Tire groove depth display method and tire groove depth display device

Abstract

The present invention provides a tire groove depth display method and a tire groove depth display device, which can improve the visibility of the partial wear state of the tire. The tire groove depth display method comprises: a contact part extraction step, a groove depth calculation step, an image generation step, and a display step. In the contact part extraction step, the contact part is extracted as a plurality of regions across the tire groove for the surface of the tread portion of the tire. In the groove depth calculation step, the depth of the tire groove between each region of the contact part is calculated. In the image generation step, an image is generated, which represents each region extracted by the contact part extraction step and information on the depth of the tire groove calculated by the groove depth calculation step. In the display step, the image generated by the image generation step is displayed.

Description

Technical Field

[0001] The invention relates to a tire groove depth display method and a tire groove depth display device. Background Art

[0002] Generally, tire wear develops according to driving conditions, driving distance, and the like. For example, when the tire pressure is low, the two sides of the tread are prone to wear, and when the tire pressure is high, the center of the tread is prone to wear. In addition, if the vehicle is parked in place or the vehicle is parked sideways, the tire is prone to wear on the outer side of the front axle. In addition, there are many factors that lead to uneven tire wear, such as the vehicle's driving method, driving style, weight balance, rapid acceleration and deceleration, and sharp turns. Therefore, for the tires installed on the vehicle, the four wheels wear unevenly, and even within one tire, the wear may develop irregularly or locally.

[0003] Patent document 1 describes a method for generating a three-dimensional phase geometry surface display of a vehicle tire. This prior art method uses a tread depth measuring device, records tread depth data of a tire surface that moves relative to the tread depth measuring device, and uses the movement profile of the tire surface to map the tread depth data onto a basic tire structure to generate a three-dimensional phase geometry surface display of the tire.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application No. 2019-518209 Summary of the invention

[0007] 1. Technical issues to be resolved

[0008] The method of generating a three-dimensional phase geometric surface display described in Patent Document 1 generates a geometric display of the tire, but only displays the surface shape of the tire, which makes it difficult for the operator to understand the uneven wear state of the tire.

[0009] The present invention has been made in view of the above situation, and an object thereof is to provide a tire groove depth display method and a tire groove depth display device that can improve the visibility of the uneven wear state of the tire.

[0010] (II) Technical solution

[0011] One embodiment of the present invention is a tire groove depth display method. The tire groove depth display method comprises: a contact portion extraction step of extracting the contact portion as a plurality of regions across the tire groove on the surface of the tire tread; a groove depth calculation step of calculating the depth of the tire groove between the regions of the contact portion; an image generation step of generating an image representing information on the regions extracted by the contact portion extraction step and the depth of the tire groove calculated by the groove depth calculation step; and a display step of displaying the image generated by the image generation step.

[0012] Another embodiment of the present invention is a tire groove depth display device. The tire groove depth display device comprises: a contact part extraction unit that extracts the contact part as a plurality of regions across the tire groove from the surface of the tire tread; a groove depth calculation unit that calculates the depth of the tire groove between the regions of the contact part; an image generation unit that generates an image that represents the regions extracted by the contact part extraction unit and the information of the depth of the tire groove calculated by the groove depth calculation unit; and a display unit that displays the image generated by the image generation unit.

[0013] (III) Beneficial effects

[0014] According to the present invention, the visibility of the uneven wear state of the tire can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 1 is a block diagram showing a configuration of a tire sipe measurement system including the tire sipe display device according to the embodiment.

[0016] Figure 2 It is a schematic diagram for explaining measurement by a scanning device.

[0017] Figure 3 It is a schematic diagram showing the three-dimensional coordinate data acquired by the data acquisition unit.

[0018] Figure 4 This is a schematic diagram for explaining the removal of point groups by the ground portion extraction unit.

[0019] Figure 5 This is a schematic diagram for explaining the ground portion extraction performed by the ground portion extraction unit.

[0020] Figure 6 is a schematic diagram for explaining the envelope region created by the groove depth calculation unit.

[0021] Figure 7 It is a schematic diagram for explaining the creation of a three-dimensional region by the groove depth calculation unit.

[0022] Figure 8This is a flowchart showing the tire groove depth display processing procedure.

[0023] Fig. 9 1 is a schematic diagram showing an example of image display by a tire groove depth display device.

[0024] Fig.10 FIG. 1 is a schematic diagram showing another example of image display by the tire groove depth display device.

[0025] Fig.11 (a) and (b) are schematic diagrams showing still another example of image display by the tire groove depth display device.

[0026] Fig.12 This is a schematic diagram for explaining a method of extracting a contact patch and calculating a tire groove depth by moving each point.

[0027] Description of Reference Numerals

[0028] 40a: ground contact part extraction unit; 40c: groove depth calculation unit; 40d: image generation unit; 50: display unit; 9: tire; 9a: tread portion; 90: surface; 90a: tire groove; 91: ground contact part; 10: tire groove depth display device. DETAILED DESCRIPTION

[0029] Below, based on the preferred embodiment and referring to Figures 1 to 12 The present invention is described. The same or equivalent components and parts shown in each figure are marked with the same reference numerals, and repeated descriptions are appropriately omitted. In addition, the sizes of the parts in each figure are appropriately enlarged or reduced for easy understanding. In addition, some parts that are not important for explaining the implementation method are omitted in each figure.

[0030] (Implementation Method)

[0031] Figure 1 1 is a block diagram showing the structure of a tire groove measurement system 100 including a tire groove depth display device 10 according to an embodiment. The tire groove measurement system 100 includes the tire groove depth display device 10 and a scanning device 6. The tire groove measurement system 100 measures image data and three-dimensional coordinate data of a surface 90 of a tread portion 9a of a tire 9 mounted on a vehicle by means of the scanning device 6, and calculates and displays the depth of a tire groove 90a by means of the tire groove depth display device 10. The tire groove 90a is formed, for example, to extend in the tire circumferential direction.

[0032] Figure 2Schematic diagram for explaining measurement by the scanning device 6. The scanning device 6, for example, photographs the surface 90 of the tread portion 9a of the tire 9, and measures the three-dimensional coordinate data of the point group on the surface 90 based on the principle of a stereo camera. The scanning device 6 obtains the three-dimensional coordinate data of the point group on the surface of the ground contact portion 91 in contact with the road surface and the bottom 92 of the tire groove 90a with respect to the surface 90 of the tread portion 9a.

[0033] In the measurement based on the principle of a stereo camera, for example, a pattern for measurement is optically projected onto the surface 90 of the tread portion 9a, and three-dimensional coordinate data of a group of points on the surface 90 are obtained based on data obtained by capturing the surface 90 by two capturing units (not shown). As for the method of measuring the three-dimensional coordinate data of the surface 90 of the tread portion 9a in the scanning device 6, a known technique such as distance measurement based on the principle of a stereo camera can be used.

[0034] The scanning device 6 acquires the three-dimensional coordinate data of a group of points on the surface 90 in an orthogonal coordinate system determined by the device itself. Figure 2 As shown, the scanning device 6 acquires the three-dimensional coordinate data of the point group in the orthogonal coordinate system with the tire radial direction as the Z-axis direction, the tire circumferential direction as the X-axis direction, and the tire axial direction (tire width direction) as the Y-axis. In addition, the scanning device 6 may also measure the coordinate data of the point group in a local coordinate system based on the front direction toward the measurement object and two axes orthogonal thereto, and perform coordinate conversion to the above-mentioned (X, Y, Z) coordinate system in the scanning device 6 or in the tire groove depth display device 10 at the subsequent stage.

[0035] return Figure 1 The tire groove depth display device 10 includes a data acquisition unit 20, a storage unit 30, a tire image processing unit 40, and a display unit 50. Each unit in the tire groove depth display device 10 can be implemented in hardware by electronic components represented by a CPU of a computer, mechanical components, etc., and can be implemented in software by computer programs, etc., and the functional blocks implemented by the above-mentioned cooperation are described here. Therefore, those skilled in the art can know that these functional blocks can be implemented in various ways by combining hardware and software.

[0036] The data acquisition unit 20 acquires the three-dimensional coordinate data of the point group on the surface 90 of the tread portion 9a from the scanning device 6, and stores it in the storage unit 30. The storage unit 30 is a storage device composed of, for example, an SSD (Solid State Drive), a hard disk, a RAM (Random Access Memory), etc. The display unit 50 is a display device such as a liquid crystal display, which displays an image showing each area of ​​the contact portion 91 and the depth of the tire groove 90a.

[0037] The tire image processing unit 40 includes a land portion extraction unit 40 a , a region division unit 40 b , a groove depth calculation unit 40 c , and an image generation unit 40 d .

[0038] Figure 3 is a schematic diagram showing the three-dimensional coordinate data acquired by the data acquisition unit 20. Figure 3 In FIG. 1 , a part of the surface 90 of the tire 9 is represented by a simplified model. Based on this model, the following describes the process of extracting the land portion 91 and calculating the groove depth of the tire 9 .

[0039] exist Figure 3 In the above, the three-dimensional coordinate data of the point group acquired by the data acquisition unit 20 is data in the (X, Y, Z) coordinate system, and includes data of the contact portion 91, the bottom 92 of the sipe 90a, and the side portion 93. The contact portion extraction unit 40a calculates the surface normal vector of each point based on the three-dimensional coordinate data of the point group on the surface 90.

[0040] Figure 4 Schematic diagram for explaining the removal of point groups by the land portion extraction unit 40a. Among the point groups on the surface 90, the point group of the side surface 93 of the sipe 90a is removed by the land portion extraction unit 40a because the normal vector is substantially orthogonal to the Z axis.

[0041] The ground portion extraction unit 40 a extracts a plurality of ground portions 91 based on the three-dimensional coordinate data and normal vectors of the point group. Figure 5 This is a schematic diagram for explaining the extraction of the ground portion 91 by the ground portion extraction unit 40a. The ground portion extraction unit 40a identifies a group of points having certain continuity characteristics such as normal vectors being in substantially the same direction as a cluster (group) belonging to the same surface. This cluster identification can be performed using a known method.

[0042] The width of the tire groove 90a is generally narrower than the width of the land portion 91, so the clusters with narrower widths among the identified clusters are regarded as not constituting the land portion 91, and the remaining clusters are regarded as the land portion 91. Figure 5 As shown, the land portion extracting unit 40a extracts the region A and the region B constituting the land portion 91 across the sipe 90a. When a plurality of sipes 90a are arranged in the tire width direction, the land portion extracting unit 40a extracts a plurality of regions across each sipe 90a.

[0043] The region division unit 40b divides each region of the land portion 91 extracted by the land portion extraction unit 40a along the tire circumferential direction to generate a tire width direction region. Figure 5 As shown, the area dividing portion 40b divides the plurality of land portions 91 by straight lines L1 and L2 extending in the tire width direction. The area dividing portion 40b is divided equally into sections, for example, with a length of less than 5 cm along the tire circumferential direction. Figure 6 Only a portion is shown, but the system is actually divided into many regions.

[0044] Figure 6 4 is a schematic diagram for explaining the envelope domain generated by the groove depth calculation unit 40c. Figure 6 In one tire width direction region sandwiched between the straight line L1 and the straight line L2, the region A and the region B as the land portion 91 are adjacent to each other, and the groove depth calculation unit 40c generates a region C between the region A and the region B as an envelope region.

[0045] The region C as the envelope domain is a polygonal region surrounded by the sides of the regions A and B facing each other and the straight lines L1 and L2. The envelope domain is a region between the land portions 91 and is a region where basically no point group exists. For example, the groove depth calculation unit 40c generates a plurality of land portion envelope domains based on a concave envelope or a convex envelope for each of the plurality of land portions 91 in the tire width direction region, and sets the region excluding each land portion envelope domain from the tire width direction region as the envelope domain.

[0046] Since the surface 90 of the tread portion 9a is a curved surface, each of the regions A, B, and C is also a curved surface. However, if each region is subdivided to a degree that can approximate a flat surface without curvature, the calculation can be simplified. Specifically, when setting the tire width direction region, by dividing it along the tire circumferential direction at intervals of about 40 mm, each region can be treated as a flat surface in most tires.

[0047] Figure 7 1 is a schematic diagram for explaining the creation of a three-dimensional region by the groove depth calculation unit 40c. The groove depth calculation unit 40c uses the envelope region, that is, the region C, as a base, and sets the direction intersecting the base, for example, the normal direction of the base, as the height direction to create a columnar three-dimensional region V having a predetermined size in the height direction. The predetermined size is, for example, set to a value greater than the depth of the main groove in the tire specification.

[0048] The groove depth calculation unit 40c extracts the point group included in the three-dimensional area V as the point group of the bottom 92 of the tire groove 90a. The groove depth calculation unit 40c calculates the groove depth of the tire 9 by calculating the distance from the base to the point group included in the three-dimensional area V.

[0049] The groove depth calculation unit 40c generates a distribution of the distances of the point group from the base, and calculates the median value, the 95th percentile value, etc. as the groove depth. As for the area C as the base, by approximating it with a plane as described above, it is easy to calculate the distance between the point group of the bottom of the tire groove included in the three-dimensional area V and the area C in the direction intersecting the area (normal direction).

[0050] The image generator 40d generates an image showing each area extracted by the land portion extractor 40a and information on the depth of the tire sipe 90a calculated by the sipe depth calculator 40c, and outputs the image to the display 50. The display 50 displays the image input from the image generator 40d.

[0051] When the area dividing unit 40b divides the land portion 91 into respective areas along the tire circumferential direction, the image generating unit 40d generates an image including a figure (eg, Figure 5 straight line L1 and straight line L2, etc. shown).

[0052] When the groove depth calculation unit 40c calculates the depth of the tire groove 90a for each tire width direction region, the image generation unit 40d generates an image showing information on the depth calculated for each tire width direction region.

[0053] Next, the operation of the tire groove depth display device 10 will be described. Figure 8 1 is a flowchart showing the display processing sequence of the tire groove depth. Before the display processing of the tire groove depth starts, the scanning device 6 captures the surface 90 of the tread portion 9a of the tire 9 and measures the three-dimensional coordinate data of the point group on the surface 90. The data acquisition unit 20 of the tire groove depth display device 10 acquires the three-dimensional coordinate data of the point group on the surface 90 of the tread portion 9a from the scanning device 6 (S1).

[0054] The land portion extraction unit 40a of the tire image processing unit 40 extracts the land portion 91 as a plurality of regions across the tire groove 90a based on the three-dimensional coordinate data of the point group on the surface 90 (S2). The region segmentation unit 40b segments each region of the land portion 91 extracted by the land portion extraction unit 40a along the tire circumferential direction to generate tire width direction regions (S3).

[0055] The groove depth calculation unit 40c calculates the depth of the tire groove 90a between each region (S4). The image generation unit 40d generates an image showing each region of the contact portion 91 and information on the depth of the tire groove 90a calculated by the groove depth calculation unit 40c, and outputs it to the display unit 50 (S5). The display unit 50 displays the image input from the image generation unit 40d (S6), and the process ends.

[0056] Fig. 9 FIG. 1 is a schematic diagram showing an example of an image display by the tire groove depth display device 10. Fig. 9In the image display shown, each area of ​​the land portion 91 is not divided in the tire circumferential direction, but each area of ​​the land portion 91 separated by the tire groove 90a and information (numerical value) of the depth of the tire groove 90a are displayed. The tire groove depth display device 10 can improve the visibility of the uneven wear state of the tire 9 in the tire width direction by displaying the information of each area of ​​the land portion 91 and the depth of the tire groove 90a.

[0057] Fig.10 FIG. 2 is a schematic diagram showing another example of image display by the tire groove depth display device 10. Fig.10 The image display shown includes depth information of the tire groove 90a related to the tire width direction area obtained by dividing each area of ​​the contact portion 91. The tire groove depth display device 10 can improve the visibility of the uneven wear state of the tire 9 in the tire width direction and the tire circumferential direction by displaying the information of the depth of the tire groove 90a related to each area of ​​the contact portion 91 and a plurality of tire width direction areas.

[0058] Fig.11 (a) and (b) are schematic diagrams showing another example of image display based on the tire groove depth display device 10. Fig.11 In the image display shown in (a) of FIG. 1 , the tire width direction area is represented by a line segment. Fig.11 In the image display shown in (b), the tire width direction area is represented by pattern or color. The tire groove depth display device 10 can make the operator more clearly know the area of ​​the land portion 91 corresponding to the depth information of the tire groove 90a by clearly indicating the division of the tire width direction area.

[0059] In the above embodiment, the method of extracting the land portion 91 and the method of calculating the depth of the tire groove 90a using the envelope domain and the three-dimensional area are shown, but the method of extracting the land portion 91 and calculating the groove depth are not limited to these.

[0060] Fig.12 Schematic diagram for explaining a method of extracting the contact portion 91 and calculating the depth of the tire groove 90a by moving each point. The position of each point on the surface 90 of the tire 9 is calculated by moving it in the direction of the normal vector, for example, and finding the nearest neighboring point before and after the point is moved. Fig.12 For point P1 included in the ground portion 91 shown, the nearest neighbor point before and after the movement is found to be the same point P2 included in the ground portion 91. Also, for point P3 included in the bottom portion 92, the nearest neighbor point before the movement is found to be P4, and the nearest neighbor point after the movement is found to be point P2.

[0061] When the calculated nearest neighboring points before and after the movement are the same, it is determined to be a point in the ground portion 91, and if the nearest neighboring points are different, it is determined to be a point in the bottom portion 92. After determining whether each point on the surface 90 of the tire 9 belongs to the ground portion 91 or the bottom portion 92, the Z-direction heights of the ground portion 91 and the bottom portion 92 are obtained, and the depth of the tire groove 90a is calculated.

[0062] Alternatively, the ground portion 91 and the sipe 90a may be identified in the image obtained by photographing the surface 90 of the tire 9 to extract the ground portion 91. Alternatively, the ground portion 91 may be extracted and the depth of the sipe 90a may be calculated by scanning the surface of the tire 9 using a laser or millimeter wave distance measuring device.

[0063] Next, features of the tire groove depth display device 10 and the tire groove depth display method according to the embodiment will be described.

[0064] The tire groove depth display method of the embodiment comprises: a contact part extraction step, a groove depth calculation step, an image generation step, and a display step. In the contact part extraction step, the contact part 91 is extracted as a plurality of regions with the tire groove 90a interposed therebetween for the surface 90 of the tread portion 9a of the tire 9. In the groove depth calculation step, the depth of the tire groove 90a between each region of the contact part 91 is calculated. In the image generation step, an image is generated, which represents each region extracted by the contact part extraction step and information on the depth of the tire groove 90a calculated by the groove depth calculation step. In the display step, the image generated by the image generation step is displayed. According to the tire groove depth display method, by displaying information on each region of the contact part 91 and the depth of the tire groove 90a, the visibility of the uneven wear state of the tire 9 in the tire width direction can be improved.

[0065] The tire groove depth display method further includes a region segmentation step, in which each region extracted by the contact part extraction step is segmented along the tire circumferential direction to generate a tire width direction region. In the groove depth calculation step, the depth of the tire groove 90a is calculated for each tire width direction region. In the image generation step, an image is generated, which represents the information of the depth of the tire groove 90a calculated by the groove depth calculation step for each tire width direction region. According to the tire groove depth display method, by displaying the information of the depth of the tire groove 90a related to each region of the contact part 91 and a plurality of tire width direction regions, it is possible to improve the visibility of the uneven wear state of the tire 9 in the tire width direction and the tire circumferential direction.

[0066] In the image generation step, an image is generated by dividing the tire width direction region and displaying it. According to this tire sipe depth display method, the operator can more clearly know the region of the land portion 91 corresponding to the depth information of the tire sipe 90a.

[0067] The tire groove depth display device 10 includes: a contact part extraction unit 40a, a groove depth calculation unit 40c, an image generation unit 40d, and a display unit 50. The contact part extraction unit 40a extracts the contact part 91 as a plurality of regions with the tire groove 90a interposed therebetween from the surface 90 of the tread portion 9a of the tire 9. The groove depth calculation unit 40c calculates the depth of the tire groove 90a between each region of the contact part 91. The image generation unit 40d generates an image, which represents each region extracted by the contact part extraction unit 40a and information on the depth of the tire groove 90a calculated by the groove depth calculation unit 40c. The display unit 50 displays the image generated by the image generation unit 40d. Thus, the tire groove depth display device 10 can improve the visibility of the uneven wear state of the tire 9 in the tire width direction by displaying information on each region of the contact part 91 and the depth of the tire groove 90a.

[0068] The above is described based on the embodiments of the present invention. These embodiments are only for illustration, and for those skilled in the art, various modifications and changes can be made within the scope of the claims of the present invention, and such modifications and changes also belong to the scope of the claims of the present invention. Therefore, the descriptions and drawings in this specification are not for limitation, but for illustration.

Claims

1. A tire groove depth display method, comprising the following steps: A contact part extraction step, extracting the contact part as a plurality of regions from the surface of the tread portion of the tire through the tire grooves; A groove depth calculation step, calculating the depth of the tire groove between the areas of the contact portion; An image generating step of generating an image representing each area extracted by the contact portion extracting step and information on the depth of the tire groove calculated by the groove depth calculating step; as well as a display step of displaying the image generated by the image generating step, The contact portion extraction step removes the side surface portion of the tire groove based on the normal vector of the side surface portion being orthogonal to the tire radial direction.

2. The tire groove depth display method according to claim 1, characterized in that: The method further comprises a region division step of dividing each region extracted in the land portion extraction step in the tire circumferential direction to generate a tire width direction region. In the groove depth calculation step, the depth of the tire groove is calculated for each of the tire width direction regions. In the image generating step, an image is generated which indicates information on the depth of the tire groove calculated for each of the tire width direction regions in the groove depth calculating step.

3. The tire groove depth display method according to claim 2, characterized in that: In the image generating step, an image is generated by dividing the tire width direction region and displaying the divided region.

4. A tire groove depth display device, comprising: A contact portion extraction unit extracts the contact portion as a plurality of regions on the surface of the tread portion of the tire via the tire grooves; a groove depth calculation unit for calculating the depth of the tire groove between the areas of the contact portion; an image generating unit configured to generate an image representing each area extracted by the contact portion extracting unit and information on the depth of the tire groove calculated by the groove depth calculating unit; as well as a display unit that displays the image generated by the image generating unit, The land portion extraction unit removes the side surface portion of the tire sipe based on the normal vector of the side surface portion being orthogonal to the tire radial direction.

Images