side.

 After the step of determining the inspection and bad state, the inspection result is displayed (S600). The test result may be displayed through the image display unit 300 (refer to 300 of FIG. 2), and other display devices or alarm devices may be further used as described above.

8 shows an example of a display screen displaying such a test result.

The inspection result display screen may be configured in various forms to effectively transmit information to the manager who manages the tire wheel inspection apparatus. For example, the inspection result display screen as shown is shown with a display window for displaying the image information of the tire under inspection, and a determination window for displaying the non-conformance, the inspection method described so far in a loop to When applied to the tire wheel continuously, a display window that statistically displays each inspection result may be configured together.

Although the present invention has been described above with reference to the accompanying drawings, those skilled in the art can understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. There will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

1: tire wheel inspection apparatus 100: the imaging unit
110: light irradiation unit 111: light source
112: light diffusion plate 113: housing
114: inlet 115: outlet
116: light reflector 120: first camera
130: second camera 200: image processing unit
300: image display unit 400: operation unit
500: wheel transfer unit 510: guide bar
A, C, D: Inspection area B: Measurement value setting box
W: tire wheel L: diffused light
L ': reflected light

Claims (10)

(A) irradiating diffused light to the surface of the tire wheel having an irregular refractive surface;
(B) at least one camera photographing the tire wheel to obtain a surface image of the tire wheel;
(C) a mapping step of recording the image information of the surface image in correspondence with points on three-dimensional coordinates using hue, saturation, and brightness as independent variables;
(D) obtaining a first comparison image which is an image in which the outer circumference of the tire wheel is separated from the background part by limiting at least one of color, saturation, and brightness of the surface image mapped in step (C) (Da),
(Db) obtaining a second comparison image which is an image of which the pattern on the surface of the tire wheel is shaped by limiting at least one of the color, the saturation, and the brightness of the surface image mapped in the step (C); and
In the step (Dc) of obtaining a third comparison image which is an image in which the side surface of the tire wheel is separated from the background part by limiting at least one of the color, saturation, and brightness of the surface image mapped in the step (C). Obtaining a comparative image consisting of one or more selected steps; And,
(E) measuring the diameter of the tire wheel from the first comparison image, and comparing this with a reference diameter to determine whether the tire wheel size is appropriate (Ea),
Determining an appropriateness of the tire wheel shape by comparing the second comparison image with a reference image of the tire wheel (Eb) and
An appropriateness determining step comprising one or more steps selected from among steps (Ec) of measuring the width of the tire wheel from the third comparison image and comparing the tire wheel width with a reference width to determine whether the tire wheel width is appropriate; Tire wheel inspection method comprising a. The method of claim 1,
The diffused light of step (A),
A light source for irradiating straight light toward the surface of the tire wheel;
And a light diffuser disposed between the light source and the tire wheel to pass the straight light and scatter the straight light in different directions. The method of claim 2,
The light irradiator further includes a light reflector disposed between the light diffuser plate and the tire wheel to reflect the diffused light off the tire wheel toward the tire wheel. The method of claim 1,
The three-dimensional coordinates of the step (C) is a color coordinate represented by the rotation angle around the origin on one plane, chroma coordinates represented by the distance from the origin for each color coordinate on the plane, and A tire wheel inspection method comprising lightness coordinates expressed as a distance from an origin on a plane perpendicular to the plane. The method of claim 1,
The restriction of the step (Da), the restriction of the step (Db) and the restriction of the step (Dc) are respectively limited within the allowable range,
The allowable range of the step (Da) is a range consisting of at least one of the color, saturation, and brightness of the outer circumference of the tire wheel,
The allowable range of the step (Db) is a range consisting of at least one of the color, saturation and brightness of the pattern of the tire wheel surface,
The allowable range of the step (Dc) is a tire wheel inspection method is a range consisting of only at least one of the range of color, saturation and brightness of the tire wheel side. 6. The method of claim 5,
The tolerance of each of the steps (Da), (Db) and (Dc) is determined by a threshold that determines the lower or upper limit of at least one of the color, the saturation and the brightness. Wheel inspection method. The method of claim 1,
The suitability determination of step (E) is selected to include all or part of the tire wheel, such that the diameter of the tire wheel is measured, the pattern of the surface of the tire wheel is shaped, or the size of the width of the tire wheel. Tire wheel inspection method that is made in the inspection area that is the area to be measured. The method of claim 1,
The surface image of the step (B) is a tire wheel and a background portion that is the background of the tire wheel is taken together, the background portion and the tire wheel is a tire wheel inspection method that is randomly arranged. The method of claim 1,
The surface image is a planar image or a side image of the tire wheel captured according to the direction toward the camera,
The first comparison image and the second comparison image is obtained from the planar image, the third comparison image is obtained from the side image tire wheel inspection method. The method of claim 1,
The camera of step (B) is a tire wheel inspection method, wherein one and the other is a color camera disposed vertically with each other facing the front and side of the tire wheel.

Images