KR101412480B1 - A method of measuring full and shawl width of tread of tire - Google Patents

A method of measuring full and shawl width of tread of tire Download PDF

Info

Publication number
KR101412480B1
KR101412480B1 KR1020140019074A KR20140019074A KR101412480B1 KR 101412480 B1 KR101412480 B1 KR 101412480B1 KR 1020140019074 A KR1020140019074 A KR 1020140019074A KR 20140019074 A KR20140019074 A KR 20140019074A KR 101412480 B1 KR101412480 B1 KR 101412480B1
Authority
KR
South Korea
Prior art keywords
tread
coordinates
width
opt
shoulder
Prior art date
Application number
KR1020140019074A
Other languages
Korean (ko)
Inventor
문기승
Original Assignee
대하테크원(주)
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 대하테크원(주) filed Critical 대하테크원(주)
Priority to KR1020140019074A priority Critical patent/KR101412480B1/en
Application granted granted Critical
Publication of KR101412480B1 publication Critical patent/KR101412480B1/en

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C25/00—Apparatus or tools adapted for mounting, removing or inspecting tyres
    • B60C25/002—Inspecting tyres
    • B60C25/007—Inspecting tyres outside surface
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/04—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness specially adapted for measuring length or width of objects while moving
    • G01B11/046—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness specially adapted for measuring length or width of objects while moving for measuring width
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M17/00—Testing of vehicles
    • G01M17/007—Wheeled or endless-tracked vehicles
    • G01M17/02—Tyres
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
    • G01N21/956—Inspecting patterns on the surface of objects
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/0002—Inspection of images, e.g. flaw detection
    • G06T7/0004—Industrial image inspection
    • G06T7/001—Industrial image inspection using an image reference approach

Abstract

The present invention relates to a tread width measuring method for measuring a tread width and a width of a tread in a tread using a camera and a laser, Extracting jig coordinates from the photographed jig image to perform calibration, extracting a lens distortion coefficient of the camera using the jig coordinates, and a conversion function (H) between the camera plane and the laser plane; Obtaining an input image (B) of the tread region irradiated with the laser light, calculating N threshold values using the brightness distribution of the input image, calculating an optimal threshold value for the tread contour extraction among the N threshold values (thr opt ); A thresholded image C opt or a skeleton coordinate P opt is obtained by applying the optimal threshold value thr opt to the input image and the end coordinates of the tread using the skeletal coordinates P opt E opt ) and a shoulder coordinate (S opt ); And the end coordinate (E opt ) and the shoulder coordinate (S opt ) obtained by correcting the lens distortion using the lens distortion correction model

Figure 112014016263849-pat00030
) And shoulder coordinates (
Figure 112014016263849-pat00031
Calculating actual distance coordinates (E real , S real ) using the transform function, and calculating the full width and the sull width of the tread using the actual distance coordinates. Therefore, the present invention can precisely and precisely measure the full width and the width of the tread, thereby significantly reducing the error range of the full width of the tread and improving the quality of the entire tire by automatically managing the tread width that determines the actual tire quality In addition, the filtering process using the moving average for correcting the lens distortion or the abnormal point can correct the distortion and measure the noise-canceled full width and the sharpness.

Description

[0001] METHOD OF MEASURING FULL AND SHAWL WIDTH OF TREAD OF TIRE [0002]

The present invention relates to a tread width measuring method and, more particularly, to a tread width measuring method capable of accurately and precisely measuring a full width and a width of a tread by performing a calibration algorithm and a width measuring algorithm.

BACKGROUND ART [0002] Conventionally, in the production of a tire, the surface shape of a tire is inspected in a shape inspection after a vulcanization process, which is a final process. In recent years, tire surface shape inspection has been automated using a laser light source and a shape measuring apparatus including a sensor unit using a CCD camera or a CMOS camera for taking an image by the laser light.

In the shape inspection using the laser light by the tire surface shape measuring apparatus, sheet-like laser light (line light) is irradiated on the tread surface or sidewall surface of the tire to form a light cut line on the surface. Thereafter, the optical cutting line is photographed by a photographing means such as a CCD camera or a CMOS camera, and the optical cutting method is applied to the photocutting line so that the three-dimensional shape of the tire surface is measured and inspected.

For example, in the measurement of the three-dimensional shape of the side wall surface, the fine irregularities on the side wall surface are accurately detected and inspected by removing the normal irregular shape caused by characters, logo marks and the like from the three-dimensional shape thus obtained.

In recent years, treads for passenger cars have been made wider in width than tires in the prior art, and the sidewalls have become thinner. That is, the development is proceeding in the direction in which the difference between the width of the tread surface and the thickness of the side wall surface is increased. Further, the development of the tire size is spread over many surfaces, and the size and shape of the tire to which the shape measuring apparatus should respond are increasing.

As a prior art document, Korean Patent No. 10-0426143 discloses a description of a device for measuring the shape and depth of a portable tire tread.

A conventional portable tire tread shape and depth measuring apparatus is a device for measuring the shape and depth of a tire by rotating a tire at a constant speed and placing a sensor capable of moving in a tread width direction above the tire tread, storing sensed data of the sensor in a computer, And measures the wear and shape of the tread according to the distance traveled, thereby preventing a measurement deviation. Even when the tread is worn out, it is not affected by the measurement. Can be measured in a short time.

However, in the conventional portable tire tread shape and depth measuring device, there is a problem that the driver has to manually operate the device installed in the tire from the outside of the vehicle.

Korean Patent Laid-Open No. 2005-0094211 discloses a tire tread width measuring apparatus. In order to measure a length of a shoulder width (SW) of a tread using a camera, an illuminating unit for illuminating both sides of the tread is provided And a conveying screw for guiding the conveying motor and the guide bar.

In such a conventional tread swell width measuring apparatus, when the light irradiated from the illumination unit is reflected on the inclined surface of the tread, a light quantity distortion occurs, and precise measurement of the swell width still becomes a problem. On the other hand, in order to reduce distortion of light quantity, a high-resolution camera and an additional means for correcting it are required. When using a high-resolution camera, the price of the tread shoelace measuring equipment is increased, and the correction means has to be checked each time by a human worker in order to secure the accuracy.

Therefore, in the future, in order to reduce the error range of the measurement at a low cost, a new measurement algorithm with reliable reliability is required.

Korean Patent Publication No. 2005-0094211 "Tire Tread Width Measuring Apparatus" Korean Patent No. 0426143 entitled " Device for Measuring Shape and Depth of Portable Tread "

The present invention measures a full width and a width of a tread by measuring a full width and a width of a tread by performing a calibration algorithm and a width measurement algorithm and corrects distortion by filtering processing using a moving average for lens distortion correction or an ideal point elimination, And a method of measuring the tread width and the shoulps which can measure the shoulps.

Among the embodiments, the method of measuring the tread width and the shoelace width is a method of measuring a tread width, which is performed by a tread measuring apparatus that measures a sled width and a full width at a tread using a camera and a laser, Extracting a jig coordinate from a jig image to perform calibration, extracting a lens distortion coefficient of the camera using the jig coordinate, a conversion function (H) between the camera plane and the laser plane, Obtaining an input image (B) of the tread region irradiated with the laser light, calculating N threshold values using the brightness distribution of the input image, calculating an optimal threshold value for the tread contour extraction among the N threshold values (thr opt ); A thresholded image C opt or a skeleton coordinate P opt is obtained by applying the optimal threshold value thr opt to the input image and the end coordinates of the tread using the skeletal coordinates P opt E opt ) and a shoulder coordinate (S opt ); And the end coordinate (E opt ) and the shoulder coordinate (S opt ) obtained by correcting the lens distortion using the lens distortion correction model

Figure 112014016263849-pat00001
) And shoulder coordinates (
Figure 112014016263849-pat00002
Calculating actual distance coordinates (E real , S real ) using the transform function, and calculating the full width and the sull width of the tread using the actual distance coordinates.

Wherein the step of calculating the full width and the width of the tread using the actual distance coordinates comprises:

Figure 112014016263849-pat00003
) And shoulder coordinates (
Figure 112014016263849-pat00004
) Is calculated by performing a moving average operation such that an outlier out of the standard deviation or more is removed by using the end coordinates and the shoulder coordinates of the previous end,
Figure 112014016263849-pat00005
) And average shoulder (
Figure 112014016263849-pat00006
) Coordinates; Applying the average end coordinate and the average shoulder coordinate to the transform function to output a final end coordinate (E out ) and a final shoulder coordinate (S out ); And computing the full width and shoulder width of the tread using the final end coordinates and the final shoulder coordinates.

Wherein calculating the full width and shoulder width of the tread using the final end coordinates and the final shoulder coordinates is performed such that the final end coordinates and the final shoulder coordinates are each made up of pairs of left and right coordinates, And calculates the total width of the tread and the shoulder width by calculating the distance.

The step of performing the calibration may include detecting the coordinates of the vertices of each jig in the jig image, searching the line coordinates having the maximum brightness value and the maximum sharpness, and performing the calibration using the intersection of the lines.

Wherein the step of calculating N threshold values using the brightness distribution of the input image and determining the optimal threshold value thr opt for extracting tread contour from the N threshold values comprises: Calculating an average and a standard deviation, and determining a minimum threshold and a maximum threshold based on the calculated average and the standard deviation; Dividing the range of the threshold value into (N-1) intervals and calculating the N threshold values; Thresholding and binarizing the input image with the N threshold values to obtain an image C i for each threshold value and extracting a maximum region of the image C i as a tread region T i step; Extracting tread left and right end coordinates (E i ) and shoulder left and right coordinates (S i ) with respect to the skeleton (P i ) by applying a thinning algorithm to the tread region (T i ); And a step of measuring a left-right symmetry degree by using the tread left and right end coordinates (E i ) and a shoulder left and right coordinates (S i ), and determining the threshold value having the greatest right-left symmetry degree as an optimum threshold value thr opt .

The method of measuring the tread width and the shoulps width of the present invention can significantly reduce the error range of the full width of the measured tread by measuring the full width and the width of the tread accurately and precisely by performing the calibration algorithm and the width measurement algorithm, It is possible to improve the quality of the whole tire by automatically managing the width of the tread. In addition, the distortion is corrected by the filtering process using the moving average for correction of the lens distortion or the abnormal point, and the width and the width of the noise are removed There is an effect that can be done.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view for explaining a menu screen output from a tread measuring apparatus for performing a tread width and a tread width measuring method according to an embodiment of the present invention; FIG.
2 is a flowchart illustrating a method of measuring a tread width and a shovel width according to an embodiment of the present invention.
3 is a view for explaining a shape of an outline that can be obtained by a jig image;
4 is a view for explaining a selection window for calibration;
5 is a view for explaining a configuration of a tread measuring apparatus to which a general optical cutting method is applied;
6 is a view for explaining a method of extracting left and right coordinates of a shoulder;
7 is a view for explaining a screen for displaying a tread width measured by a tread full width and a torn width measuring method according to an embodiment of the present invention;

The description of the present invention is merely an example for structural or functional explanation, and the scope of the present invention should not be construed as being limited by the embodiments described in the text. That is, the embodiments are to be construed as being variously embodied and having various forms, so that the scope of the present invention should be understood to include equivalents capable of realizing technical ideas. Also, the purpose or effect of the present invention should not be construed as limiting the scope of the present invention, since it does not mean that a specific embodiment should include all or only such effect.

Meanwhile, the meaning of the terms described in the present invention should be understood as follows.

The terms "first "," second ", and the like are intended to distinguish one element from another, and the scope of the right should not be limited by these terms. For example, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

It is to be understood that when an element is referred to as being "connected" to another element, it may be directly connected to the other element, but there may be other elements in between. On the other hand, when an element is referred to as being "directly connected" to another element, it should be understood that there are no other elements in between. On the other hand, other expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

It should be understood that the singular " include "or" have "are to be construed as including a stated feature, number, step, operation, component, It is to be understood that the combination is intended to specify that it does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

In each step, the identification code (e.g., a, b, c, etc.) is used for convenience of explanation, the identification code does not describe the order of each step, Unless otherwise stated, it may occur differently from the stated order. That is, each step may occur in the same order as described, may be performed substantially concurrently, or may be performed in reverse order.

All terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Commonly used predefined terms should be interpreted to be consistent with the meanings in the context of the related art and can not be interpreted as having ideal or overly formal meaning unless explicitly defined in the present invention.

FIG. 1 is a view for explaining a menu screen output from a tread measuring apparatus for performing a tread width measuring method and a tread width measuring method according to an embodiment of the present invention.

As shown in FIG. 1, a tread measuring apparatus including a camera and a laser continuously measures a tread width and a sled width, and outputs the measured results to a screen. To this end, the tread measuring device sequentially performs a calibration algorithm and a width measurement algorithm.

Such a tread measuring device displays the tread extracted from the input image in real time, shows the full width and the shoelength obtained by extracting the tread weight, and successively indicates whether the full width and the shoelength of the tread have been successfully measured.

For example, the tread measuring device is 'ON' in green when it is successful in tread detection, and 'OFF' in red when there is no tread or detection fails.

Further, the tread measuring apparatus is turned on when the socket communication with the PLC operates normally, and is turned off when the communication is impossible.

The tread measuring apparatus provides continuous shooting, that is, a moving picture, through a grab menu so that the manager can check the position of the jig or the shooting area of the current image. Further, the tread measuring apparatus stores the image as a file through the capture menu, and performs a photographing function to store the image file captured in the capture folder.

The tread measuring apparatus executes a camera control program between a frame grabber and a camera, adjusts a camera use area (ROI) through a camera control program, corrects a frame rate, an analog / digital gain, When the set values are changed, the brightness value of the input image and the thickness of the laser light may be changed.

If the set value is improperly set by the administrator, the intensity of the laser light may be weak and the line width may be cut off or the intensity of the laser light may be too high to detect the exact width of the tread.

FIG. 2 is a flowchart for explaining a method of measuring a tread width and a shovel width according to an embodiment of the present invention. FIG. 3 is a view for explaining a shape of a contour obtained by a jig image, FIG.

Referring to FIGS. 2 to 5, the tread width and the shoelace width measurement method photographs a jig installed at a predetermined position using a camera, and extracts jig coordinates for a vertex and a line from the captured jig image to perform calibration. (S1, S2)

The relationship between the camera and the laser is determined before measuring the tread width and the swollenness. The calibration data obtained by the calibration is fixed data that is not changed. The password is set so that a third party other than the manager can not access the calibration data do.

If the position change of the camera and the laser occurs, new calibration data must be obtained, a jig for calibrating is installed, and the jig is arranged at a proper position so that the juxtaposition line of the jig appears as a plurality of serrations.

As shown in FIG. 3, the tread measuring apparatus detects vertex coordinates of each jig in a jig image captured by a frame grabber, finds line coordinates having the maximum brightness and maximum sharpness, and performs calibration using the intersection of the lines (S3)

As shown in FIG. 4, the tread measuring apparatus outputs a selection window for calibration to a screen, and a threshold value can be set by the manager so that only the outlines of the jig can appear as clearly as possible.

The tread measuring apparatus extracts the lens distortion coefficient (D) of the camera and the conversion function (H) between the camera plane and the laser plane using the coordinates of the vertex and the coordinates of the jig coordinate (S4)

The transformation function H is a function or a matrix representing the transformation relation between the coordinate of the jig X already known and known and the corresponding coordinate in the image.

5 is a view for explaining a configuration of a tread measuring apparatus to which a general optical cutting method is applied.

Referring to FIG. 5, the optical cutting method is used to calculate the actual coordinates of an object surface irradiated with a laser beam using a camera and a laser. The shape and size of the object can be calculated by irradiating the surface of the measurement object with a laser, and the camera installed at another angle captures the laser light and analyzes the pattern of the laser light.

In order to obtain the actual size and coordinates of the workpiece, the relationship between the laser light emitted by the camera and the workpiece must be determined. Therefore, the optical cutting method should be applied after the measurement object is set at a predetermined position.

In other words, all the information of the object to be measured is already known, and the corresponding point between the laser light reflected on the object and the light on the image photographed by the camera is found, and the transformation between the corresponding points is represented by the transformation matrix. It corresponds to the graph.

One point p 0 on the plane is represented by a homogeneous coordinate as shown in Equation 1 below.

Figure 112014016263849-pat00007

Then, the homography H to another plane of p 0 is expressed by Equation (2).

Figure 112014016263849-pat00008

In Equation (2), H is a 3 × 3 square matrix having eight free paths. Therefore, at least four corresponding points are required to obtain H, and therefore, a measurement object capable of clearly obtaining four or more corresponding points is required.

When four or more corresponding points are given, the transformation function H can be obtained by establishing a line form using this corresponding point and obtaining the solution. A typical method applied to solve the problem is SVD (Singular Value Decomposition).

On the other hand, the lens distortion coefficient D of the camera is necessary for extracting and correcting the lens distortion coefficient for the photographed image because distortion occurs due to lens distortion. The lens distortion model is shown in Equation 3 below.

Figure 112014016263849-pat00009

In Equation (3)

Figure 112014016263849-pat00010
Wow
Figure 112014016263849-pat00011
And x and y correspond to the coordinates of the input image as the coordinates before the lens distortion is corrected. Using the jig coordinates obtained from the jig, the lens distortion coefficient
Figure 112014016263849-pat00012
,
Figure 112014016263849-pat00013
Can be extracted and used for distortion correction.

2, the tread measuring apparatus obtains an input image B of a tread region irradiated with a laser beam from a camera (S5), and calculates a minimum threshold value (thr min ) and a maximum It determines the threshold value (thr max).

The minimum threshold value (thr min ) and the maximum threshold value (thr max ) are calculated based on the average and standard deviation of the background brightness distribution of the input image as shown in Equation (4).

Figure 112014016263849-pat00014

In Equation (4)

Figure 112014016263849-pat00015
Means mean and standard deviation, and α and β are constants, and appropriate values can be selected through experiments.

The manager divides the range of the threshold value into (N-1) intervals and calculates N threshold values (thr 1 , thr 2 , ..., thr N ). At this time, as the number of N increases, the amount of calculation increases. Therefore, an appropriate value is selected.

The image is thresholded with N threshold values to obtain images C i , i = 1, 2, ..., N for each threshold value. A maximum area is extracted as a tread area T i for the image C i and a skeleton P i of the area is extracted by applying a thinning algorithm to the tread area T i . Then, the tread left and right end coordinates (E i ) and shoulder left and right coordinates (S i ) are extracted from the skeleton (P i ).

An illustration, Figure 6 describes how to extract the left and right coordinates of the shoulder, referring this skeleton (P i) a method of extracting the solder left and right coordinates, the end coordinates and the straight line (A) connecting the center of the shoulder left and right coordinates Select the farthest position when the waterline is turned down at each position.

The tread measuring apparatus measures the symmetry degree by using the left and right end coordinates (E i ) and the left and right coordinates (S i ) of the left and right treads, and selects a threshold value, best be determined by a threshold value (thr opt). (S6) If, tread measuring apparatus determines in error if symmetrical about a not satisfactory for all thresholds.

The tread measuring apparatus obtains a thresholded image C opt or a skeletal coordinate P opt by applying an optimal threshold thr opt in the input image B and uses the skeletal coordinates P opt (E opt ) and the shoulder coordinate (S opt ) of the tread (S7, S8)

The tread measuring apparatus calculates coordinates obtained by correcting the lens distortion using the lens distortion correction model of Equation (2) for the end coordinates (E opt ) and shoulder coordinates (S opt ) (S9)

Figure 112014016263849-pat00016

here,

Figure 112014016263849-pat00017
(2) as a lens distortion correction function.

The tread measuring apparatus calculates the actual distance coordinates as shown in Equation (6) by using the transformation function (H) after obtaining the lens-distortion-corrected coordinates (S10)

Figure 112014016263849-pat00018

The tread measuring apparatus calculates the full width and the width of the tread using the actual distance coordinates (E real , S real ) (S11). Since the tread width obtained by Equation (6) is sensitive to noise, .

In other words, the tread measuring apparatus has a lens distortion-corrected end coordinate (

Figure 112014016263849-pat00019
) And shoulder coordinates (
Figure 112014016263849-pat00020
) Is calculated by performing a moving average operation using the end coordinates and the shoulder coordinates obtained in the previous step to obtain the average end coordinates
Figure 112014016263849-pat00021
) And average shoulder (
Figure 112014016263849-pat00022
) Coordinate. In calculating the moving average, it is possible to obtain a more stable value by removing the outlier by taking an average except for the deviation from the standard deviation or more.

The tread measuring apparatus applies the average end coordinates and the average shoulder coordinates to the transformation function H to output the final end coordinates E out and the final shoulder coordinates S out as shown in Equation 7, Since the coordinates consist of pairs of left and right coordinates, calculate the total width of the tread and the shoulder width by calculating the distance between the left and right coordinates.

Figure 112014016263849-pat00023

7 is a view for explaining a screen for displaying a tread width measured by a tread width measuring method according to an embodiment of the present invention.

As shown in FIG. 7, the tread measuring apparatus outputs a tread width measurement result screen when performing a calibration algorithm and a width measurement algorithm.

The position value in the tread width measurement result screen shows the difference in distance from the center position 375mm since the total image length is 750mm. Through the offset menu, the distance difference between the center of the tread at the center of the conveyor at 375mm is displayed, The center value can be changed as much as it is set in the above. At this time, the left and right movement of the tread can be confirmed through the position value.

In the tread width measurement result screen, the full width is displayed in green color and the shoulp width is displayed in green color, and the success or failure of tread detection is displayed in the operation status and whether the communication with the PLC is normal or not is displayed in the connection status.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims It can be understood that

Claims (5)

A method of measuring a tread width and a tread width, which is performed by a tread measuring apparatus for measuring a tread width and a width of a tread using a camera and a laser,
Extracting jig coordinates from a jig image of the jig using the camera to perform calibration, extracting a lens distortion coefficient of the camera using the jig coordinates, and a conversion function (H) between the camera plane and the laser plane;
Obtaining an input image (B) of the tread region irradiated with the laser light, calculating N threshold values using the brightness distribution of the input image, calculating an optimal threshold value for the tread contour extraction among the N threshold values (thr opt );
A skeleton coordinate P opt which is a thresholded image C opt is obtained by applying the optimal threshold value thr opt to the input image and a tread end coordinate P opt is calculated using the skeletal coordinate P opt E opt ) and a shoulder coordinate (S opt ); And
The end coordinate (E opt ) and the shoulder coordinate (S opt ) of the tread end coordinate (L opt ) are corrected using the lens distortion correction model
Figure 112014048754625-pat00024
) And shoulder coordinates (
Figure 112014048754625-pat00025
Calculating the actual distance coordinates (E real , S real ) using the transform function, and calculating the full width and the shallow width of the tread using the actual distance coordinates, Way.
The method of claim 1, wherein calculating the full width and the width of the tread using the actual distance coordinates comprises:
The lens distortion-corrected end coordinates (
Figure 112014016263849-pat00026
) And shoulder coordinates (
Figure 112014016263849-pat00027
) Is calculated by performing a moving average operation such that an outlier out of the standard deviation or more is removed by using the end coordinates and the shoulder coordinates of the previous end,
Figure 112014016263849-pat00028
) And average shoulder (
Figure 112014016263849-pat00029
) Coordinates;
Applying the average end coordinate and the average shoulder coordinate to the transform function to output a final end coordinate (E out ) and a final shoulder coordinate (S out ); And
Further comprising calculating a full width and a shoulder width of the tread using the final end coordinates and the final shoulder coordinates.
3. The method of claim 2, wherein calculating the full width and shoulder width of the tread using the final end coordinates and the final shoulder coordinates comprises:
Wherein the final end coordinate and the final shoulder coordinate are each made up of a pair of left and right coordinates and a distance between the left side and the right side coordinate is calculated to calculate the full width of the tread and the shoulder width. Way.
2. The method of claim 1, wherein performing the calibration comprises:
Wherein the calibration is performed using the intersection of the line and the line coordinates having the maximum brightness value and the maximum brightness degree after detecting the coordinates of the vertices of each jig in the jig image.
The method of claim 1, wherein calculating the N threshold values using the brightness distribution of the input image and determining an optimal threshold value (thr opt ) for extracting tread contour from the N threshold values comprises:
Calculating an average and a standard deviation of a background brightness distribution of the input image, and determining a minimum threshold and a maximum threshold based on the calculated average and standard deviation;
Dividing the range of the threshold value into (N-1) intervals and calculating the N threshold values;
Thresholding and binarizing the input image with the N threshold values to obtain an image C i for each threshold value and extracting a maximum region of the image C i as a tread region T i step;
Extracting tread left and right end coordinates (E i ) and shoulder left and right coordinates (S i ) with respect to the skeleton (P i ) by applying a thinning algorithm to the tread region (T i ); And
Measuring the left and right symmetry degree using the tread left and right end coordinates (E i ) and the shoulder left and right coordinates (S i ), and determining the threshold value having the greatest right-left symmetry degree as the optimum threshold value thr opt And measuring the tread width and the shoulps width.
KR1020140019074A 2014-02-19 2014-02-19 A method of measuring full and shawl width of tread of tire KR101412480B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
KR1020140019074A KR101412480B1 (en) 2014-02-19 2014-02-19 A method of measuring full and shawl width of tread of tire

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
KR1020140019074A KR101412480B1 (en) 2014-02-19 2014-02-19 A method of measuring full and shawl width of tread of tire

Publications (1)

Publication Number Publication Date
KR101412480B1 true KR101412480B1 (en) 2014-07-01

Family

ID=51740639

Family Applications (1)

Application Number Title Priority Date Filing Date
KR1020140019074A KR101412480B1 (en) 2014-02-19 2014-02-19 A method of measuring full and shawl width of tread of tire

Country Status (1)

Country Link
KR (1) KR101412480B1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016122069A1 (en) * 2015-01-29 2016-08-04 주식회사 다인 Method for measuring tire wear and device therefor

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20040053877A (en) * 2002-12-16 2004-06-25 한국전자통신연구원 Method of Lens Distortion Correction and Orthoimage Reconstruction In Digital Camera and A Digital Camera Using Thereof
JP2013039782A (en) 2011-08-19 2013-02-28 Yokohama Rubber Co Ltd:The Cross-sectional shape certification method of tread for tire
JP2013151119A (en) 2012-01-25 2013-08-08 Bridgestone Corp Method and device for measuring tread length

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20040053877A (en) * 2002-12-16 2004-06-25 한국전자통신연구원 Method of Lens Distortion Correction and Orthoimage Reconstruction In Digital Camera and A Digital Camera Using Thereof
JP2013039782A (en) 2011-08-19 2013-02-28 Yokohama Rubber Co Ltd:The Cross-sectional shape certification method of tread for tire
JP2013151119A (en) 2012-01-25 2013-08-08 Bridgestone Corp Method and device for measuring tread length

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016122069A1 (en) * 2015-01-29 2016-08-04 주식회사 다인 Method for measuring tire wear and device therefor

Similar Documents

Publication Publication Date Title
US10288418B2 (en) Information processing apparatus, information processing method, and storage medium
US9097514B2 (en) Device and method for inspecting tyre shape
US8121400B2 (en) Method of comparing similarity of 3D visual objects
US10006836B2 (en) Method and apparatus for detecting defects on tyres in a tyre production process
US20140043472A1 (en) Tire surface shape measuring device and tire surface shape measuring method
JP6052590B2 (en) Surface inspection apparatus and surface inspection method for automobile body
KR102027986B1 (en) Bead recognition apparatus using vision camera and method thereof
CN104458764B (en) Curved uneven surface defect identification method based on large-field-depth stripped image projection
CN114881915A (en) Symmetry-based mobile phone glass cover plate window area defect detection method
CN112634269B (en) Railway vehicle body detection method
KR101902068B1 (en) How to profile deviation analysis for the finished tire tread
CN117058411B (en) Method, device, medium and equipment for identifying edge appearance flaws of battery
KR101412480B1 (en) A method of measuring full and shawl width of tread of tire
JP6074284B2 (en) Method and apparatus for measuring shape of belt-like rubber member
KR101484170B1 (en) Assessment system and method for image projected from head up display
KR101637977B1 (en) Feature point detecting method of welding joint using laser vision system
US20130194417A1 (en) Evaluation unit, evaluation method, measurement system for a crash test vehicle measurement and a method for performing a crash test vehicle measurement
JP5157575B2 (en) Defect detection method
CN111536895B (en) Appearance recognition device, appearance recognition system, and appearance recognition method
KR20110100568A (en) Method and system for shroud nozzle centering guidance
JP4664805B2 (en) Face edge detection device, face edge detection method, and program
US10140692B2 (en) Tire image rectifying method
JP2004326382A (en) Component recognizing system and method, and program for recognizing component
CN110660073B (en) Straight line edge recognition equipment
JP5567951B2 (en) Tire master image generation method and master image generation apparatus

Legal Events

Date Code Title Description
A201 Request for examination
A302 Request for accelerated examination
E902 Notification of reason for refusal
E701 Decision to grant or registration of patent right
GRNT Written decision to grant
FPAY Annual fee payment

Payment date: 20170620

Year of fee payment: 4

FPAY Annual fee payment

Payment date: 20180620

Year of fee payment: 5

FPAY Annual fee payment

Payment date: 20190620

Year of fee payment: 6