JP5228731B2 - Vehicle wheel position measuring device by image processing - Google Patents

Description

  The present invention relates to a vehicle wheel position measuring device using image processing, and more particularly to a vehicle wheel position measuring device using image processing for measuring the position of a vehicle wheel traveling on a chassis dynamometer.

  2. Description of the Related Art Chassis dynamometers are known as devices that perform engine performance inspection and the like by simulating road driving in a vehicle such as an automobile indoors. The chassis dynamometer arranges the roller in the pit so that its top is at the same height as the floor, fixes the vehicle so that the tire is directly above the roller, and drives the tire under various driving conditions, It is a device for inspecting the power performance of a vehicle.

  In such a chassis dynamometer, it is desirable that the center of the tire is always installed directly above the roller in order to simulate flat road driving. However, during a power performance test, the vehicle may move in the front-rear direction of the roller due to fluctuations in the driving force of various tires. In such a case, an error may occur in the measured value in the test due to the center of the tire deviating from directly above the roller.

  Conventionally, as a means of coping with such problems, images of tire circumferences, seams between wheels and tires, or seams provided on foils are acquired, and the center of the foil is measured by image processing to determine the installation state of the vehicle The technique to do is disclosed (for example, refer patent document 1). Since it is difficult to measure the foil center with other measuring means such as a laser, the measuring means using image processing as disclosed in Patent Document 1 is an effective technique.

JP-A-2005-351730

  However, the conventional technique described in Patent Document 1 is a technique for measuring the foil center by processing images of the outer periphery of the foil, the seam between the foil and the tire, or the seam provided on the foil. It is necessary to image the entire foil. For this reason, the imaged image has a small foil center, and it is difficult to measure the center of the foil with high accuracy. In addition, the foil center may be erroneously measured due to the influence of dirt on the foil or fluctuations in lighting conditions.

  Furthermore, although it is set as the structure which calculates | requires the center of foil based on the shape of foil, the position of the center of foil shape and an actual rotation center may differ. For example, the shape center of the foil having a non-uniform foil balance and the actual dynamic rotation center may be misaligned by several millimeters. In this way, when the center of the foil shape is not an accurate rotation center, a measurement error occurs in the engine performance inspection due to the deviation between the center of the foil shape and the rotation center, and an accurate inspection result is obtained. There was no fear.

  In view of the above, an object of the present invention is to provide a vehicle wheel position measuring device by image processing capable of measuring the position of a vehicle under performance test more accurately and with high accuracy.

The present invention that solves the above problems is a wheel position measuring device that measures the position of a vehicle foil that is installed on a roller and performs a performance test by rotating the foil,
A line for imaging the rotating foil, the scanning direction being set in a horizontal direction or a vertical direction at a position facing the rotating foil and the field of view intersecting with the outer peripheral edge of the foil at two points. A sensor,
The outer peripheral edge of the foil is detected on the image acquired by the line sensor, and the position of the foil in the scanning direction is calculated based on the detected position of the outer peripheral edge of the foil. Image processing means for calculating a position of the foil in a direction perpendicular to the scanning direction based on a distance between the foil ,
Tona is,
The image processing means includes
A line sensor image is generated by arranging images taken by the line sensor in time series,
The locus of the foil on the line sensor image is extracted, and the positions u ₁ (t) and u ₂ (t) of the outer peripheral edge of the foil on the line sensor image at time t are detected, and the line sensor at time t is detected. Detecting the distance w (t) (= u ₂ (t) −u ₁ (t)) between the outer peripheral edges of the foil on the image;
Transform coefficient k _x, k _y and time position u of the outer peripheral edge of the foil on the line sensor image at _{t 1 (t), u 2} (t) and said at time t on the line sensor image of the foil between the outer peripheral edge of the The center position (x (t), y (t)) of the foil at time t is calculated by performing the following expressions (3) and (4) using the distance w (t). A vehicle wheel position measuring device by image processing.
x (t) = k _x ((u ₁ (t) + u ₂ (t)) / 2− (u ₁₀ + u ₂₀ ) / 2) (3)
_{y (t) = k y (} w (t) -w 0) -y 0 ··· (4)
However, the center of the foil when the vehicle is stationary is the origin, and the center P (0, y ₀ ) of the outer periphery of the foil that intersects the field of view of the line sensor is the reference position of the foil before the power performance test is performed, At this time, the position of the outer peripheral edge of the foil on the line sensor image and the distance between the outer peripheral edges of the foil are set to u ₁₀ , u ₂₀ and w ₀ (= u ₂₀ −u ₁₀ ), while the vehicle is moved. The position of the subsequent reference point P is (x, y), and the position of the outer peripheral edge of the foil and the distance between the outer peripheral edges of the foil on this line sensor image are u ₁ , u ₂ and w (= u ₂ −u as _1), the following equation transform coefficients k _x, k _y (1), was determined using (2).
k _x = x / ((u ₁ + u ₂ ) / 2− (u ₁₀ + u ₂₀ ) / 2) (1)
k _y = (y−y ₀ ) / (w−w ₀ ) (2)

Further, the present invention is a wheel position measuring device for measuring the position of a wheel of a vehicle that is installed on a roller and performs a performance test by rotating the foil,
A first line sensor that images the rotating foil, the scanning direction being a horizontal direction at a position facing the foil and a field of view intersecting the outer peripheral edge of the foil at one location; ,
A second line sensor that images the rotating foil, the scanning direction being a vertical direction at a position facing the foil and a field of view intersecting the outer peripheral edge of the foil at one point; ,
The position of the outer peripheral edge of the foil on the image acquired by the first line sensor and the position of the outer peripheral edge of the foil on the image acquired by the second line sensor are detected, and two of the detected foils are detected. Image processing means for calculating the horizontal position and the vertical position of the foil based on the position of the outer periphery ;
Tona is,
The image processing means includes
Two line sensor images are generated by arranging images taken by the first line sensor and the second line sensor in time series,
The foil trajectory on each line sensor image is extracted, and the position u _x (t) of the outer periphery of the foil on the line sensor image obtained from the first line sensor is obtained from the second line sensor. Detecting the position u _y (t) of the outer periphery of the foil on the line sensor image ,
Transform coefficient k _x, k _y and the position of the outer peripheral edge of the foil on each of the line sensor image at time t u _x (t), the following equation using the u _y (t) (7), the calculation of (8) By calculating the center position (x (t), y (t)) of the foil at time t.
x (t) = k _x (u _x (t) −u _x0 ) (7)
_{y (t) = k y (} u y (t) -u y0) ··· (8)
However, the position of the outer peripheral edge of the foil that intersects the visual field of the first and second line sensors when the vehicle is stationary with the center of the foil as the origin is x ₀ , y ₀ , and the respective line sensors at this time The position of the outer peripheral edge of the foil on the image is u _x0 , u _y0 , the position of the outer peripheral edge of the foil after moving the vehicle is x, y, and the position of the outer peripheral edge of the foil on the line sensor image at this time As u _x and u _y , conversion coefficients k _x and k _y were obtained using the following equations (5) and (6).
_{k x = (x-x 0} ) / (u x -u x0) ··· (5)
k _y = (y−y ₀ ) / (u _y −u _y0 ) (6)

In addition, the configuration of the present invention is characterized by comprising a calculation means for calculating the moving speed of the vehicle based on a change in the wheel center position (x (t), y (t)) calculated by the image processing means. To do.

Further, the configuration of the present invention is characterized by comprising a calculation means for calculating the movement acceleration of the vehicle based on a change in the wheel center position (x (t), y (t)) calculated by the image processing means. To do.

  According to the vehicle wheel position measuring device based on image processing according to the first aspect described above, the wheel position measuring device that measures the position of the vehicle wheel that is installed on the roller and performs the performance test by rotating the foil is rotated. A line sensor that images the rotating foil, with the scanning direction being set in a horizontal direction or a vertical direction at a position facing the foil and the field of view intersecting with the outer peripheral edge of the foil at two locations And detecting the outer peripheral edge of the foil on the image acquired by the line sensor, and calculating the position of the foil in the scanning direction based on the detected position of the outer peripheral edge of the foil. Since the image processing means calculates the position of the foil in the direction orthogonal to the scanning direction based on the distance between the outer peripheral edges, the non-contact In it is possible to detect the position of the wheel of the vehicle during the test running by chassis dynamometer with higher accuracy.

  According to the wheel position measuring device for a vehicle by image processing according to the second invention described above, the wheel position measuring device for measuring the position of the wheel of the vehicle that is installed on the roller and performs the performance test by rotating the foil. A first line sensor that images the rotating foil, the scanning direction being horizontal at a position facing the foil and a field of view intersecting the outer peripheral edge of the foil at one point And a second line for imaging the rotating foil, the scanning direction being a vertical direction at a position facing the foil and the field of view intersecting with the outer peripheral edge of the foil at one place. The position of the outer peripheral edge of the foil on the image acquired by the sensor and the first line sensor and the outer peripheral edge of the foil on the image acquired by the second line sensor. And image processing means for calculating the horizontal position and the vertical position of the foil based on the detected positions of the two outer peripheral edges of the foil. It is possible to detect the position of the wheel of the vehicle during the test running with the chassis dynamometer with higher accuracy by contact.

  In addition, according to the wheel position measuring device for a vehicle by image processing according to the third invention described above, a calculation means for calculating the moving speed of the vehicle based on a change in the position of the vehicle calculated by the image processing means is provided. Therefore, in addition to the effect of the first or second invention, the rotational speed of the vehicle wheel related to the test running by the chassis dynamometer can be detected with higher accuracy.

  According to the vehicle wheel position measuring apparatus using the image processing according to the fourth invention described above, the vehicle wheel position measuring apparatus includes the calculating means for calculating the movement acceleration based on the change in the position of the vehicle calculated by the image processing means. In addition to the effects of the first to third inventions, it is possible to detect the rotational acceleration of the vehicle wheel related to the test running by the chassis dynamometer with higher accuracy.

  Embodiments of the present invention will be described in detail in the following examples.

  The first embodiment of the present invention will be described in detail with reference to FIGS. FIG. 1 is a schematic configuration diagram showing an installation example of a vehicle position measuring apparatus by image processing according to the present embodiment, FIG. 2 is an explanatory diagram showing the relationship between the field of view of the foil and the line sensor in the present embodiment, and FIG. FIG. 4 is an explanatory diagram illustrating an example of a line sensor image obtained in the present embodiment, and FIG. 5 is a diagram of the vehicle position in the vehicle position measuring device according to the present embodiment. It is a flowchart which shows a calculation process.

  As shown in FIG. 1, the vehicle position measurement device based on image processing according to the present embodiment is used together with a chassis dynamometer 2 that drives a wheel 11 of a vehicle 1 under various driving conditions and performs a power performance test of the automobile. , A line sensor 3 for imaging the wheel 11 of the vehicle 1 installed on the chassis dynamometer 2, and an image processing for analyzing the image acquired by the line sensor 3 and outputting the position of the vehicle 1 during the power performance test Part 4.

  The chassis dynamometer 2 includes a roller 21 that is a rotating body provided so that the top thereof maintains substantially the same height as a floor (not shown), and a dynamometer 22 that is a power source for the rotation of the roller 21. And a chassis dynamometer (CHDY) control device 23 for controlling the torque (and speed) of the dynamometer 22. For example, when reproducing an uphill, the absorption torque is large, and when reproducing a downhill, It is configured to reproduce the actual road by reducing the absorption torque.

  The line sensor 3 is arranged at a position facing the foil 11 so that the scanning direction s shown in FIG. 2 is along the horizontal direction, and the field of view 31 intersects the outer peripheral edge of the foil 11 at two locations. . Here, it is preferable that the line sensor 3 is installed so that the visual field 31 captures an image of a substantially intermediate position between the rotation center and the upper end of the wheel 11 or between the rotation center and the lower end during the power performance test. .

Note that the alternate long and two short dashes line shown in FIG. 2B exaggerates the example when the position of the foil 11 changes. As shown in FIG. 2B, when the foil 11 moves back and forth and in the vertical direction, the positions x ₁ (t) and x ₂ (t) of the outer peripheral edge of the foil 11 in the field of view 31 of the line sensor 3 and the foil 11 It can be seen that the distance W (t) between the positions x ₁ (t) and x ₂ (t) of the outer peripheral edge changes.

The image processing unit 4, as shown in FIG. 3, an image input unit 41 to the line sensor 3 is stored in the processing memory 45 the image captured, conversion factor k _x, transform coefficient input unit 42 for inputting k _y And the position u corresponding to the positions x ₁ (t) and x ₂ (t) of the outer peripheral edge of the foil 11 on the line sensor image (see FIG. 4) obtained by arranging the images input from the line sensor 3 in time series. ₁ (t), and the wheel position detection unit 43 for detecting the u ₂ (t), conversion factor k _x, the outer peripheral edge of the position u ₁ of the foil 11 on the k _y and the line sensor image (t), u ₂ (t ) To calculate the actual position (x (t), y (t)) of the foil 11, and a processing memory 45 for storing image data, conversion coefficients, position data, and the like. .

Here, the conversion coefficient k _x, k _y is the position u ₁ of the outer peripheral edge of the foil 11 on the line sensor image shown in FIG. 4 (t), the actual position of the vehicle 1 from _{u 2 (t) (x (} t ), Y (t)) is a coefficient calculated experimentally in advance.

  Hereinafter, the flow of processing by the image processing unit 4 will be specifically described with reference to FIG. As shown in FIG. 5, first, images captured by the line sensor 3 are continuously captured by the image input unit 41 and arranged in time series to generate a line sensor image as shown in FIG. 45 (step S1).

Subsequently, the foil position detection unit 43 extracts image data from the processing memory 45, performs binarization processing or pattern matching processing on the image data, and extracts the trajectory of the foil 11 on the line sensor image. The positions u ₁ (t), u ₂ (t) on the line sensor image of the outer peripheral edge of the foil 11 at time t are detected, and the detection results are stored in the processing memory 45 as position data (step S2).

  For example, when the positions of the front and rear edges of the foil 11 are detected from the line sensor image by pattern matching processing, the locus of the foil 11 displayed on the line sensor image is registered in advance, and the registered image is shown in FIG. A portion that matches the registered image is extracted as a foil 11 by searching in the line sensor image shown, and both ends of the foil 11 on the extracted line sensor image may be detected as positions of the outer peripheral edge of the foil 11.

Subsequently, the distance conversion unit 44, and the position data from the processing memory 45 transform coefficients k _x, removed and k _y, the position of the center of the actual wheel 11 by using the position data and the transform coefficients k _x, k _y was removed Is calculated (step S3).

Incidentally, the conversion coefficient k _x, k _y, for example, actually move the vehicle 1 before performing the test runs of the vehicle 1 which is installed on the chassis dynamometer 2, and the actual amount of movement on the line sensor image It can be calculated by comparing the amount of change in the position of the outer peripheral edge of the foil 11.

That is, for example, the center of the foil 11 when the vehicle 1 is stationary is the origin, and the center P (0, y ₀ ) of the outer peripheral edge of the foil 11 that intersects the visual field 31 of the line sensor 3 is the foil 11 before the power performance test. The position of the outer peripheral edge of the foil 11 on the line sensor image and the distance between the outer peripheral edges of the foil 11 at this time are u ₁₀ , u ₂₀ and w ₀ (= u ₂₀ −u ₁₀ ). On the other hand, the position of the reference point P after moving the vehicle 1 is (x, y), and the position of the outer peripheral edge of the wheel 11 and the distance between the outer peripheral edges of the foil 11 on the line sensor image at this time are u ₁ , When u ₂ and w (= u ₂ -u _1), the conversion coefficient k _x, the k _y following formula (1) can be obtained by using (2).

k _x = x / ((u ₁ + u ₂ ) / 2− (u ₁₀ + u ₂₀ ) / 2) (1)
k _y = (y−y ₀ ) / (w−w ₀ ) (2)

In the distance conversion unit 44, k _x , k _y , positions u ₁ (t) and u ₂ (t) of the outer peripheral edge of the foil 11 on the line sensor image at time t, and on the line sensor image at time t. The foil at time t is calculated by performing the following equations (3) and (4) using the distance w (t) (= u ₂ (t) −u ₁ (t)) between the outer peripheral edges of the wheel 11 11 center positions (x (t), y (t)) can be calculated.

x (t) = k _x ((u ₁ (t) + u ₂ (t)) / 2− (u ₁₀ + u ₂₀ ) / 2) (3)
_{y (t) = k y (} w (t) -w 0) -y 0 ... (4)

  A general area camera that can capture a two-dimensional image has a sampling frequency of about 60 fps. On the other hand, the line sensor only measures a one-dimensional position, but has an advantage that it can shoot at a higher resolution and higher imaging frequency than an area camera.

  According to the present embodiment, as described above, an image obtained by imaging the foil 11 using the single line sensor 3 capable of photographing with high resolution and high imaging frequency is analyzed, and the foil 11 on the line sensor image is analyzed. The actual position of the foil 11 is calculated from the position of the outer peripheral edge of the wheel and the distance between the outer peripheral edges of the foil 11 on the line sensor image, and the power performance test is performed with a simple structure using one line sensor. It is possible to measure not only the position in one direction of the wheel 11 in the middle but also the position in two directions (in this embodiment, the front-rear direction and the vertical direction) with high performance while suppressing the cost as compared with the prior art.

  A second embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a schematic configuration diagram showing an installation example of a vehicle position measuring device by image processing according to the present embodiment, FIG. 7 is an explanatory diagram showing the relationship between the field of view of the foil and the line sensor in the present embodiment, and FIG. It is explanatory drawing which shows an example of the line sensor image obtained in FIG.

  The present embodiment differs from the vehicle position measuring apparatus according to the first embodiment shown in FIG. 1 in the configuration of the line sensor. Other configurations are substantially the same as the configurations described above with reference to FIGS. 1, 3, and 5, and hereinafter, members having the same functions are denoted by the same reference numerals, and redundant description is omitted as appropriate, and different points are mainly described. Explained.

  As shown in FIG. 6, in this embodiment, the arrangement of the line sensor (hereinafter referred to as the first line sensor) 3 is changed and a second line sensor 5 is newly provided as compared with the first embodiment. It is a thing.

  Specifically, as shown in FIG. 7, the first line sensor 3 is arranged so that the field of view 31 intersects the outer peripheral edge of the foil 11 at one place, and the second line sensor 5 is scanned. Arranged so that the line direction s is along the vertical direction and the visual field 51 intersects with the outer peripheral edge of the foil 11 at one place, images taken by the respective line sensors 3 and 5 are sometimes A line sensor image as shown in FIGS. 8A and 8B is obtained by arranging in series, and the obtained line sensor image is analyzed by the image processing unit 4 to thereby determine the position of the foil 11 during the power performance test. It is characterized by detecting.

  That is, in the present embodiment, in the image processing unit 4, the image input unit 41 stores the images input from the first and second line sensors 3 and 5 in the processing memory 45 as image data.

The foil position detection unit 43 performs binarization processing or pattern matching processing on the two image data extracted from the processing memory 45, respectively, and the foil on the line sensor image obtained from the line sensors 3 and 5, respectively. The position u _x (t) corresponding to the position x (t) of the outer peripheral edge of the foil 11 intersecting the visual field 31 on the line sensor image obtained from the first line sensor 3 is extracted. The position u _y (t) on the line sensor image corresponding to the position y (t) of the outer peripheral edge of the foil 11 intersecting the visual field 51 on the line sensor image obtained from the line sensor 5 is detected, respectively. Stored in the processing memory 45 as position data.

Then, the distance conversion unit 44, and the position data from the processing memory 45 transform coefficients k _x, removed and k _y, calculates the actual position of the wheel 11 by using the position data and the transform coefficients taken out k _x, k _y .

Incidentally, the conversion coefficient k _x, k _y in this embodiment, actually move the vehicle 1 before performing the test runs of the vehicle 1 which is installed on the chassis dynamometer 2, and the actual amount of movement, the line sensor It can be calculated by comparing the amount of change in the position of the foil 11 on the image, for example, intersecting the visual fields 31 and 51 of the line sensors 3 and 5 when the vehicle 1 is stationary with the center of the foil 11 as the origin. The position of the outer peripheral edge of the foil 11 is x ₀ , y ₀ , the position of the outer peripheral edge of the wheel 11 on each line sensor image is u _x0 , u _y0 , and the position of the wheel 11 after the vehicle 1 is moved the position of the outer peripheral edge x, y, position u _x of the outer peripheral edge of the foil 11 on the line sensor image at this time, when u _y, transform coefficients k _x, k _y by the following equation (5), (6) Can be obtained.

_{k x = (x-x 0} ) / (u x -u x0) ... (5)
k _y = (y−y ₀ ) / (u _y −u _y0 ) (6)

Then, using the above k _x and k _y and the positions u _x (t) and u _y (t) of the outer peripheral edge of the foil 11 on the respective line sensor images at time t, the following expressions (7) and (8) By calculating the above, it is possible to calculate the actual center position (x (t), y (t)) of the foil 11 at time t.

x (t) = k _x (u _x (t) −u _x0 ) (7)
_{y (t) = k y (} u y (t) -u y0) ... (8)

  According to the above-described vehicle position measurement apparatus using image processing according to the present embodiment, an image obtained by imaging the foil 11 using the two line sensors 3 and 5 capable of photographing at a high resolution and a high imaging frequency is analyzed. The actual position of the foil 11 is calculated from the position of the outer peripheral edge of the foil 11 on the line sensor image, and the two directions of the foil 11 during the power performance test (this embodiment) are calculated using two line sensors. Then, there is an advantage that the position in the front-rear direction and the vertical direction) can be measured with high performance while suppressing the cost as compared with the conventional case.

A third embodiment of the present invention will be described. This embodiment, in any of Examples 1 to 2 described above, the moving speed of the vehicle 1 based on the position data of the vehicle 1 calculated during the power performance test, and a calculating means for calculating a movement acceleration This is an example. Other configurations are the same as those described in the first and second embodiments described above, and a duplicate description is omitted.

Since this embodiment is configured to measure the position of the vehicle 1 based on the image captured by the line sensor 3 by the vehicle position measurement apparatus according to the image processing of the first or second embodiment, it is shown in FIG. In addition, the image processing unit 4 described above has been made paying attention to the fact that position data with a high sampling frequency can be obtained, and the moving speed, the moving acceleration, and the mass of the vehicle 1 during the power performance test using the position data. When is constant, the force can be calculated with high accuracy.

  The moving speed and the moving acceleration can be obtained by differentiating the position data calculated in the image processing unit 4, but since the sampling frequency of the line sensor 3 (line sensor 5) is high, the moving speed and the moving acceleration are obtained from the position data. It is conceivable that the obtained movement speed data and movement acceleration data are superimposed, making it difficult to analyze frequency events. Therefore, as shown in FIG. 9, the data at the position x (t) calculated by the image processing unit 4 is used as the calculation means by using the low-pass (LP) filter 6-1 and the band-pass (BP) filters 6-2 to 6-n. May be divided into a plurality of frequency bands, and the divided position data may be input to differentiators 7-1 to 7-n provided to correspond to the respective frequency bands.

  In the conventional structure that measures the position of the vehicle 1 at the time of the power performance test using the image captured by the area camera, it is necessary to perform image processing on a large amount of data. Although it was difficult to sample the position of the vehicle 1 in conjunction with this data, according to this embodiment, the capacity of the data can be reduced by using the line sensor 3 (line sensor 5). Since the position of the vehicle 1 can be measured with high accuracy and the processing speed in the image processing unit 4 can be improved, all data can be sampled on the same time axis, and the power performance test Can be carried out with higher accuracy.

  As described above, the present invention includes the line sensor 3 (and the line sensor 5) that images the foil 11, and the image processing unit 4 that analyzes the image captured by the line sensor 3 (and the line sensor 5). The position of the wheel 11 of the vehicle 1 during the power performance test using the chassis dynamometer 2 can be measured with high accuracy with a simple configuration.

  The present invention relates to a vehicle position and acceleration measuring device using image processing, and is particularly suitable for application to a vehicle position measuring device using image processing that measures the position and acceleration of a vehicle traveling on a chassis dynamometer.

It is a schematic block diagram which shows an example of the vehicle position measurement apparatus by the image process which concerns on Example 1 of this invention. FIG. 2A is an explanatory view showing an installation example of the foil and the line sensor in the first embodiment of the present invention, and FIG. 2B is an explanatory view showing an example of the relationship between the foil and the line sensor visual field accompanying the movement of the foil. FIG. 1 is a block diagram illustrating a schematic structure of a vehicle position measurement apparatus using image processing according to Embodiment 1 of the present invention. It is explanatory drawing which shows typically an example of the line sensor image obtained in Example 1 of this invention. It is a flowchart which shows the flow of the process in the image process part which concerns on Example 1 of this invention. It is a schematic block diagram which shows an example of the vehicle position measurement apparatus by the image process which concerns on Example 2 of this invention. FIG. 7A is an explanatory view showing an example of the installation of the foil and the line sensor in the second embodiment of the present invention, and FIG. 7B is an explanatory view showing an example of the relationship between the foil and the line sensor visual field accompanying the movement of the foil. is there. FIG. 8A is an explanatory view schematically showing an example of a line sensor image obtained from the first line sensor in the second embodiment of the present invention, and FIG. 8B is a second diagram in the second embodiment of the present invention. It is explanatory drawing which shows an example of the line sensor image obtained from a line sensor typically. It is explanatory drawing which shows the example which divides | segments position data in a frequency band in Example 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Chassis dynamometer 3,5 Line sensor 4 Image processing part 11 Wheel 21 Roller 22 Dynamometer 23 Chassis dynamometer control device 31, 51 Line sensor visual field 41 Image input part 42 Conversion coefficient input part 43 Wheel position detection part 44 Distance conversion unit 45 Processing memory

Claims (4)

A wheel position measuring device that measures the position of a vehicle wheel that is installed on a roller and rotates a foil to perform a performance test,
A line for imaging the rotating foil, the scanning direction being set in a horizontal direction or a vertical direction at a position facing the rotating foil and the field of view intersecting with the outer peripheral edge of the foil at two points. A sensor,
The outer peripheral edge of the foil is detected on the image acquired by the line sensor, and the position of the foil in the scanning direction is calculated based on the detected position of the outer peripheral edge of the foil. Image processing means for calculating a position of the foil in a direction perpendicular to the scanning direction based on a distance between the foil ,
Tona is,
The image processing means includes
A line sensor image is generated by arranging images taken by the line sensor in time series,
The locus of the foil on the line sensor image is extracted, and the positions u ₁ (t) and u ₂ (t) of the outer peripheral edge of the foil on the line sensor image at time t are detected, and the line sensor at time t is detected. Detecting the distance w (t) (= u ₂ (t) −u ₁ (t)) between the outer peripheral edges of the foil on the image;
Transform coefficient k _x, k _y and time position u of the outer peripheral edge of the foil on the line sensor image at _{t 1 (t), u 2} (t) and said at time t on the line sensor image of the foil between the outer peripheral edge of the The center position (x (t), y (t)) of the foil at time t is calculated by performing the following expressions (3) and (4) using the distance w (t). A vehicle wheel position measuring device by image processing.
x (t) = k _x ((u ₁ (t) + u ₂ (t)) / 2− (u ₁₀ + u ₂₀ ) / 2) (3)
_{y (t) = k y (} w (t) -w 0) -y 0 ··· (4)
However, the center of the foil when the vehicle is stationary is the origin, and the center P (0, y ₀ ) of the outer periphery of the foil that intersects the field of view of the line sensor is the reference position of the foil before the power performance test is performed, At this time, the position of the outer peripheral edge of the foil on the line sensor image and the distance between the outer peripheral edges of the foil are set to u ₁₀ , u ₂₀ and w ₀ (= u ₂₀ −u ₁₀ ), while the vehicle is moved. The position of the subsequent reference point P is (x, y), and the position of the outer peripheral edge of the foil and the distance between the outer peripheral edges of the foil on this line sensor image are u ₁ , u ₂ and w (= u ₂ −u as _1), the following equation transform coefficients k _x, k _y (1), was determined using (2).
k _x = x / ((u ₁ + u ₂ ) / 2− (u ₁₀ + u ₂₀ ) / 2) (1)
k _y = (y−y ₀ ) / (w−w ₀ ) (2) A wheel position measuring device that measures the position of a vehicle wheel that is installed on a roller and rotates a foil to perform a performance test,
A first line sensor that images the rotating foil, the scanning direction being a horizontal direction at a position facing the foil and a field of view intersecting the outer peripheral edge of the foil at one location; ,
A second line sensor that images the rotating foil, the scanning direction being a vertical direction at a position facing the foil and a field of view intersecting the outer peripheral edge of the foil at one point; ,
The position of the outer peripheral edge of the foil on the image acquired by the first line sensor and the position of the outer peripheral edge of the foil on the image acquired by the second line sensor are detected, and two of the detected foils are detected. Image processing means for calculating the horizontal position and the vertical position of the foil based on the position of the outer periphery ;
Tona is,
The image processing means includes
Two line sensor images are generated by arranging images taken by the first line sensor and the second line sensor in time series,
The foil trajectory on each line sensor image is extracted, and the position u _x (t) of the outer periphery of the foil on the line sensor image obtained from the first line sensor is obtained from the second line sensor. Detecting the position u _y (t) of the outer periphery of the foil on the line sensor image ,
Transform coefficient k _x, k _y and the position of the outer peripheral edge of the foil on each of the line sensor image at time t u _x (t), the following equation using the u _y (t) (7), the calculation of (8) By performing the above, the foil position measuring device by image processing is characterized in that the center position (x (t), y (t)) of the foil at time t is calculated.
x (t) = k _x (u _x (t) −u _x0 ) (7)
_{y (t) = k y (} u y (t) -u y0) ··· (8)
However, the position of the outer peripheral edge of the foil that intersects the visual field of the first and second line sensors when the vehicle is stationary with the center of the foil as the origin is x ₀ , y ₀ , and the respective line sensors at this time The position of the outer peripheral edge of the foil on the image is u _x0 , u _y0 , the position of the outer peripheral edge of the foil after moving the vehicle is x, y, and the position of the outer peripheral edge of the foil on the line sensor image at this time As u _x and u _y , conversion coefficients k _x and k _y were obtained using the following equations (5) and (6).
_{k x = (x-x 0} ) / (u x -u x0) ··· (5)
k _y = (y−y ₀ ) / (u _y −u _y0 ) (6) The calculation means which calculates the moving speed of the said vehicle based on the change of the wheel center position (x (t), y (t)) calculated by the said image processing means is provided. 3. A wheel position measuring device for a vehicle by image processing according to any one of 2 above. The calculation means which calculates the movement acceleration of the said vehicle based on the change of the wheel center position (x (t), y (t)) calculated in the said image processing means is provided. 4. A wheel position measuring device for a vehicle by image processing according to claim 1.

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