JPH01110237A - Road surface condition detector - Google Patents

Abstract

PURPOSE:To obtain information on readiness of slippage for a road surface in real time, by comparing a data of a known road surface with information on a road surface obtained photoelectrically. CONSTITUTION:When a projector 6 projects while light to a road surface 1, reflected light is received with a camera head 2 made up of a lens 21, a reflected light receiving element block 23 and a infrared rays receiving element block 24. The reflected light receiving element block 23 includes at least more than two light receiving elements which have a sensitivity of spectral three stimulus values as spectroscopic sensitivity of human eyes. The infrared rays receiving element block 24 includes a light receiving element for detecting radiation energy of the road surface and two light receiving elements for detecting moisture and an output thereof is introduced to a signal processor 3 which is provided with a color analysis circuit 32, a refection factor measuring circuit 33, radiation energy detecting circuit 34 and a moisture detecting circuit 35. Then, an arithmetic decision device 4 compares various signals inputted from the signal processor 3 with a data of a know road surface thereby achieving a judgement on the material and condition of the road surface.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a road surface condition detection device that can detect the condition of a road surface on which an automobile or the like is traveling and provide data necessary for driving.

(Prior Art) If data on the state of the road surface can be obtained in real time, it can be used extremely effectively as data for controlling automobile driving and braking systems.

The invention for measuring the coefficient of friction of a road surface disclosed in Japanese Patent Application Laid-Open No. 61-9365 proposes a measuring method for determining the magnitude of the coefficient of friction of a road surface by driving a vehicle.

(Problems to be Solved by the Invention) As mentioned above, there is a desire to obtain road surface data without contact without actually driving the vehicle, but no such device has been proposed.

The purpose of the present invention is to compare various already known road surface data with road surface information obtained photoelectrically to determine the road surface condition in real time, such as road surface material (asphalt concrete, gravel, etc.), road surface wetness, etc. Detects freezing, snowfall, etc. and obtains information on slipperiness (friction coefficient) based on the condition
The object of the present invention is to provide a road surface condition detection device that can obtain the following results.

(Means for Solving the Problems) In order to achieve the above object, a road surface condition detection device according to the present invention includes a light projector that projects light including a plurality of spectra onto a road surface, and a light projector that receives reflected light from the road surface. a reflected light receiving means; an infrared light receiving means for receiving an infrared component generated by the road surface; a color analysis circuit for analyzing and outputting the color of the road surface from the output of the reflected light receiving means; a moisture detection circuit that detects moisture on the road surface from the output of the light receiving means and outputs the detected moisture; a radiant energy measurement circuit that measures and outputs the radiant energy of the road surface from the output of the infrared light receiving means; a data table in which the emissivity corresponding to the road surface, the color range corresponding to the road surface material, the road surface friction coefficient corresponding to the road surface material and condition are stored in association with each other; and the presence or absence of moisture and the data table. The temperature of the road surface is calculated from the emissivity of It consists of a central processing unit that calculates the coefficient of friction of the road surface based on the state of the material and surface by referring to the data table, and an output device that outputs the calculation results of the central processing unit.

The road surface material can be classified into gravel, asphalt, concrete, and others.

Furthermore, the surface condition of the road surface can be classified into dry, wet, and frozen conditions.

(Example) The present invention will be described in more detail below with reference to the drawings and the like.

FIG. 1 is a block diagram showing a first embodiment of a road surface condition detection device according to the present invention.

The camera head 2 includes a condensing lens 21 provided in a housing (dark box) 22 and a road surface 1 condensed by this lens 21.
The infrared light receiving element group 23 and the infrared light receiving element group 24 receive reflected light from the infrared rays.

The condensing optical system including the lens 21 is provided with focusing and aperture functions.

Note that during infrared detection, it may be necessary to detect infrared rays with long wavelengths in order to eliminate infrared absorption of carbon dioxide gas, water vapor, etc., the influence of sunlight, etc., or to measure low temperature regions. Since the lens glass does not transmit infrared rays having a wavelength of 4.8 μm or more, in such a case, it is necessary to use a reflective optical system and provide a separate optical system for infrared rays.

The projector 6 is a projector that projects light including a plurality of spectra, white light in this embodiment, from the automobile toward the road surface 1.

The reflected light receiving element group 23 is formed of elements having different spectral characteristics that receive reflected light components of the white light projected toward the road surface 1 by the light projector 6.

That is, the spectral tristimulus values Maλ (long wavelength side peak of X), Tλ, which are the spectral sensitivities of the human eye.

It includes at least three or more light receiving elements each having a sensitivity of Tλ.

FIG. 2 is a graph showing a spectral sensitivity curve.

The infrared light receiving element group 24 includes a light receiving element for detecting road surface radiant energy and two light receiving elements for detecting moisture.

The outputs of the reflected light receiving element group 23 and the infrared ray receiving element group 24 are connected to the signal processing device 3.

The signal processing device 3 includes a color analysis circuit 32, a reflectance measurement circuit 33, a radiant energy detection circuit 34, and a moisture detection circuit 35.
is provided.

The color analysis circuit 32 receives the output of each element of the visible light receiving element group 23 whose wavelength sensitivity is adjusted to the tristimulus values, and calculates the color (hue) of the road surface 1 by processing the data of the tristimulus values. , brightness, saturation) and output.

The signal from the reflected light receiving element group 23 is also sent to a reflectance measuring circuit 33, and the reflectance of the road surface is measured.

The radiant energy detection circuit 34 processes signals from the infrared receiving element group 24 that detects infrared energy from the road surface 1 and outputs radiant energy data.

It is well known that infrared rays are emitted from objects in proportion to their temperature and emissivity.

As mentioned above, since water absorbs infrared rays, data on the presence or absence of moisture on the surface of the road surface 1 can be obtained using this fact.

Infrared rays from the road surface 1 are received by two moisture detection light receiving elements of the infrared light receiving element group 24.

One of the elements is made insensitive to the wavelength band absorbed by water molecules by a filter or the like.

By comparing the electric signals of the two elements with the moisture detection circuit 25, it is possible to detect the presence or absence of water on the road surface. It is also conceivable that the one of the two light-receiving elements that is sensitive to the moisture absorption band also serves as the temperature-measuring light-receiving element.

Judgment of the substance and condition of the road surface is performed by the calculation/judgment device 4 based on various signals inputted from the signal processing device.

The calculation/judgment bag W4 is provided with a central processing unit (CPU) 4L buffer memory 42 and a data table 43 for performing calculation comparisons and the like in a procedure described later.

The buffer memory 42 stores data on the process of calculation, data on the results of judgment, etc. for subsequent calculations or output.

The data table 43 stores emissivity data corresponding to road moisture, color range data corresponding to road surface materials, and road surface friction coefficient data corresponding to road surface materials and conditions, and can be called up as appropriate. is referenced.

This calculation/judgment device 4 calculates the road surface material (asphalt concrete, gravel, etc.), road surface wetness, and freezing.

The snow cover state is determined, the friction coefficient of the corresponding road surface is determined, and data for necessary display is stored in the buffer memory 42. The contents are then output or displayed by the output device 5.

Next, the operation of the central processing unit (CPU) 41 of the calculation/judgment device will be explained in detail with reference to the flowchart of FIG.

(Step 100) Start up the signal processing determination circuit. Power is supplied to each part, the projector 6 is activated, and necessary initialization is performed.

(Step 101) Referring to the output of the moisture detection circuit 35, it is determined whether there is a certain amount of moisture on the road surface or more, no moisture, or an intermediate level.

When the road surface is in an intermediate state where it cannot be said whether there is moisture or not, the process proceeds to the next step 102.

(Step 102) The output of the reflectance measurement circuit 33 is referred to to determine whether the reflectance of the road surface is high or low.

If the reflectance of the road surface is high, it is determined that there is a considerable amount of moisture.

If it is determined in step 101 that there is sufficient moisture on the road surface, or if the moisture state of the road surface is in an intermediate state in step 101, but it is determined in step 102 that the reflectance of the road surface is high, step Proceed to step 103.

(Step 103) Data indicating that there is moisture on the road surface is stored in the buffer memory 42 that records the state of the road surface.

(Step 104) Data on the standard emissivity of a wet road surface is extracted from the data table 43 and input into the buffer memory 42.

(Step 105) The road surface temperature T is calculated from the road surface radiant energy Q obtained by the radiant energy detection circuit 34 and the emissivity e extracted in step 104.

Here, the algorithm for calculating the road surface temperature T is as follows: Q: Radiant energy e: Emissivity σ: 5.675xlQ-2 (Step 106) The road surface temperature calculated at step 105 is 0°C. Compare whether it is below or above 0°C. As a result, if the temperature is 0° C. or lower, the process proceeds to step 107.

(Step 107) When the temperature of the road surface is 0° C. or lower, data indicating that the road surface is frozen or packed with snow is input into the buffer memory 42 indicating the road surface condition.

(Step 108) Data on the friction coefficient of the standard frozen road is extracted from the table 43, and display data indicating the friction coefficient of the road surface is input into the buffer memory 42.

(Step 109) If it is determined in step 106 that the temperature of the road surface exceeds 0°C, data indicating that the road surface is "wet" is input into the buffer memory 42.

(Step 1) 0) This step exists only in the second embodiment, which will be described later, so its explanation will be omitted and the process will proceed to Step 1) 1.

(Step 1) 1) Determine from the output of the color analysis circuit 32 whether the road surface is gravel, asphalt, concrete, or something else by referring to the data in the table.

(Step 1) 2) If it is determined in step 1) 1 that the road is a gravel road, the standard coefficient of friction for a wet gravel road is read from the table 43 and input into the buffer memory 42.

(Step 1) 3) If it is determined in step 1) 1 that the road surface material is asphalt, the standard friction coefficient of wet asphalt is similarly read out from the table 43 and input into the buffer memory 42. do.

(Step 1) 4) Similarly, if it is determined that the road surface is wet concrete, the standard friction coefficient of a wet concrete road surface is input into the buffer memory 42.

(Step 1) 5) Furthermore, the coefficient of friction corresponding to other substances is planned.

(Step 1) 6) If it is determined in steps 101 and 102 that there is very little moisture on the road surface, data indicating that there is no moisture on the road surface is input into the buffer memory 42 that records the condition of the road surface.

(Step 1) 7) Load the standard emissivity data of a dry road surface from the table 43 into the buffer memory 42.

(Step 1) 8) Calculate the temperature of the road surface using the same algorithm as in step 105 described above.

(Step 1) 9) Once the road surface temperature has been calculated, it is determined whether the temperature is below 0°C or above 0°C in the same manner as in step 106.

(Step 120) If the temperature is determined to be below 0°C in step 1) 9, data is stored in the buffer memo IJ42 and outputted to enable display that the road surface is frozen and caution is required. A display is made on the device 5 or another display section.

(Step 121) This step exists only in the device of the second embodiment, so its explanation will be omitted here.

(Step 122) Compare the contents of the color analysis circuit 32 with the color table,
Whether the road surface material is gravel or asphalt.
Determine whether it is concrete.

(Step 123) If it is determined that the road is a gravel road, the standard coefficient of friction for a dry gravel road is extracted from the table 43 and input into the buffer memory 42.

(Step 124) If it is determined that it is asphalt, the friction coefficient of dry asphalt is similarly taken out from the table and input into the buffer memory.

(Step 125) If it is determined that the concrete is dry, the coefficient of friction of the dry concrete is taken out from the table and input into the buffer memory.

(Step 126) Furthermore, coefficients of friction corresponding to other substances are determined.

(Step 127) When the input of friction coefficient data is completed in any of steps 108.1)2 to 1)5.123 to 125, one determination process is ended here.

The output device 5 can display the coefficient of friction input in this way, or display a warning such as whether the road surface is frozen or wet.

FIG. 3 is a block diagram showing a second embodiment of the road surface condition detection device according to the present invention.

Since this embodiment has the same main parts as the embodiment previously described with reference to FIG. 1, the explanation will focus on the different parts.

In addition to the reflected light receiving element group 23 and the infrared ray receiving element group 24 of the first embodiment, the camera head section 2 is further provided with a CCD image pickup element 25.

The output of this image sensor 25 is connected to an image processing circuit 36 of the signal processing device 3.

The image processing circuit 36 processes the output of the image sensor 25 and calculates the roughness of the road surface.

Next, the differences in the operation and determination operation of this embodiment from those of the first embodiment will be explained with reference to FIG.

In this second embodiment, step 109 is followed by step 1.
) 0, Step 1) Step 121 is entered after 9 and 120.

(Step 1) 0) When the image processing circuit 36 is checked and it is determined that the road surface is rough, it is immediately determined that it is a gravel road, and the process proceeds to Step 1) 2.

If the road surface is not rough, the substance of the road surface is determined from the color in step 1) 1, similar to the first embodiment.

(Step 121) Step 1) Next to 9.120, the image processing circuit 36 is checked, and if it is determined that the road surface is rough, it is immediately determined that it is a gravel road, and the process proceeds to Step 1) 2, where the road surface is not rough. In this case, the material on the road surface is determined from the color in step 1) 1, as in the first embodiment.

(Effects of the Invention) As described in detail above, the road surface condition detection device according to the present invention uses a projector to receive reflected light from the road surface by the reflected light receiving means, and also receives reflected light from the road surface by using the infrared light receiving means.
By receiving the infrared component generated by the road surface, information about the road surface can be obtained by non-contact photoelectric means.

Moreover, by using the photoelectric means, data can be obtained even when the vehicle is not running and regardless of the speed of the vehicle.

The data obtained in this way is compared with already known data on various road surfaces to determine the condition of the road surface in real time, such as road surface materials (asphalt, concrete, etc.).
gravel, etc.), wet and frozen road surfaces.

It is possible to detect snow accumulation, etc. and obtain corresponding friction data.

The driver can obtain information on slipperiness from this data and drive safely.

The data can also be used as a control signal for the braking system.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of a road surface condition detection device according to the present invention. FIG. 2 is a graph showing a spectral sensitivity curve for explaining the characteristics of the visible light receiving element group. FIG. 3 is a block diagram showing a second embodiment of the road surface condition detection device according to the present invention. FIG. 4 is a flowchart showing the operation of the central processing unit of the signal processing determination circuit. 1... Road surface 2... Camera head 3.
...Signal processing device 4...Calculation determination device 5...
Output device 6... Light emitter 21... Focusing lens 22... Housing (dark box) 23... Reflected light receiving element group 24... Infrared receiving element group 25... Image pickup device (COD) 32... Color analysis circuit 33... Reflectance measurement circuit 34... Temperature measurement circuit 35... Moisture detection circuit 3
6... Image processing circuit 41... Central processing unit (CPU) 42... Buffer memory 43... Data table

Claims (3)

[Claims] (1) a projector that projects light including a plurality of spectra onto a road surface, a reflected light receiver that receives reflected light from the road surface, and an infrared light receiver that receives infrared components generated by the road surface; a color analysis circuit that analyzes and outputs the color of the road surface from the output of the reflected light receiver; a moisture detection circuit that detects and outputs moisture on the road surface from the output of the infrared light receiver; A radiant energy measuring circuit that measures and outputs the radiant energy of the road surface from the output of the light receiving means, an emissivity corresponding to moisture on the road surface, a color range corresponding to the material of the road surface, and a radiant energy measuring circuit corresponding to the material and condition of the road surface. The temperature of the road surface is calculated from a data table in which the coefficient of friction of the road surface is stored in correspondence, the presence or absence of moisture, and the emissivity of the data table, and the presence or absence of a frozen state of the surface is determined from the temperature of the road surface. and a central processing unit that refers to the data table from the output of the color analysis circuit to determine the material of the road surface, and calculates the coefficient of friction of the road surface by referring to the data table from the material of the road surface and the condition of the surface. , a road surface condition detection device comprising an output device that outputs calculation results of the central processing unit. (2) The road surface condition detection device according to claim 1, wherein the road surface material is classified into gravel, asphalt, and concrete. (3) The road surface condition detection device according to claim 1, wherein the surface condition of the road surface is dry, wet, or frozen.