Tire wireless tag location inspection method, tire wireless tag location inspection device, and tire wireless tag location inspection program

Abstract

To provide a tire wireless tag position inspection method, tire wireless tag position inspection device, and tire wireless tag position inspection program, which enable detection of the position of a wireless tag embedded in a tire from an image captured by a tire transmitting X-ray device.SOLUTION: An acquisition unit 40 acquires a radiographic image captured by an image capturing unit by irradiating a tire having a wireless tag embedded therein with X-rays from an X-ray tube while being conveyed. An extraction unit 42 extracts a bead image on a serial side from the captured image. A computation unit 44 computes an elliptic equation matching a predetermined reference image and the bead image, and detects the position of the wireless tag using the elliptic equation.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a tire wireless tag position inspection method, a tire wireless tag position inspection apparatus, and a tire wireless tag position inspection program. [Background Art]

[0002] Patent Document 1 proposes a tire including a pair of beads each having a bead core and a bead filler extending outward in the tire radial direction of the bead core, a reinforcing resin layer provided along the bead filler, and an RFID tag as an electronic component unit disposed in contact with the reinforcing resin layer.

[0003] For such a tire having a wireless tag such as an RFID embedded in a rubber structure, the RFID tag embedded in the tire communicates with a reader as an external device, thereby enabling tire manufacturing management, usage history management and the like. [Prior Art Literature] [Patent Literature]

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 2022-101234 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] When a wireless tag is embedded in a tire as in Patent Document 1, there is a possibility that the position and posture of the wireless tag in the finished tire are displaced compared to those at the time of embedding due to green tire deformation after embedding the device into the green tire member and the flow of rubber during vulcanization.

[0006] Depending on the embedding position of the wireless tag in the tire, the wireless tag may not exhibit the expected performance, and therefore a non-destructive method for measuring the embedding position and posture of the wireless tag in the finished tire after vulcanization is required.

[0007] One method for high-speed, non-destructive testing of large quantities of tires is through-type X-ray equipment. However, due to the X-ray focal length, the images captured by tire-through-type X-ray equipment are highly distorted, and it has been considered difficult to estimate the positional information of the projected object from the X-ray images without CT, which reconstructs the images from a large number of images.

[0008] The purpose of this disclosure is to provide a tire wireless tag position inspection method, a tire wireless tag position inspection device, and a tire wireless tag position inspection program that can detect the position of a wireless tag embedded in a tire from an image captured by a tire-passing X-ray device. [Means for solving the problem]

[0009] To achieve the above objective, the tire wireless tag position inspection method according to the first embodiment involves a computer irradiating the tire with X-rays while the tire in which the wireless tag is embedded is being transported to acquire an image, extracting a predetermined bead image from the image, calculating an ellipse equation that matches a predetermined reference image from the extracted bead image, and using the calculated ellipse equation to detect the position of the wireless tag.

[0010] The tire wireless tag position inspection method according to the second embodiment is the tire wireless tag position inspection method according to the first embodiment, wherein the computer extracts the bead on the serial side as the predetermined bead.

[0011] The tire wireless tag position inspection method according to the third embodiment is the tire wireless tag position inspection method according to the first embodiment or the second embodiment, wherein the computer calculates the ellipse formula by reducing the number of parameters in the ellipse formula.

[0012] The tire wireless tag position inspection method according to the fourth embodiment is the tire wireless tag position inspection method according to the third embodiment, wherein the computer calculates the ellipse formula using four parameters of the ellipse formula.

[0013] The tire wireless tag position inspection method according to the fifth embodiment is a tire wireless tag position inspection method according to any one of the first to fourth embodiments, wherein the computer corrects the ellipse to a perfect circle and detects the position and angle of the wireless tag from the corrected perfect circle.

[0014] A tire wireless tag position inspection device according to the sixth embodiment includes: an acquisition unit that acquires an image taken by irradiating a tire with an embedded wireless tag with X-rays while the tire is being transported; an extraction unit that extracts a predetermined bead image from the image acquired by the acquisition unit; a calculation unit that calculates an ellipse formula that matches a predetermined reference image from the bead image extracted by the extraction unit; and a detection unit that detects the position of the wireless tag using the ellipse formula calculated by the calculation unit.

[0015] The tire wireless tag position inspection program according to the seventh embodiment involves a computer that acquires an image taken by irradiating a tire with an embedded wireless tag with X-rays during transport, extracts a predetermined bead image from the image, calculates an ellipse equation that matches a predetermined reference image from the extracted bead image, and uses the calculated ellipse equation to detect the position of the wireless tag. [Effects of the Invention]

[0016] This disclosure provides a tire wireless tag position inspection method, a tire wireless tag position inspection device, and a tire wireless tag position inspection program that can detect the position of a wireless tag embedded in a tire from an image captured by a tire-passing X-ray device. [Brief explanation of the drawing]

[0017] [Figure 1] This is a block diagram showing the schematic configuration of the tire wireless tag position inspection device according to this embodiment. [Figure 2] This is a schematic diagram of a tire-pass type X-ray apparatus. [Figure 3]It is a functional block diagram showing the functional configuration of the processing device of the tire wireless tag position inspection apparatus according to the present embodiment. [Figure 4] It is a diagram for explaining the positional relationship of upper and lower beads on a captured image. [Figure 5] It is a diagram showing an example of a captured image and upper and lower bead images. [Figure 6] It is a diagram for explaining an example of failure in extracting an upper bead image. [Figure 7] It is a diagram showing an example in which only the upper bead is extracted by extracting an ellipse through edge extraction. [Figure 8] It is a diagram showing RFID detection. [Figure 9] It is a diagram for explaining extraction of an RFID region. [Figure 10] It is a flow chart showing an example of the flow of processing performed by the processing device of the tire wireless tag position inspection apparatus according to the present embodiment MODE FOR CARRYING OUT THE INVENTION

[0018] Hereinafter, embodiments for implementing the technology of the present disclosure will be described in detail with reference to the drawings. Components and processes that perform the same function and operation are assigned the same reference numerals throughout the drawings, and duplicate descriptions may be omitted as appropriate. The present disclosure is not limited to the following embodiments in any way, and can be implemented with appropriate modifications within the scope of the object of the present disclosure.

[0019] The tire wireless tag position inspection apparatus according to the present embodiment detects the position of an RFID (radio frequency identification) as an example of a wireless tag embedded in a tire.

[0020] During tire molding, when RFID tags coated with rubber sheets are embedded in the tire, the raw tire deforms, changing the embedded position of the RFID tags. Furthermore, vulcanization causes the tire to flow, which further alters the RFID position, making it uncertain whether the RFID tags will be positioned as intended. Therefore, the tire wireless tag position inspection device according to this embodiment inspects the position of the RFID tags embedded in the tire.

[0021] Figure 1 is a block diagram showing the schematic configuration of the tire wireless tag position inspection device according to this embodiment.

[0022] As shown in Figure 1, the tire wireless tag position inspection device 10 includes a tire-through type X-ray device 12 and a processing device 20.

[0023] The tire-pass-through type X-ray apparatus 12 comprises an X-ray tube 14 and an imaging unit 16. As tires moving on a conveyor belt pass through the tire-pass-through type X-ray apparatus 12, X-rays are irradiated onto the tires from the X-ray tube 14, pass through the tires, and are imaged in the imaging unit 16. This allows for the acquisition of an X-ray image.

[0024] Here, we will describe the tire-pass type X-ray apparatus 12. Figure 2 is a schematic diagram of the tire-pass type X-ray apparatus 12.

[0025] The tire-passing type X-ray apparatus 12 is positioned on a conveyor consisting of multiple rollers 18. As shown in Figure 2, the tire T is transported by the multiple rollers 18 and passes through the tire-passing type X-ray apparatus 12.

[0026] As shown in Figure 2, the X-ray tube 14 is positioned above the multiple rollers 18 and irradiates the side of the tire T with X-rays from above. In this embodiment, as an example, as shown in Figure 2, there are two X-ray tubes 14, with one X-ray tube 14 irradiating approximately half of the tire T with X-rays and the other X-ray tube 14 irradiating approximately the remaining half of the tire T with X-rays.

[0027] The imaging unit 16 is located below the X-ray tube 14 and between a plurality of rollers 18. It generates an X-ray image by detecting the X-rays that are irradiated onto and transmitted through the tire T. In this embodiment, a linear X-ray detector is used, and there are two imaging units 16 corresponding to the two X-ray tubes 14. That is, as the tire T is transported by the plurality of rollers 18, X-ray imaging is performed by the two imaging units 16, thereby obtaining an X-ray image of the entire tire T. In this embodiment, it is described as having two X-ray tubes 14 and two imaging units 16, but the number of X-ray tubes 14 and imaging units 16 is not limited to two; there may be one of each, or three or more.

[0028] On the other hand, as shown in Figure 1, the processing unit 20 includes a CPU (Central Processing Unit) 22, ROM (Read Only Memory) 24, RAM (Random Access Memory) 26 such as volatile memory, auxiliary storage device 34 such as a hard disk drive (HDD), an operation unit 28, a display unit 30, and a communication interface 32. These components, the CPU 22, RAM 26, ROM 24, auxiliary storage device 34, operation unit 28, display unit 30, and communication interface 32, are connected to each other via a bus 36 so that data and commands can be exchanged between them.

[0029] The control unit 28 is equipped with a keyboard or similar interface, allowing for the input of various information. The display unit 30 displays various information. The communication interface 32 is connected to the tire-pass-through type X-ray apparatus 12.

[0030] The auxiliary storage device 34 stores various control programs, such as the tire wireless tag location inspection program 34A, and various data 34B. The CPU 22 reads the tire wireless tag location inspection program 34A from the auxiliary storage device 34, loads it into the RAM 26, and executes processing to detect the location of the RFID embedded in the tire T.

[0031] Next, the functional configuration of the processing unit 20 of the tire wireless tag position inspection device 10 according to this embodiment will be described. Figure 3 is a functional block diagram showing the functional configuration of the processing unit 20 of the tire wireless tag position inspection device 10 according to this embodiment.

[0032] In this embodiment, since X-ray imaging is performed from the side of tire T while it is being transported, the image of tire T becomes elliptical, and the position of the RFID is distorted. Therefore, in order to detect the angle along with the position of the RFID, it is necessary to make the elliptical shape closer to the actual shape. We want to image tire T as a perfect circle, but the image is distorted due to the frame rate of the imaging unit 16, the positional relationship between the imaging unit 16 and tire T, and the transport speed. The transport speed has a particularly large contribution; the imaging speed is constant, but if the transport speed is fast, the captured image becomes elliptical.

[0033] Therefore, the processing unit 20 extracts the bead on which the RFID is embedded from the captured image, calculates the ellipse equation by performing ellipse fitting, corrects the calculated ellipse to a perfect circle, and then performs a process to detect the position and angle of the RFID from the corrected captured image.

[0034] Specifically, the processing unit 20 functions as an acquisition unit 40, an extraction unit 42, a calculation unit 44, and a detection unit 46, as shown in Figure 3, by the CPU 22 executing a program stored in the ROM 24.

[0035] The acquisition unit 40 irradiates the tire T, which has an embedded RFID tag, with X-rays from the X-ray tube 14 while it is being transported, and acquires the X-ray image captured by the imaging unit 16.

[0036] The extraction unit 42 extracts a predetermined bead image from the captured image acquired by the acquisition unit 40. In this embodiment, since the tire is transported with the serial side facing upwards, the bead image of the serial side is extracted to facilitate RFID reading.

[0037] Since the RFID is located on the side of the upper bead of the tire T, in this case, position and angle assurance are based on the upper bead, and the extraction unit 42 extracts the upper bead from the captured image by extracting the inner bead that has been imaged.

[0038] In this embodiment, tires of different sizes, such as T, are rejected before imaging, so the positional relationship between the upper bead and the lower bead, as shown in Figure 4 as an example, is not distorted in the captured image. That is, in the captured image, the upper bead (solid line) is located inside the lower bead (dotted line) on the right side of Figure 4, and the lower bead (dotted line) is located inside the upper bead (solid line) on the left side of Figure 4.

[0039] When the upper and lower beads are imaged, as shown in Figure 5, both beads are captured in the image, and when the bead image is extracted, both the upper and lower beads are extracted. Normally, it is not possible to distinguish which is the upper bead and which is the lower bead. Therefore, for example, as shown in Figure 6, if the right end of the upper bead is constrained and the ellipse fitting process is started to fit it to a predetermined reference ellipse, it will gradually be pulled towards the lower bead, and in the upper and lower parts of the captured image in Figure 5, the reference ellipse may fit to the lower bead. We want to extract only the upper bead, but it is affected by the image of the lower bead. When upper and lower beads are mixed, it is not possible to extract an accurate ellipse shape, and the calculation unit 44 calculates an incorrect ellipse equation.

[0040] Therefore, as shown in Figure 7, the extraction unit 42 extracts only the upper bead by extracting an ellipse using edge extraction. In this embodiment, the upper bead is extracted, but the position of the RFID is determined by the type and size of the tire, and it may also be embedded in the lower bead. In this case, the lower bead may also be extracted. The position of the upper bead and the lower bead in the captured image are determined by the position and size of the X-ray tube 14 and the tire T, so this example is just one example.

[0041] The calculation unit 44 calculates an elliptic equation that matches the bead image extracted by the extraction unit 42 with a predetermined reference image. When calculating the elliptic equation, the calculation unit 44 significantly speeds up the process by utilizing the geometric properties of ellipses through well-known techniques to reduce and discretize parameters. The elliptic equation is calculated using the parameters ((xp) of the general elliptic equation. 2 / a 2 )+(yq) 2 ) / b 2 )=r 2 The equation initially consists of six parameters: a, b, and angle θ. However, based on the position of the captured tire T, these are reduced to four parameters. In this embodiment, due to the positional relationship between the imaging unit 16 and the tire T, the ellipse can only be distorted horizontally or vertically, so angle θ can be excluded. Furthermore, by dividing the entire equation by a, the parameters of the ellipse are reduced to a and b into one. Additionally, by discretization, the center of the ellipse can be found, which gives p and q.

[0042] The calculation unit 44 calculates the ellipse equation by reducing the number of parameters using techniques such as those described in the paper (Michele Fornaciari; "Very Fast Ellipse Detection for Embedded Vision Applications", Publisher: IEEE, ISBN: 978-1-4503-1772-6), as an example of well-known technology.

[0043] The detection unit 46 detects the position and angle of the RFID using the ellipse formula calculated by the calculation unit. In detail, the detection unit 46 includes a correction unit 48, an RFID detection unit 50, and a position and angle calculation unit 52.

[0044] The correction unit 48 corrects the ellipse to a perfect circle based on the ellipse equation calculated by the calculation unit 44. The correction is performed using the ratio of the major axis to the minor axis of the ellipse.

[0045] The RFID detection unit 50 detects the region containing the RFID from the captured image, which has been corrected to a perfect circle by the correction unit 48, as shown in Figure 8. Specifically, as shown in Figure 9, a predetermined reference RFID image 70 is prepared, and the unit searches for the area with the highest matching value by performing pattern matching with the reference RFID image 70. More specifically, as shown in Figure 9, the captured image, which has been corrected to a perfect circle by the correction unit 48, is converted into a strip-shaped image by polar coordinate transformation, and the RFID is searched for by pattern matching with the reference RFID image 70. The RFID search is performed by searching a predetermined inspection area, as shown in Figure 9.

[0046] The position angle calculation unit 52 calculates the position and inclination angle of the RFID detected by the RFID detection unit 50. The position angle calculation unit 52 uses the center of the circle formed by the bead image as a reference and calculates the circumferential position of the searched RFID and its inclination relative to the tangent to the reference circle. The radial position of the RFID can be estimated from the distance in the image by dividing the radius value in the image relative to the bead image by the radius value in the tire structure design of the tire bead member.

[0047] Next, we will describe the specific processing performed by the processing unit 20 of the tire wireless tag location inspection device 10 according to this embodiment. Figure 10 is a flowchart showing an example of the processing flow performed by the processing unit 20 of the tire wireless tag location inspection device 10 according to this embodiment. Note that the processing in Figure 10 starts, for example, when an instruction is given to start inspecting the RFID embedded in the tire.

[0048] In step 100, the CPU 22 irradiates the tire T with X-rays using the X-ray tube 14, starts imaging with the imaging unit 16, and proceeds to step 102.

[0049] In step 102, the CPU 22 acquires the captured image from the imaging unit 16 and proceeds to step 104. Specifically, the acquisition unit 40 acquires the X-ray image captured by the imaging unit 16 by irradiating the tire T, which has an RFID tag embedded in it, with X-rays from the X-ray tube 14 while the tire is being transported.

[0050] In step 104, the CPU 22 extracts the upper bead from the captured image and proceeds to step 106. That is, the extraction unit 42 extracts the upper bead image as a predetermined bead image from the captured image acquired by the acquisition unit 40.

[0051] In step 106, the CPU 22 calculates the ellipse formula of the upper bead and proceeds to step 108. Specifically, the calculation unit 44 calculates the ellipse formula that matches the bead image extracted by the extraction unit 42 with a predetermined reference image.

[0052] In step 108, the CPU 22 corrects the ellipse to a perfect circle and proceeds to step 110. That is, the correction unit 48 corrects the ellipse to a perfect circle based on the ratio of the major axis to the minor axis of the ellipse, using the ellipse equation calculated by the calculation unit 44.

[0053] In step 110, the CPU 22 detects the RFID from the captured image corrected to a perfect circle and proceeds to step 112. That is, the RFID detection unit 50 detects the region containing the RFID from the captured image corrected to a perfect circle by the correction unit 48, as shown in Figure 8. Specifically, as shown in Figure 9, a predetermined reference RFID image 70 is prepared, and the unit searches for a high-matching image by performing pattern matching with the reference RFID image 70.

[0054] In step 112, the CPU 22 calculates the position and angle of the RFID and proceeds to step 114. Specifically, the position and angle calculation unit 52 calculates the position and inclination angle of the RFID detected by the RFID detection unit 50. The position and angle are detected using the center of the circle formed by the bead image as a reference, and the circumferential position of the searched RFID and its inclination relative to the tangent to the reference circle are calculated. The radial position of the RFID is estimated from the distance in the image by dividing the radius value in the image relative to the bead image by the radius value in the tire structure design of the tire bead member.

[0055] In step 114, the CPU 22 determines whether or not there is another tire T. This determination determines whether or not the next tire T has been transported. If the determination is affirmative, the process returns to step 102 and the above process is repeated; if the determination is negative, the series of processes ends.

[0056] Traditionally, accurately imaging a tire T required a separate imaging device. For example, the bead would be fixed, a camera would be used to photograph the tire T from all directions, the distance between the bead and the RFID tag would be measured, and the tire T would be raised and rotated during transport for X-ray inspection. This method requires a separate device, which increases costs and installation space. Furthermore, raising the tire T for X-ray inspection is time-consuming.

[0057] In contrast, the tire wireless tag position inspection device 10 according to this embodiment does not require the incorporation of a separate device. It can detect the position of the RFID simply by imaging the tire T passing through the tire wireless tag position inspection device 10 and correcting the resulting ellipse to a perfect circle. Therefore, it is possible to save the cost and time required to detect the RFID, and the processing speed is also increased.

[0058] Furthermore, the tire wireless tag position inspection device 10 according to this embodiment can perform RFID inspection non-destructively. In addition, by performing the inspection during the idle time of the existing tire-passing type X-ray device 12, RFID inspection can be performed without reducing the processing capacity of the existing inspection line. Moreover, it is possible to add inspection functionality without adding a new inspection conveyor line.

[0059] In the above embodiment, an example was described using a tire-pass-through type X-ray apparatus 12 that uses a linear X-ray detector for imaging. However, the imaging unit 16 is not limited to a linear X-ray detector. For example, an imaging unit using an area-type X-ray detector may also be used.

[0060] Furthermore, the technical scope of this disclosure is not limited to the embodiments described above. Various modifications or improvements can be made to the embodiments without departing from the spirit, and such modified or improved forms are also included within the technical scope of this disclosure.

[0061] Furthermore, in the above embodiment, the process for estimating the movement of the wheelchair 12 was described in a case where it was implemented using a software configuration with a flowchart. However, the invention is not limited to this, and each process may be implemented using a hardware configuration, for example. [Explanation of Symbols]

[0062] 10 Tire wireless tag position inspection device, 12 Tire-through type X-ray device, 14 X-ray tube, 16 Imaging unit, 40 Acquisition unit, 42 Extraction unit, 44 Calculation unit, 46 Detection unit, 48 Correction unit, 50 RFID detection unit, 52 Position angle calculation unit, T Tire

Claims

1. Computers During the transport of a tire with a wireless tag embedded in it, X-rays are irradiated onto the tire to acquire an image. A predetermined bead image is extracted from the aforementioned captured image, From the extracted bead image, an ellipse equation matching a predetermined reference image is calculated. A tire wireless tag position inspection method that performs a process of detecting the position of the wireless tag using the calculated ellipse formula.

2. The tire wireless tag position inspection method according to claim 1, wherein the computer extracts the bead on the serial side as the predetermined bead.

3. The tire wireless tag position inspection method according to claim 1, wherein the computer calculates the ellipse formula by reducing the number of parameters in the ellipse formula.

4. The tire wireless tag position inspection method according to claim 3, wherein the computer calculates the ellipse formula using four parameters of the ellipse formula.

5. The tire wireless tag position inspection method according to claim 1, wherein the computer corrects the ellipse to a perfect circle and detects the position and angle of the wireless tag from the corrected perfect circle.

6. An acquisition unit that acquires an image by irradiating a tire with an embedded wireless tag with X-rays while the tire is being transported, An extraction unit extracts a predetermined bead image from the captured image acquired by the acquisition unit, A calculation unit calculates an elliptic equation that matches a predetermined reference image from the bead image extracted by the extraction unit, A detection unit that detects the position of the wireless tag using the ellipse formula calculated by the calculation unit, A tire wireless tag positioning device, including a tire wireless tag location inspection device.

7. On the computer, During the transport of a tire with a wireless tag embedded in it, X-rays are irradiated onto the tire to acquire an image. A predetermined bead image is extracted from the aforementioned captured image, From the extracted bead image, an ellipse equation matching a predetermined reference image is calculated. A tire wireless tag position inspection program that performs a process to detect the position of the wireless tag using the calculated ellipse formula.

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