JP2008241459A - Method and apparatus for measuring road surface condition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure depth of snow by a snow depth measuring means based on a change in a recorded laser pattern position by radiating a laser pattern to a snow cover surface from slantly upward by a radiating means and recording the laser pattern radiated onto the snow cover surface by an imaging means. <P>SOLUTION: An apparatus for measuring road surface conditions includes the radiating means 1 for radiating the laser pattern L to the snow cover surface S from slantly upward, the imaging means 2 for recording the laser pattern radiated onto the snow cover surface, the snow depth measuring means 3 for measuring snow depth H based on a change in the recorded laser pattern position, an unevenness measuring means 4 for measuring an uneven state of the snow cover surface based on a shape of the recorded laser pattern and a snow quality measuring means 5 for measuring snow quality of the snow cover surface based on a change in shape of the recorded laser pattern. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a road surface condition measuring method and apparatus which are expected to be applied to the fields of road surface snow melting and traffic information systems, for example.

Conventionally, as this kind of road surface condition measuring method and apparatus, various recognition marks of a predetermined shape drawn on the road surface are illuminated with a light source, and the various recognition marks are photographed with a camera, and images of the recognition marks photographed with the camera The thing of the structure which tries to measure the condition of a road surface by image-analyzing is known.
Japanese Utility Model Publication No. 4-55557 JP2004-191276

  However, in the case of these conventional structures, it is necessary to put various recognition marks on the road surface to be measured, or to perform color image processing, and also whether the road surface is dry, wet, snowy, etc. Even if it is possible to detect, measurement of snow quality such as snow depth, snow surface unevenness, snow surface roughness and hardness when there is a lot of snow on the road surface Until then.

  The present invention aims to solve these disadvantages. Among the present inventions, the invention of the method according to claim 1 is directed to irradiating the snow surface with a laser pattern obliquely from above by means of irradiating means. The laser pattern irradiated on the surface is photographed by the imaging means, the snow depth measuring means measures the snow depth based on the change in the position of the photographed laser pattern, and based on the shape of the photographed laser pattern The road surface state measurement is characterized by measuring the uneven state of the snow surface by means of the unevenness measuring means, and further measuring the snow quality of the snow surface by the snow quality measuring means based on the change in the shape of the photographed laser pattern. Is in the way.

  According to a second aspect of the present invention, there is provided an apparatus for irradiating a snow pattern with a laser pattern obliquely from above, an imaging unit for photographing the laser pattern irradiated on the snow surface, Snow depth measuring means for measuring snow depth based on a change in position, unevenness measuring means for measuring the uneven state of the snow surface based on the shape of the photographed laser pattern, and shape of the photographed laser pattern The road surface condition measuring device comprises snow quality measuring means for measuring the snow quality of the snowy surface based on the change in the snow level.

  The invention of claim 3 is characterized in that the laser pattern is a linear line segment pattern having a line width, and the invention of claim 4 is characterized in that the line width is A laser pattern, which is a linear line segment pattern having a cross section, is irradiated in a direction intersecting with the extending direction of the road, and the invention according to claim 5 is characterized in that the snow quality measuring means comprises: As an element for grasping the snow quality of the snow surface, the roughness of the snow surface and / or the hardness of the snow surface is measured.

  As described above, in the invention according to the first aspect, the laser pattern is irradiated from the obliquely upper side to the snow cover surface by the irradiating means, and the laser pattern irradiated to the snow cover surface is photographed by the image capturing means. The snow depth is measured by the snow depth measuring means based on the change in the position of the laser pattern, and the uneven state of the snow surface is measured by the unevenness measuring means based on the photographed laser pattern shape. The snow quality of the snow surface can be measured by the snow quality measuring means based on the change in the shape of the photographed laser pattern. For this reason, the snow quality is measured in addition to the snow depth and the uneven state of the snow surface. It is possible to improve the efficiency of melting snow on the road surface and to improve the accuracy of the traffic information system.

  Further, in the invention described in claim 3, since the laser pattern is a linear line segment pattern having a line width, the measurement system is based on the influence of minute irregularities on the snowy surface compared to the spot light having a line width. And the snow depth, the uneven state of the snow surface, and the snow quality can be easily measured by image processing, and the invention according to claim 4 has the above-mentioned line width. Since the laser pattern, which is a straight line segment pattern, is irradiated in the direction that intersects the road extension direction, it is possible to capture information on snow depth, snow surface and snow quality in the cross-road direction, and traffic information The accuracy of the system can be improved, and in the invention according to claim 5, the snow quality measuring means can measure the roughness of the snow cover and / or the snow cover as an element for grasping the snow quality of the snow cover. To measure the hardness of the surface Since it is, it is possible to improve the accuracy of the traffic information system.

  1 to 9 show an embodiment of the present invention. As shown in FIGS. 1 and 2, reference numeral 1 denotes an irradiating means. In this case, the semiconductor laser irradiates a laser beam. The snow surface S is configured to be irradiated with a laser pattern L obliquely from above.

  In this case, as the irradiating means 1, one having a structure in which a laser pattern L composed of a linear line segment pattern having a line width is irradiated obliquely from above is used. As the laser pattern L, an elliptical laser pattern or the like is used in addition to the line segment pattern. However, the spot-like spot light is easily affected by minute irregularities on the snowy surface, resulting in variations in measurement systems. This is not preferable. In addition, the wavelength of the laser pattern L is preferably in the infrared region in consideration of the influence on the driver's vision.

  In this case, as shown in FIG. 2, the laser pattern L composed of a straight line segment pattern having this line width is arranged so as to irradiate in a direction intersecting the road extending direction Q.

  Reference numeral 2 denotes an image pickup means, which in this case is constituted by a camera that takes an image of the imaging region R of the laser pattern L irradiated onto the snowy surface S and outputs an imaging signal.

  Reference numeral 3 denotes snow depth measuring means. In this case, the laser pattern L photographed by the imaging means 2 is subjected to image processing to measure a change in position, and the snow depth is determined based on the change in position of the laser pattern L. Is configured to measure.

In this case, as shown in FIG. 3, when the snow surface S changes from the road surface D due to snow, the position of the laser pattern L changes from the low position L ₁ to the high position L ₂ . The change, that is, the relative relationship between the displacement of the laser pattern L and the snow depth is the relationship shown in FIG. 4. Therefore, as shown in FIG. 5, the position of the laser pattern L photographed by the imaging means 2 is processed by image processing. The change ε is measured, the snow depth H is calculated and measured based on the change ε of the position of the laser pattern L, and a position measurement signal is output.

  Reference numeral 4 denotes unevenness measuring means. In this case, the shape of the laser pattern L photographed by the imaging means 2 is measured by image processing, and the unevenness state of the snowy surface is measured based on the shape of the laser pattern. It is configured.

  In this case, as shown in FIG. 6, if the snowy surface S has irregularities, the presence of the concave portions T and the convex portions P is photographed in the shape of the laser pattern L that is originally linear, and the photographed irregularities are subjected to image processing. Based on the uneven shape of the laser pattern L, the uneven state of the snowy surface is measured and an unevenness measurement signal is output.

  Reference numeral 5 denotes a snow quality measuring means, which measures the change in the shape of the laser pattern L photographed by the imaging means 2 by image processing, and measures the snow quality on the snow surface based on the change in the shape of the laser pattern L. Is configured to do.

In this case, the roughness of the snow cover and / or the hardness of the snow cover is measured as an element for grasping the snow quality, that is, the gap S _{1 of the} snow cover S as shown in FIG. If the void ratio, which is the ratio of the snow particles S ₂ , is large and the snow surface is rough, the laser beam snow accumulation is present in the contour of the laser pattern L, for example, a linear line segment pattern having a line width. Scattered light increases in the interior, and therefore the line width of the line segment pattern increases. Conversely, as shown in FIG. 7B, the porosity of the snow cover surface S is small and the snow cover surface S is dense. In the case of the outline of the laser pattern L, for example, a linear line segment pattern having a line width, the scattered light inside the snow cover of the laser beam is reduced. For this reason, the line width of the line segment pattern is the laser beam. The line width of the laser is small, so these imaged lasers A linear regression of the luminance value of the line width of the pattern L is performed to binarize, and the obtained binarized line width intercept (Y axis) represents the average snow depth, and this binarized line width and snow cover The surface roughness is the relationship shown in FIG. 8, and the roughness and density roughness of the snow-covered surface S are calculated and measured according to the binarization line width, and a roughness measurement signal is output.

  Further, when the snow cover surface S is soft, the laser beam L has a large amount of scattered light inside the snow cover in the outline of the laser pattern L, for example, a linear line segment pattern having a line width. The line width of the line segment pattern increases, and conversely, if the snow-covered surface S is hard, the contour of the laser pattern L, for example, a linear line segment pattern having a line width, The scattered light inside the snow cover is reduced, and therefore, the line width of the line segment pattern is small and close to the line width of the laser light. Therefore, linear regression of the luminance values of the line widths of these captured laser patterns L is performed. The binarized line width and the snow surface hardness are related as shown in FIG. 9, and the snow surface hardness is calculated and measured according to the binarized line width. It is configured to output a measurement signal.

  Since this embodiment is configured as described above, the laser pattern L is irradiated to the snow cover surface S by the irradiation means 1 from obliquely above, and the laser pattern L irradiated to the snow cover surface S is photographed by the image pickup means 2 and photographed. The snow depth H is measured by the snow depth measuring means 3 based on the change of the position of the laser pattern P, and the unevenness state of the snow surface S is measured by the unevenness measuring means 4 based on the photographed laser pattern L shape. And the snow quality of the snow surface can be measured by the snow quality measuring means 5 based on the change in the shape of the photographed laser pattern L. For this reason, the snow depth H and the snow surface S can be measured. In addition to unevenness, snow quality can be measured, so that the efficiency of snow melting on the road surface and high accuracy of the traffic information system can be improved.

  In this case, since the laser pattern L is a linear line segment pattern having a line width, it is possible to suppress variations in the measurement system due to the influence of minute unevenness on the snowy surface as compared to the spot light spot. The snow depth H, the unevenness of the snow surface S, and the snow quality can be easily measured by image processing. In this case, the laser pattern L, which is a straight line segment pattern having the above-mentioned line width, is extended to the road. Since irradiation is performed in a direction crossing the direction Q, it is possible to capture information on snow depth H, snow surface S and snow quality in the direction across the road, and to improve the accuracy of the traffic information system, In this case, the snow quality measuring means 5 measures the roughness of the snow surface S and / or the hardness of the snow surface S as an element for grasping the snow quality of the snow surface. Increased accuracy It is possible.

  The present invention is not limited to the above embodiment, and the structure of the irradiation means 1, the imaging means 2, the snow depth measurement means 3, the unevenness measurement means 4, the snow quality measurement means 5 and the like are appropriately designed. Changed.

  As described above, the intended purpose can be sufficiently achieved.

1 is an overall configuration system diagram of an embodiment of the present invention. It is explanatory drawing of the use condition of the embodiment of this invention. It is an explanation side view of snow depth measurement of the embodiment of the present invention. FIG. 4 is a relationship diagram between snow depth and laser pattern displacement. It is an explanation side view of snow depth measurement of the embodiment of the present invention. It is an explanatory side view of unevenness measurement of an embodiment of the present invention. It is roughness explanatory drawing of a snowy surface. It is a relationship figure of the binary line width of a laser pattern, and the roughness of a snowy surface. It is a relationship figure of the binary line width of a laser pattern, and the hardness of a snowy surface.

Explanation of symbols

S Snow surface 1 Irradiation means 2 Imaging means 3 Snow depth measurement means 4 Concavity and convexity measurement means 5 Snow quality measurement means

Claims (5)

  A laser pattern is irradiated to the snow cover surface obliquely from above, an image of the laser pattern irradiated to the snow cover surface is taken by an image pickup means, and the snow cover is measured by a snow depth measuring means based on a change in the position of the photographed laser pattern. The depth is measured, the unevenness state of the snow surface is measured by the unevenness measuring means based on the shape of the photographed laser pattern, and the snow quality is measured based on the change in the shape of the photographed laser pattern. A road surface condition measuring method characterized by measuring the snow quality of the snow cover surface by means.   Irradiation means for irradiating the snow surface with a laser pattern obliquely from above, imaging means for photographing the laser pattern irradiated to the snow surface, and measuring snow depth based on a change in the position of the photographed laser pattern Snow depth measuring means, unevenness measuring means for measuring the uneven state of the snow surface based on the shape of the photographed laser pattern, and measuring the snow quality of the snow surface based on the change in the shape of the photographed laser pattern A road surface condition measuring device comprising snow quality measuring means.   3. The road surface condition measuring apparatus according to claim 2, wherein the laser pattern is a linear line segment pattern having a line width.   4. The road surface condition measuring apparatus according to claim 3, wherein a laser pattern, which is a linear line segment pattern having the line width, is irradiated in a direction crossing an extension direction of the road. The said snow quality measurement means measures the roughness of a snow surface and / or the hardness of a snow surface as an element which grasps | ascertains the snow quality of a snow surface, The any one of Claims 2-4 characterized by the above-mentioned. Road surface condition measuring device.

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