JP2007085836A - Three-dimensional shape measuring system, three-dimensional shape measuring method, and installation condition correction method for photographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a three-dimensional shape measuring system, a three-dimensional shape measuring method, and an installation condition correction method for a photographic apparatus characterized by simple structure, ease of use, and ability to measure the shape of tire with high accuracy, even when it is made to run at a high speed. <P>SOLUTION: The three-dimensional shape measuring system 11 comprises a liquid-crystal projector 14 for projecting a grid-like optical mark onto a rolling tire by using a continuously emitting light-emitting source, two video cameras 16, 18 for photographing the projected optical mark, and a data processing apparatus 20 for calculating each three-dimensional coordinates of a grid point, constituting the optical mark, by processing image data photographed by the video cameras 16, 18 and for displaying the shape of a side wall part, on the basis of each calculated three-dimensional coordinates. Since the optical mark is projected from the installation position of the liquid-crystal projector 14, that is, it is a fixed position, the relative speed between the grid point by the optical mark and the photographing apparatus is almost zero, even if the running speed of the tire is increased. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a three-dimensional shape measurement system that measures the three-dimensional shape of a rolling tire, a three-dimensional shape measurement method, and an installation state correction method for a photographing apparatus.

  Tests for measuring the deformation of each part of a rotating tire have been conducted. Conventionally, in this test, a marker is attached to a tire, and the tire is rotated into a rolling tire, and the position of the marker is photographed with a video camera or the like in three-dimensional coordinates.

  However, when the tire rotation speed (running speed) becomes high, an image in which the marker flows is captured. For this reason, there is a problem that it is difficult to measure the characteristic shape of the tire part in high-speed running. This problem was particularly serious when testing at high speeds.

  Moreover, in order to measure the deformation | transformation of a rolling tire in detail, although it is necessary to raise the sticking density (number of sticking per unit area) of a marker, it is necessary to limit the sticking range from a viewpoint of sticking man-hours. For this reason, there is also a problem that measurement of three-dimensional coordinates is impossible when only a photographed image of only one camera is obtained due to the blind spot.

Patent Document 1 describes measuring a tire cross-sectional shape under dynamic load by operating a laser slit light on a dynamically loaded tire and reading the reflected light with a camera to acquire three-dimensional image data. Has been proposed. However, this measurement has a drawback that it is difficult to measure the tire shape at a certain moment during tire rotation. In addition, the laser apparatus is expensive, and it is necessary to take safety measures when handling it, and there is a problem that the apparatus configuration becomes complicated.
Japanese Patent Laid-Open No. 7-174528

  In consideration of the above facts, the present invention provides a three-dimensional shape measurement system, a three-dimensional shape measurement method, and an imaging device that are easy to use with a simple configuration and that can measure a tire shape with high accuracy even when traveling at high speed. It is an object to provide a state correction method.

  The invention according to claim 1 is a projection device that projects a lattice-shaped light mark on a rolling tire using a light emitting source that emits light continuously, and at least two of the projected light marks. Calculated by the imaging device, calculation processing means for calculating each three-dimensional coordinate of a plurality of components constituting the optical mark by calculating the image data captured by the imaging device, and the calculation processing means Display means for displaying at least a part of the shape of the tire based on the three-dimensional coordinates.

  A commercially available thing can be used as said arithmetic processing means and a display means.

  According to the first aspect of the present invention, the light mark projected on the object to be measured is photographed simultaneously by the two photographing devices.

  Then, the three-dimensional coordinates of the light mark are calculated for each lattice point from the two images respectively photographed by each photographing device by the arithmetic processing means.

  Furthermore, the display means displays the shape of at least a part of the tire as the object to be measured, with the three-dimensional coordinates of the lattice points within the intended range.

  In the first aspect of the invention, the light mark is projected (projected) from the installation position of the projection device, that is, from the fixed position, instead of attaching the marker to the tire. Thereby, even if the running speed of the tire increases, the relative speed between the lattice point by the optical mark and the photographing apparatus is almost zero. Therefore, a three-dimensional shape measurement system for a rolling tire capable of measuring a tire shape at a certain moment with high accuracy even when the tire is driven at a high speed is realized. Moreover, even a large tire can be measured accurately.

  Further, by projecting the light mark, it is possible to keep the projected light mark within the photographing range without performing the work of pasting the marker as in the prior art. Therefore, workability is improved.

  The invention according to claim 2 is characterized in that the plurality of constituent parts are lattice points.

  As a result, the above-described components are clarified and data processing is easy.

  According to a third aspect of the present invention, the light emitting source is a liquid crystal projector.

  As a result, a good light mark is projected using a light source that is simple and inexpensive to operate.

  According to a fourth aspect of the present invention, the photographing apparatus is a video camera.

  As a result, the photographing apparatus can be a commercially available inexpensive video camera, and the apparatus configuration is simplified.

  By the way, in the first aspect, since the light path of the projection light by the projection device is stable and goes straight, by measuring the optical path for each light mark after fixing the relative position between the photographing device and the projection device, It is possible to measure a three-dimensional shape only with data from one imaging device.

  Therefore, the invention according to claim 5 uses a light emitting source that emits light continuously, projects a grid-like light mark on a rolling tire by a projection device, and the projected light marks are separated from each other by a distance. Photographed at different positions, and by calculating the photographed image data, each three-dimensional coordinate of a plurality of components constituting the light mark is calculated, and based on the calculated three-dimensional coordinates, The shape of at least a part of the tire is displayed.

  As a result, even if only one imaging device is used, the three-dimensional shape can be measured with high accuracy in a state where the tire is rolled at a high speed, that is, in a state where the tire is driven at a high speed.

  The invention described in claim 6 is characterized in that lattice points are used as the plurality of constituent parts.

  As a result, the above-described components are clarified and data processing is easy.

  The invention according to claim 7 is a method for correcting an installation state of a photographing apparatus used for measuring a three-dimensional shape of a rolling tire, wherein a marker is pasted on a wheel incorporated in the tire in advance. The marker is photographed by at least two photographing devices in a state of rolling, and at least one of an installation angle error and an installation position error of the photographing device is calculated, and at least one of the installation angle and the installation position of the photographing device is calculated. It is characterized by correcting.

  In the invention according to claim 7, the marker pasted on the wheel is photographed simultaneously by at least two photographing devices.

  Next, based on the target installation position and target installation angle of the imaging device, the locus of the marker is analyzed, and an axial direction error (for example, an error in the Z-axis direction coordinate) in the two three-dimensional coordinates obtained therefrom is calculated. Further, the sum of squared errors is calculated. Based on the calculated error sum of squares, the installation angle (yaw angle, roll angle, pitch angle, etc.) and installation position of the photographing apparatus are optimized.

  Further, the installation angle and the installation position of each photographing apparatus are corrected so that the sum of squares of the difference between the obtained three-dimensional coordinates and the three-dimensional coordinates assumed by the circular motion around the tire axis is minimized.

  According to the seventh aspect of the present invention, it is possible to optimize the installation angle and the installation position of the photographing apparatus by a simple method.

  According to the present invention, a three-dimensional shape measurement system, a three-dimensional shape measurement method, and an installation state correction method for a photographing apparatus that can measure a tire shape with high accuracy even when traveling at high speed are realized with a simple configuration. Is done.

  Hereinafter, embodiments will be described and embodiments of the present invention will be described. In the second and subsequent embodiments, the same components as those already described are denoted by the same reference numerals and description thereof is omitted.

[First Embodiment]
First, the first embodiment will be described. As shown in FIG. 1, in the three-dimensional shape measurement system 11 according to the present embodiment, a lattice-shaped light mark 12 is formed on a rolling pneumatic tire 10 using a light emitting source that continuously emits light (see FIG. 3). The liquid crystal projector 14 for projecting the image, the two video cameras 16 and 18 for photographing the light mark 12, and the data photographed by the video cameras 16 and 18 are processed and the shape of the pneumatic tire 10 is displayed on the screen. A data processing device 20.

  In the present embodiment, the light mark 12 is projected onto the rolling pneumatic tire 10 from the liquid crystal projector 14 whose position is fixed.

  Further, the position of the lattice point 12P of the optical mark 12 is photographed by the two video cameras 16 and 18. Data captured by the video cameras 16 and 18 is transmitted to the data processing device 20, and the data is processed. And the data processor 20 displays the shape of the pneumatic tire 10 to roll on a screen based on the data obtained by the calculation process.

Hereinafter, it will be described with reference to FIG. 2 that the data processing device 20 calculates a three-dimensional image of the rolling pneumatic tire 10 based on images taken by the two video cameras 16 and 18. To do. In Figure _{2, camera a (x a,} y a, z a) are coordinates of the installation position of the video camera _{16, camera b (x b,} y b, z b) the coordinates of the installation position of the video camera 18 is there. Then, target (x, y, z) is the position of one lattice point formed by the optical mark 12.

  x, y and z indicating the coordinates of the target are calculated by the following equations. Note that z can be calculated by two formulas as shown below, but the values are identical to each other in principle.

以上説明したように、本実施形態では、位置が固定された２台のビデオカメラ１６、１８から光マーク１２を投射（投影）している。これにより、空気入りタイヤ１０の走行速度が上昇しても、光マーク１２による格子点１２Ｐと撮影装置との相対速度がほとんどゼロである。従って、高速走行させても高い精度で測定可能な転動タイヤの三次元形状測定システム１１が実現される。

As described above, in the present embodiment, the optical mark 12 is projected from the two video cameras 16 and 18 whose positions are fixed. Thereby, even if the traveling speed of the pneumatic tire 10 increases, the relative speed between the lattice point 12P by the light mark 12 and the photographing apparatus is almost zero. Therefore, the rolling tire three-dimensional shape measurement system 11 that can measure with high accuracy even when traveling at high speed is realized.

  Further, by projecting the light mark 12 with the liquid crystal projector 14, it is possible to keep the projected light mark within the photographing range without performing the work of pasting the marker as in the prior art. Therefore, workability is improved.

  In addition, since the liquid crystal projector 14 is used as a light source for projecting the light mark 12, it is possible to project a good light mark 12 using a light source that is easy to operate and inexpensive.

  In addition, since the video cameras 16 and 18 are used as photographing devices for photographing the lattice points of the light mark 12, a commercially available inexpensive video camera can be used as the photographing device, thereby simplifying the device configuration.

(Example of the first embodiment)
In this embodiment, a liquid crystal projector manufactured by Sony (trade name: VPL-PX1) is used as the liquid crystal projector 14. As the video cameras 16 and 18, a video camera manufactured by Photoron (trade name: FastcamMax) was used. Further, as the data processing apparatus 20, an apparatus in which high-end motion analysis software (trade name: TEMA) manufactured by Image System was installed was used. Further, a tire whose surface was painted white was used as the pneumatic tire 10 to be rolled.

  Then, a normal rim was incorporated into the pneumatic tire 10 to obtain a normal internal pressure, which was attached to a test apparatus for rotating the tire, and a normal load was applied. Here, “regular rim” refers to the standard rim in the applicable size specified in the 2004 YEAR BOOK issued by JATMA, for example, and “normal load” and “regular internal pressure” are also issued by JATMA. This refers to the maximum load in the applicable size and ply rating defined in the 2004 YEAR BOOK and the air pressure for the maximum load. When the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the respective standards are followed.

  The pneumatic tire 10 is rolled so as to travel at a speed of 30 km / h, and the black and white light marks 12 of 16 pixels × 16 pixels arranged in a lattice pattern are painted white. The image was projected on the side wall portion 10S, and photographed with the video cameras 16 and 18 under the condition of an exposure time of 1/2000 seconds. Images recorded by the video cameras 16 and 18 by this photographing are shown in FIG.

  Further, the data processing device 20 performs arithmetic processing on data indicating the position of each grid point 12P of the images recorded in the video cameras 16 and 18. Then, the shape of the sidewall portion 10 </ b> S of the pneumatic tire 10 was displayed on the screen provided in the data processing device 20. The display result is shown in FIG.

  For comparison, a white spot marker is pasted on the pneumatic tire 10 as in the past, and the pneumatic tire 10 is rolled so that it travels at a speed of 30 km / h. Taken at 18. An image obtained by this photographing is shown in FIG. In FIG. 10, it can be seen that the image flows at 30 km / h.

  In contrast to this, with the lattice-shaped light mark 12 projected by the liquid crystal projector 14 as in the present embodiment, a clear image is recorded on the video cameras 16 and 18 even when the vehicle is driven at a speed of 80 km / h. Therefore, it was confirmed that the three-dimensional shape of the pneumatic tire 10 can be measured with high accuracy even when traveling at high speed.

[Second Embodiment]
Next, a second embodiment will be described. In the present embodiment, only one of the video cameras 16 and 18 described in the first embodiment is used to measure the three-dimensional shape of the rolling pneumatic tire 10.

  Since the light path of the projection light from the liquid crystal projector 14 is stable and travels straight, by measuring the optical path for each light mark after fixing the relative positions of the video cameras 16 and 18 and the liquid crystal projector 14, one video A three-dimensional shape can be measured only by data obtained from a camera (for example, video camera 16).

  Hereinafter, it will be described with reference to FIG. 4 that the data processing device 20 calculates a three-dimensional image of the rolling pneumatic tire 10 based on an image taken by one video camera. Here, the y-direction position and the z-direction position are the same for the video cameras 16 and 18, and the center (intermediate position) of the two video cameras 16 and 18 is used as a reference point. Indicates that one of the coordinates indicating can be reduced.

  x, y and z indicating the coordinates of the target are calculated by the following equations. Note that z can be calculated by two formulas as shown below, but the values are identical to each other in principle.

本実施形態により、設置するビデオカメラの台数が第１実施形態に比べて１台減っても、転動する空気入りタイヤ１０の三次元形状を精度良く測定することができる。

According to the present embodiment, the three-dimensional shape of the rolling pneumatic tire 10 can be accurately measured even when the number of installed video cameras is reduced by one compared to the first embodiment.

(Example of the second embodiment)
The projection light from the liquid crystal projector 14 has a stable optical path and high linearity. Therefore, as shown in FIGS. 5 to 7, one light mark 12 viewed from one video camera 16 (see FIG. 3). A high correlation was obtained between the azimuth and the elevation angle and the three-dimensional coordinates of the optical mark 12 calculated from the two video cameras 16 and 18.

  Therefore, it has been found that by measuring these relationships in advance, it is possible to estimate the three-dimensional coordinates indicating the shape of the rolling pneumatic tire 10 even from an image taken with one video camera. .

[Third Embodiment]
Next, a third embodiment will be described. As shown in FIG. 8, in the present embodiment, a plurality of markers 22 are attached in advance to a wheel incorporated in the pneumatic tire 10.

  Further, the pneumatic tire 10 incorporating this wheel is attached to the test apparatus described in the first embodiment and rotated, and the marker 22 is photographed simultaneously by the two video cameras 16 and 18. In the present embodiment, the video cameras 16 and 18 are arranged in a horizontal plane.

  Further, the trajectory of the marker 22 affixed to the wheel is analyzed based on the target installation position and target installation angle of the video cameras 16 and 18, and the video camera is set so that the square sum of the two Z-axis coordinate differences obtained therefrom is minimized. The yaw angle, roll angle, and pitch angle of 16, 18 are optimized with an Excel solver or the like.

  The installation angles of the video cameras 16 and 18 are converted into actual azimuths and elevation angles using the following equations in consideration of installation angle errors and the like.

本実施形態により、簡易な手法で、ビデオカメラ１６、１８の設置角度及び設置位置を補正して最適化させることができる。

According to the present embodiment, the installation angle and the installation position of the video cameras 16 and 18 can be corrected and optimized by a simple method.

(Example of the third embodiment)
In this embodiment, the trajectory of the marker 22 is analyzed based on the target installation angle and target installation position of the video cameras 16 and 18, and two Z-axis coordinate differences obtained therefrom (the height when two cameras are horizontally arranged) are analyzed. The yaw angle, roll angle, and pitch angle of the video cameras 16 and 18 were optimized using an Excel solver so that the square sum of the difference) was minimized. The results are shown in Table 1.

また、タイヤ軸回りの円運動で想定される三次元座標を初期値として、ビデオ画像から上記のようにして得られた三次元座標との差異の二乗和が最小となるように、ビデオカメラ１６、１８の設置位置、設置角度をエクセルのソルバーを使用して最適化させた。

Further, the video camera 16 is set so that the sum of squares of the difference from the three-dimensional coordinates obtained as described above from the video image is minimized with the three-dimensional coordinates assumed by the circular motion around the tire axis as an initial value. , 18 installation positions and installation angles were optimized using an Excel solver.

  In the present example, the cross-sectional shape of the sidewall portion at the tire rotation axis coordinates was calculated from the video images of the two video cameras 16 and 18 using the obtained optimization result. The calculated results are shown in FIG.

  As described above, according to this embodiment, the installation angle and the installation position of the video cameras 16 and 18 are corrected and optimized by a simple method, and the three-dimensional shape such as the sidewall portion of the rolling pneumatic tire 10 is measured. can do.

  The embodiments of the present invention have been described above with reference to the embodiments. However, these embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. Needless to say, the scope of rights of the present invention is not limited to the above embodiment.

It is a mimetic diagram showing the three-dimensional shape measuring system concerning a 1st embodiment. It is explanatory drawing of the principle which calculates | requires a three-dimensional coordinate in 1st Embodiment. In the Example of 1st Embodiment, it is a side view which shows the optical mark projected on the pneumatic tire which rolls. In the Example of 1st Embodiment, it is a graph which shows the shape of the sidewall part of the pneumatic tire which rolls. It is the graph obtained by the Example of 2nd Embodiment. It is the graph obtained by the Example of 2nd Embodiment. It is the graph obtained by the Example of 2nd Embodiment. It is explanatory drawing which shows measuring the three-dimensional shape of the pneumatic tire which rolls in 3rd Embodiment. In the Example of 3rd Embodiment, it is a graph which shows the shape of the sidewall part of the pneumatic tire which rolls. It is a side view which shows the optical mark projected on the pneumatic tire which rolls in a prior art example.

Explanation of symbols

10 Pneumatic tire (tire)
DESCRIPTION OF SYMBOLS 11 Three-dimensional shape measurement system 12 Optical mark 12P Lattice point 14 Liquid crystal projector 16 Video camera 18 Video camera 20 Data processing apparatus (arithmetic processing means, display means)
22 Markers

Claims (7)

A projection device that projects a lattice-shaped light mark on a rolling tire using a light emitting source that continuously emits light,
At least two photographing devices for photographing the projected light mark;
An arithmetic processing means for calculating each three-dimensional coordinate of a plurality of constituent parts constituting the optical mark by performing arithmetic processing on the image data photographed by the photographing apparatus;
Display means for displaying the shape of at least a part of the tire based on the three-dimensional coordinates calculated by the arithmetic processing means;
A three-dimensional shape measuring system comprising:   The three-dimensional shape measurement system according to claim 1, wherein the plurality of constituent parts are lattice points.   The three-dimensional shape measurement system according to claim 1, wherein the light source is a liquid crystal projector.   The three-dimensional shape measurement system according to claim 1, wherein the photographing device is a video camera. Using a light emitting source that emits light continuously, a grid-shaped light mark is projected onto a rolling tire by a projection device,
Photograph the projected light marks at different positions from each other,
By calculating the captured image data, each three-dimensional coordinate of a plurality of components constituting the light mark is calculated,
A three-dimensional shape measuring method, comprising: displaying at least a part of the shape of the tire based on the calculated three-dimensional coordinates.   The three-dimensional shape measuring method according to claim 5, wherein lattice points are used as the plurality of constituent parts. A method for correcting an installation state of a photographing apparatus used for measuring a three-dimensional shape of a rolling tire,
Affix the marker in advance on the wheel built into the tire,
Photographing the marker with at least two photographing devices in a state where the tire is rolled,
A method for correcting an installation state of an imaging apparatus, wherein at least one of an installation angle error and an installation position error of the imaging apparatus is calculated and at least one of the installation angle and the installation position of the imaging apparatus is corrected.

Images