JP3565497B2 - Tire toe value measurement system - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a tire toe value measuring system for measuring a toe value of a vehicle wheel.
[0002]
[Prior art]
As shown in FIG. 7, the toe value to which is one of the wheel alignments of the vehicle is defined by a difference between a front interval tf and a rear interval tr of the pair of left and right tires 71 and 72 when the vehicle is in a straight traveling state, The case where the front interval tf is smaller than the rear interval tr is called toe-in, and vice versa.
[0003]
The toe value to is set to a predetermined value depending on the type of the vehicle, and whether or not the toe value to of the completed vehicle is appropriate can be measured using, for example, a special measurement gauge 73 as shown in FIG. . The measurement gauge 73 causes the contact members 76, 77 on both sides to contact the middle of the tread surfaces 74, 75 of the tires 71, 72 from the front and rear of the tire of the automobile, and the gap between the contact members 76, 77. The distance is measured, and the front interval tf and the rear interval tr of the tires 71 and 72 are measured and calculated.
[0004]
In an actual wheel alignment inspection line, an inspection using, for example, a measurement unit 82 as shown in FIG. 9 is performed in relation to work efficiency. The measurement unit 82 presses the measurement plate 83 against the side surface of the tire 81 of the vehicle that has entered the inspection stage, measures the toe angle and camber angle of the tire 81 from the inclination of the measurement plate 83, and calculates the toe value to. In this case, since the measurement can be performed only by pressing the measurement plate 83 against the side surface of the tire, the time required for the measurement is short and the working efficiency is good.
[0005]
However, since the inspection using the measurement plate 83 must be performed with the tire 81 stopped, the tire 81 is rotated to adjust the toe angle in order to perform the measurement in consideration of the influence of the right-left deflection of the tire 81. It is necessary to measure the camber angle several times. There is also a problem that the measured values vary depending on the approach posture of the vehicle.
[0006]
As another measurement method, as shown in FIG. 10, the side surface shape of the tire is measured using a plurality of distance measurement sensors 92 provided in the measurement unit 91, and the toe angle and camber angle of the side surface of the tire 93 are calculated. There is also a method of calculating the toe value. In this case, since the tire 93 can be measured in a non-contact state, the tire 93 can be continuously measured by rotating the tire 93, and the measurement in consideration of the influence of the rotation of the tire 93 in the lateral direction can be easily performed.
[0007]
[Problems to be solved by the invention]
As described above, since the toe value measuring method used in the actual inspection is to measure the toe angle and camber angle of the side surface of the tire to calculate the toe value, an error caused by the tire is calculated. Because it is affected, it cannot be said to be an accurate measurement method of the toe value.
[0008]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a tire toe value measuring system capable of performing a precise measurement on a tread surface of a tire in a short time in measuring a toe value.
[0009]
[Means for Solving the Problems]
The toe value measuring system for a tire according to the present invention includes a first camera unit disposed behind a pair of left and right tires of a vehicle, a second camera unit disposed in front of the pair of left and right tires, The rear distance between the pair of left and right tires obtained based on an image of the pair of left and right tires taken from behind with the first camera unit, and the image of the pair of left and right tires taken from the front with the second camera unit. And a calculation processing means for calculating the toe value of the pair of left and right tires from the front interval of the pair of right and left tires calculated based on the toe value. Since the toe value measuring system measures the toe value from images behind and in front of the tire, it is hardly affected by errors caused by the tire.
[0010]
In addition, it is desirable to provide a rotation driving unit that rotates a pair of left and right tires of the automobile so that the measurement can be performed in consideration of the influence of the right-and-left vibration of the tire.
[0011]
Also, the first camera unit may be arranged so as to be able to photograph the left tire of the vehicle that has entered the inspection stage from behind, and may be able to photograph the right tire of the vehicle from behind. A third camera disposed so that the second camera unit can photograph the left tire of the vehicle that has entered the inspection stage from the front, and a second camera that is disposed on the inspection stage. And a fourth camera disposed so as to be able to photograph the right tire of the vehicle from the front.
[0012]
In this case, the lenses of the first camera and the second camera are disposed so as to face forward in the traveling direction of the vehicle, and the lenses of the third camera and the fourth camera are respectively directed backward in the traveling direction of the vehicle. And the rear distance and the front distance of the tires are determined by using the installation distance between the first camera and the second camera and the installation distance between the third camera and the fourth camera. Is also good.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a toe value measuring system for a tire according to an embodiment of the present invention will be described.
[0014]
As shown in FIG. 1, the toe value measuring system A includes a rotation drive mechanism 5 for rotating a pair of left and right tires 3 and 4 of an automobile 2 having entered an inspection stage 1 and a first drive mechanism 5 disposed behind the tires. The camera unit 6, a second camera unit 7 disposed in front of the tires 3 and 4, and an arithmetic process for obtaining a toe value to based on images captured by the first camera unit 6 and the second camera unit 7. And an arithmetic processing means 8 for performing the operation.
[0015]
The rotation drive mechanism 5 is, for example, a roller 9 that rotatably supports the tires 3 and 4 and is rotated by a predetermined angle by a servomotor (not shown). The tires 3 and 4 can be rotated by a predetermined angle depending on the ratio to the outer diameter of the roller 9.
[0016]
As shown in FIG. 2, the first camera unit 6 includes a first camera 11 disposed so as to be able to photograph the left tire 3 of the automobile 2 on the inspection stage 1 from behind, and a right tire 4. A second camera 12 is provided so as to be able to photograph from behind. The second camera unit 7 includes a third camera 13 disposed so that the left tire 3 can be photographed from the front, and a fourth camera 14 disposed so that the right tire 3 can be photographed from the front. It has.
[0017]
As shown in FIG. 1, the first camera 11 turns the left tire 3 of the automobile 2 on the inspection stage 1 from the lower rear side with the lens 11 a facing forward in the traveling direction of the automobile 2, and from the rear of the tire 3. The tread surface 3 a at the height of the rotating shaft 15 is installed so that it can be photographed.
[0018]
As shown in FIG. 1, the third camera 13 rotates the left tire 3 of the vehicle that has entered the inspection stage 1 from the front of the tire 3 with the lens 13 a facing backward from the lower front in the traveling direction of the vehicle 2. The tread surface 3b at the height of the shaft 15 is installed so that it can be photographed.
[0019]
FIG. 1 is a left side view of the vehicle 2 entering the inspection stage 1, but the same is true of the right side of the vehicle 2, that is, the second camera 12 is connected to the inspection stage 1 like the first camera 11. The right tire 4 of the car 2 is mounted so that the lens 12a faces forward from the lower rear side in the traveling direction of the car 2 so that the tread surface 4a at the height of the rotating shaft 16 can be photographed from behind the tire 4. It is. Similarly to the third camera 13, the fourth camera 14 turns the right tire 4 of the vehicle 2 that has entered the inspection stage 1 from the lower front to the rear in the traveling direction of the vehicle 2 with the lens 14 a facing the tire 4. The tread surface 4b at the height of the rotation shaft 16 is installed so as to be able to photograph from the front.
[0020]
In the first camera unit 6, the installation distance Cr between the first camera 11 and the second camera 12 installed behind the tires 3 and 4 can be determined in a state where the cameras 11 and 12 are installed. ing. Further, the second camera unit 7 determines the installation distance Cf between the third camera 13 and the fourth camera 14 installed in front of the tires 3 and 4 in a state where the cameras 13 and 14 are installed. Has become.
[0021]
The arithmetic processing unit 8 includes an arithmetic processing unit 17 and a storage unit 18, and as shown in FIG. 3, calculates a rear interval tr of the tires 3 and 4 from an image captured by the first camera unit 6. The arithmetic processing (I), the second arithmetic processing (III) for calculating the front interval tf of the tires 3 and 4 from the image captured by the second camera unit 7, and the tire 3 and the tire 3 obtained in the first arithmetic processing. A third calculation process (IV) of calculating a toe value to from the rear interval tr of No. 4 and the front interval tf of the tires 3 and 4 obtained in the second calculation process is performed.
[0022]
Hereinafter, a method of measuring the toe value to in this toe value measurement system will be described.
[0023]
First, as shown in FIG. 3 (I), the toe value to is measured by the cameras 11 and 12 of the first camera unit 6 using the rear tread surface 3a of the left tire 3 and the right tire 4 thereof. A rear interval tr between the tires 3 and 4 is obtained based on an image obtained by photographing the rear tread surface 4a.
[0024]
More specifically, since the lens 11a of the camera 11 of the first camera unit 6 and the lens 12a of the camera 12 are directed forward in the traveling direction of the automobile 2, each image taken as shown in FIGS. The center O of the camera coincides with the center of the line of sight of each of the cameras 11 and 12, and by taking the coordinates of the tread surfaces 3a and 4a in the image with the center O of the image as the origin, each tread surface 3a, The relative coordinates of 4a can be obtained.
[0025]
From this, as shown in FIG. 4A, the image taken by the first camera 11 is located on the rotation axis k of the tire 3 in the middle of the tread surface 3a suitable for measuring the toe value to. The coordinates (X ₁ , Y ₁ ) of the specific tread pattern 21 are obtained, and as shown in FIG. 4B, the toe on the rotation axis k of the tire 4 is selected from the images taken by the second camera 12. The coordinates (X ₂ , Y ₂ ) of the specific tread pattern 22 in the middle of the tread surface 4a suitable for measuring the value to are obtained (Y ₁ = Y ₂ ).
[0026]
Then, based on the coordinates (X ₁ , Y ₁ ) of the tread pattern 21, the coordinates (X ₂ , Y ₂ ) of the tread pattern 22 and the distance Cr between the first camera 11 and the second camera 12, the tr = _Cr-X 1 + _{X 2} calculates the backward interval tr of the tires 3 and 4 (the right X-coordinate from the center origin O of the image in FIG. 4 +, the left X coordinate - and).
[0027]
Further, the image pattern of the tread pattern 21 photographed by the first camera 11 and the image pattern of the tread pattern 22 photographed by the second camera 12 are stored in the storage unit 18 of the arithmetic processing unit 8.
[0028]
Next, as shown in FIG. 3 (II), the right and left tires 3 and 4 are rotated by 180 degrees by rotating the roller 9 of the rotation drive mechanism 5 by a predetermined angle.
[0029]
Next, as shown in FIG. 3 (III), an image of the third camera 13 and the fourth camera 14 photographing the front tread surface 3b of the left tire 3 and the front tread surface 4b of the right tire. Of the tires 3 and 4 is calculated based on the following formula.
[0030]
More specifically, since the lens 13a of the camera 13 and the lens 14a of the camera 14 of the second camera unit 7 are directed backward in the traveling direction of the automobile 2, each image taken as shown in FIGS. Of the tread plane (3b, 4b) in the image with the center O of the image as the origin, thereby obtaining the tread plane for the camera 13, 14 The relative coordinates of (3b, 4b) can be obtained.
[0031]
From this, as shown in FIG. 5A, for example, by performing a pattern matching process after inverting the image up and down from the images captured by the third camera 13, the first camera 11 The tread pattern 21 previously stored in the storage unit 18 of the arithmetic processing unit 8 is determined from the captured image, and its coordinates (X ₃ , Y ₃ ) are obtained. Further, as shown in FIG. 5 (b), among the images taken by the fourth camera 14, and indexing the tread pattern 22 stored in the storage unit 18 of the earlier processing means 8, the coordinates (X ₄ , Y ₄ ).
[0032]
Then, based on the coordinates (X ₃ , Y ₃ ) of the tread pattern 21, the coordinates (X ₄ , Y ₄ ) of the tread pattern 22 and the installation distance Cf between the third camera 13 and the fourth camera 14, The forward interval tf between the tires 3 and 4 is calculated from tf = Cf−X ₃ + X ₄ (in FIG. 5, the right X coordinate is + and the left X coordinate is − from the center O of the image).
[0033]
As shown in FIG. 3 (IV), the toe value to is obtained from the rear distance tr of the tires 3 and 4 and the front distance tf of the tires 3 and 4 obtained in FIGS. The toe value to is obtained from −tf.
[0034]
According to this toe value measuring system, since the toe value to is calculated from the tread surfaces (3a, 3b, 4a, 4b) of the tires 3, 4, the toe value to can be measured accurately and the tires 3, 4 can be measured. Is rotated to perform measurement, so that the measured value can be taken into account the lateral runout of the tires 3 and 4, and more precise measurement can be performed.
[0035]
As described above, the toe value measuring system according to one embodiment of the present invention has been described, but the present invention is not limited to the above system.
[0036]
For example, a predetermined point on the tread surface of the left and right tires is marked, the tires are photographed by the first camera unit and the second camera unit, and the markings are detected by the arithmetic processing means from the images and the left and right tires are detected. The front interval and the rear interval of the tire may be calculated from the marking interval. In this case, a white paint may be used to facilitate the detection of the marking in the image of the tread surface of the tire.
[0037]
As shown in FIG. 6, the toe value measuring system A is provided on the front wheel 31 and the rear wheel 32 of the vehicle 2 that has entered the inspection stage 1, and the toe value to of the front wheel 31 and the rear wheel 32 of the vehicle 2 is provided. May be measured simultaneously.
[0038]
Further, the pattern of the tread surface photographed by the camera is not limited to a specific pattern at the center of the tire, and may be, for example, any groove continuous in the circumferential direction of the tire. In the toe value measurement described above, the pattern matching step can be unnecessary or simplified.
[0039]
The toe value measuring system can also calculate the toe angle of the tire from the rear image and the front image of each tire.
[0040]
【The invention's effect】
The toe value measuring system according to the present invention includes: a first camera unit disposed behind a pair of left and right tires of a vehicle; a second camera unit disposed in front of the pair of left and right tires; The rear interval of the pair of left and right tires obtained based on an image obtained by photographing the pair of left and right tires from behind with the camera unit, and the image obtained by photographing the pair of left and right tires from the front with the second camera unit. A calculating means for calculating the toe value of the pair of left and right tires from the determined front distance between the pair of right and left tires, so that the tire itself is compared with a conventional method of measuring the toe value from the side of the tire. Can eliminate the toe value measurement error caused by the distortion of the shape.
[0041]
In addition, by rotating a pair of left and right tires of the automobile by the rotation driving means, it becomes possible to perform measurement in consideration of the influence of the lateral run-out of the tires.
[0042]
Further, a first camera unit is arranged so that a tread surface of a left tire of the vehicle that has entered the inspection stage can be photographed from behind, and a tread surface of a right tire of the vehicle. A second camera disposed so as to be able to photograph from behind, wherein the second camera unit is arranged so as to be able to photograph from the front a tread surface of a left tire of the vehicle that has entered the inspection stage. And a fourth camera arranged so that the tread surface of the right tire of the vehicle can be photographed from the front, to obtain a more accurate image of the left and right tires. Therefore, more accurate toe value measurement can be performed.
[0043]
In addition, the lenses of the first camera and the second camera are disposed so as to face forward in the traveling direction of the vehicle, and the lenses of the third camera and the fourth camera are respectively disposed backward in the traveling direction of the vehicle. To determine the rear and front intervals of tires using the distance between the installation of the first camera and the second camera and the distance between the installation of the third camera and the fourth camera And a more accurate toe value measurement can be performed.
[Brief description of the drawings]
FIG. 1 is a left side view of a tire toe value measuring system according to an embodiment of the present invention.
FIG. 2 is a plan view schematically showing a toe value measuring system according to one embodiment of the present invention.
FIG. 3 is a flowchart of a toe value measurement system according to an embodiment of the present invention.
FIG. 4 is a view showing an image of a first camera unit of the toe value measuring system according to one embodiment of the present invention.
FIG. 5 is a view showing an image of a second camera unit of the toe value measuring system according to one embodiment of the present invention.
FIG. 6 is a side view of a toe value measuring system according to another embodiment of the present invention.
FIG. 7 is a conceptual diagram of a toe value.
FIG. 8 is a perspective view of a toe value measurement gauge.
FIG. 9 is a schematic perspective view of a conventional toe value measuring unit.
FIG. 10 is a schematic perspective view of a conventional toe value measuring unit.
[Explanation of symbols]
Reference Signs List 1 inspection stage 2 automobile 3 left tire 3a, 3b tread surface 4 right tire 4a, 4b tread surface 5 rotation drive mechanism 6 first camera unit 7 second camera unit 8 arithmetic processing means 11 to 14 camera 15 tire rotation axis 17 arithmetic processing unit 18 storage unit A toe value measurement system

Claims (4)

A first camera unit disposed behind a pair of left and right tires of the vehicle,
A second camera unit disposed in front of the pair of left and right tires,
A rear distance between the pair of left and right tires obtained based on an image obtained by photographing the pair of left and right tires from behind with the first camera unit, and an image obtained by photographing the pair of right and left tires from the front with the second camera unit A toe value measuring system for calculating a toe value of the pair of left and right tires from a front interval of the pair of right and left tires obtained based on the toe value. The tire toe value measuring system according to claim 1, further comprising a rotation drive unit configured to rotate a pair of left and right tires of the vehicle. A first camera disposed so that the first camera unit can photograph a tread surface of a left tire of the vehicle that has entered the inspection stage from behind, and a tread surface of a right tire of the vehicle that is rearward. And a second camera arranged to be able to shoot from
A third camera disposed so that the second camera unit can photograph a tread surface of a left tire of the vehicle that has entered the inspection stage from the front, and a tread surface of a right tire of the vehicle that faces the front. The tire toe value measuring system according to claim 1, further comprising a fourth camera arranged so as to be able to take an image from the camera. The lenses of the first camera and the second camera are disposed so as to face forward in the traveling direction of the vehicle, and the lenses of the third camera and the fourth camera are respectively directed backward in the traveling direction of the vehicle. 4. The tire toe value measuring system according to claim 3, wherein the tire toe value measuring system is provided.

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