JP3438368B2 - Road surface condition detection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can detect the condition of the road surface of an automobile or the like to detect a warning to the driver and data necessary for a braking operation of an antilock braking system or the like. The present invention relates to a road surface state detecting device.

[0002]

2. Description of the Related Art FIG . 32 is a diagram showing a conventional road surface condition disclosed in, for example, Japanese Patent Publication No. 5-69011. In the figure, 100 is an imaging means, 101 is an image processing means, 10
2 is a comparison / determination means, 103 is a road surface state storage means, and 104 is
Is a friction coefficient storing means for the road surface, and 105 is a friction coefficient selecting means.

The above-mentioned publication is intended to detect the road surface condition in the traveling direction without bringing the detector into contact with the road surface.

The operation will be described. First, the image pickup means 1
00 captures the road surface condition in the traveling direction.
The video signal obtained from the image pickup means 100 is separated into R, G, B signals by the image processing means 101. The road surface condition storage means 103 stores various road surface conditions as a distinguishable map in the coordinates composed of R, G, B signals, and compares them with the R, G, B signals obtained from the image processing means 101. To select the type of road surface. Next, the friction coefficient of the selected road surface is selected from the friction coefficient selecting means 104 in which the friction coefficient of the road surface is stored for each selected road surface condition.

[0005]

The conventional road surface condition detecting device detects the kind of road surface by the information of the color of the road surface. Therefore, in the case of an almost achromatic road surface such as asphalt, there is a problem that it is difficult to determine whether or not the road surface is wet.

Further, there is a problem in that the result is easily influenced by the color temperature of the photographing condition and the white balance function of the image pickup device.

The present invention has been made in order to solve the above-mentioned problems. Even if the road surface is achromatic, the road surface condition such as whether or not the road surface is wet with a simple circuit structure can be determined. An object of the present invention is to obtain a road surface condition detecting device that can detect the road surface condition.

[0008]

[0009]

According to a first aspect of the present invention, there is provided a road surface state detecting device, an image pickup means for picking up an image of a road surface, a sampling means for sampling a luminance signal obtained from the image pickup means, and sampling data. Means for obtaining the average value of, the means for holding the average value in the next several fields, means for obtaining the difference between the held average value and each sampling data, and means for integrating the difference between the average value and the sampling data, Comparing means for comparing the integrated value with a predetermined constant.

Further, the road surface state detecting apparatus according to claim 2 of the present invention has an image pickup means for picking up an image of the road surface, a sampling means for sampling a luminance signal obtained from the image pickup means, and sampling data. It is composed of means for obtaining a difference from a first constant, means for integrating a difference between the sampling data and the first constant, and comparing means for comparing the integrated value with a predetermined second constant. It is a thing.

According to a third aspect of the present invention, there is provided a road surface state detecting device, an image pickup means for picking up an image of a road surface, a sampling means for sampling a luminance signal obtained from the image pickup means, and a maximum sampling data. A means for selecting a value, a means for selecting the minimum value of sampling data, a means for obtaining a difference between the maximum value and the minimum value, and a comparison for comparing the difference between the maximum value and the minimum value with a predetermined constant. And means.

According to a fourth aspect of the present invention, there is provided a road surface state detecting device, an image pickup means for picking up an image of a road surface, a sampling means for sampling a luminance signal obtained from the image pickup means, and a high luminance part in the sampling data. Means for selecting only the data of, and obtaining the average value of the high brightness portion,
Means for selecting only the data of the low-brightness portion and obtaining an average value of the low-brightness portion, means for obtaining a difference between the average value of the high-brightness portion and the average value of the low-brightness portion, and a constant for presetting the difference. And a comparison means for comparing with.

A road surface condition detecting apparatus according to a fifth aspect of the present invention is the road surface condition detecting apparatus according to any one of the first to fourth aspects, wherein a plurality of predetermined constants to be compared by the comparing means are provided. , The intensity distribution of the luminance signal is detected.

According to a sixth aspect of the present invention, the road surface state detecting device has an imaging means for imaging the road surface, a sampling means for sampling a luminance signal obtained from the imaging means, and sampling data set in advance. It is composed of a unit for dividing each constant, a histogram generating unit for converting the sampling data divided into the plurality of levels into a histogram, and a determining unit for determining the shape of the histogram.

Further, a road surface state detecting device according to a seventh aspect of the present invention is the road surface state detecting device according to any one of the first to sixth aspects, in which illumination light from the illumination means is reflected on a road surface and reflected. An incident angle that is an angle formed by the illuminating means and a normal line of the road surface so that most light is incident on the imaging device,
The illuminating means and the image pickup device are installed so that the light receiving angle, which is the angle formed by the image pickup device and the normal line of the road surface, becomes equal.

Further, a road surface state detecting device according to an eighth aspect of the present invention is the road surface state detecting device according to the seventh aspect ,
In order to prevent the illumination means and the imaging device from being affected by external light,
It is installed at the bottom of the car.

A road surface condition detecting apparatus according to a ninth aspect of the present invention is the road surface state detecting apparatus according to any one of the first to seventh aspects, in which the luminance signal is detected by the sampling means for sampling the luminance signal. The configuration is such that only the portion where the road surface is expected to be imaged is sampled.

A road surface condition detecting apparatus according to a tenth aspect of the present invention is the road surface state detecting apparatus according to any one of the first to seventh aspects, wherein only the road surface portion is detected from the imaged video signal. Means is provided and only the detected road surface portion is sampled.

[0019]

[0020]

In the road surface condition detecting apparatus according to the first aspect of the present invention, the average value of the sampled luminance signals is calculated, the difference between the average value and each sampling data is integrated, and the comparison means is used. The road surface state is determined by comparing the integrated value with a predetermined constant and detecting the intensity distribution of the luminance signal.

Further, in the road surface state detecting device according to the second aspect of the present invention, the difference between the value of the sampled luminance signal and the predetermined first constant is obtained, and the sampling data and the first constant are obtained. The road surface state is determined by integrating the difference between and, and comparing the integrated value with a predetermined second constant by the comparison means to detect the intensity distribution of the luminance signal.

Further, in the road surface state detecting device according to claim 3 of the present invention, the maximum value and the minimum value of the sampled luminance signal values are selected, and the difference between the maximum value and the minimum value is obtained, The state of the road surface is determined by comparing the difference between the maximum value and the minimum value with a predetermined constant by the comparison means and detecting the intensity distribution of the luminance signal.

Further, in the road surface state detecting device according to the fourth aspect of the present invention, in the sampled luminance signal values, only the data of the high luminance portion and the low luminance portion are selected and the average value of each is obtained. , The difference between the average value of the high-brightness portion and the average value of the low-brightness portion, the comparison means, by comparing the difference with a predetermined constant, by detecting the intensity distribution of the luminance signal, the state of the road surface To determine.

Further, in the road surface state detecting device according to a fifth aspect of the present invention, in the invention of the first to fourth aspects, the calculating means compares with a plurality of constants to detect the intensity distribution of the luminance signal. By doing so, the state of the road surface is determined.

Further, in the road surface state detecting device according to the sixth aspect of the present invention, the sampled luminance signal is divided into predetermined constants, the divided sampling data is made into a histogram, and the shape of the histogram is determined based on the shape of the histogram. The state of the road surface is determined by detecting the intensity distribution of the brightness signal.

According to a seventh aspect of the present invention, there is provided the road surface state detecting device according to any one of the first to sixth aspects, wherein the illumination light from the illumination means for illuminating the road surface is the road surface. Is reflected by the laser beam and is incident on the image pickup device.

According to an eighth aspect of the present invention, in the road surface state detecting device according to the seventh aspect , since the lighting means and the image pickup device are attached to the bottom of the automobile, other than the lighting means. Not affected by outside light.

Further, in the road surface condition detecting apparatus according to claim 9 of the present invention, the road surface condition detecting apparatus according to any one of claims 1 to 7, by the sampling means for sampling the luminance signal, the luminance signal Inside, only the part where the road surface is expected to be imaged is selectively extracted.

A road surface condition detecting apparatus according to a tenth aspect of the present invention is the road surface state detecting apparatus according to any one of the first to seventh aspects, in which only the road surface portion is detected from the imaged video signal. By means of the means, only the detected road surface portion is selectively extracted.

[0030]

【Example】

Example 1. FIG. 1 is a diagram showing a road surface state detecting device according to a first embodiment of the present invention. In the figure, 1 is an imaging device, 2
Is an A / D converter, 3 is an average value calculation circuit, 4 is an adder, 5 is an integration circuit, and 6 is a comparator.

The operation of the road surface condition detecting device configured as described above will be described. The imaging device 1 is installed at a position where the road surface can be imaged. The brightness signal obtained from the image pickup apparatus 1 is converted into a digital signal by the A / D converter 2. The A / D converter 2 has n fields (n
= 1, 2, 3 ...), m pieces of data are sampled from the luminance signal. The sampling data is input to the average value calculation circuit 3, and the average value of the sampling data is obtained.

The average value calculation circuit 3 can be realized by the following configuration, for example. FIG. 2 is a diagram showing a specific configuration of the average value calculation circuit 3 in FIG. In the figure, 11 is an integrating circuit for integrating m pieces of sampling data, 12 is a divider, and 13 is a latch. The integrating circuit 11 integrates all the sampling data. The integrated result is divided by the number of sampling data m by the divider 12 to obtain the average value of the sampling data. If the sampling data number m is a multiple of 2, the integration result is log ₂ m bits without using the divider 12.
It goes without saying that if bit shifting is performed, the average value can be similarly obtained. As described above, the average value is calculated for every n fields, and the latch 13 outputs the obtained average value k until the average value of the sampling data after the next n fields obtained by the same calculation as described above is sent. Hold for n fields.

The adder 4 subtracts, from each sampled data, the average value obtained from the sampled data n fields before, which is held by the average value calculation circuit 3. The integrating circuit 5 integrates the absolute value of the subtraction result every n fields and outputs the integrated value to the comparator 6.

FIG. 3 is a diagram showing an example of a luminance signal when photographing a dry road surface, and FIG. 4 is a diagram showing an example of a luminance signal when photographing a wet road surface. Usually, the road color is close to achromatic, as represented by asphalt. In addition, as shown in FIG. 3, the brightness value of a road surface of which the material forming the road surface is nearly uniform has a substantially constant value. An example of the intensity distribution of the luminance signal corresponding to the luminance signal waveforms of FIGS. 3 and 4 is shown in FIGS. 5 and 6. 5 and 6, the horizontal axis represents the brightness signal value representing the intensity of the brightness signal, and the vertical axis represents the sampling number of the brightness signal digitally converted by the A / D converter 2. As shown in FIG. 3, when the road surface is dry, the fluctuation range of the luminance signal is small. Therefore, the variance of the intensity distribution of the luminance signal becomes small as shown in FIG.

However, when the road surface gets wet, the wet road surface reflects outside light such as sunlight and lighting due to the flattening of the road surface by water, but the image signal from the image pickup device 1 is strongly reflected. On the contrary, a part where the reflected light is weak occurs. That is, the variation rate of the luminance signal becomes larger. FIG. 6 is the intensity distribution of the luminance signal shown in FIG. 4. Since the fluctuation rate of the luminance signal is larger than that when the road surface is dry, the variation of the luminance signal when the road surface shown in FIG. 5 is not wet. Clearly different from the value. FIG. 7 is a diagram showing the relationship between the state of the road surface and the integral value. As shown in the figure, as the road surface gets wet, the integral value becomes larger and a predetermined constant k
When the integrated value exceeds the constant k, it can be determined that the road surface is wet.

In the circuit configuration, a predetermined constant k is compared with the comparator 6, and the integrated value is the constant k.
If it is smaller, it is determined that the road surface is not wet.

Further, although the road surface state detecting device performs the subtraction with the sampling data by holding the average value by the latch 13 for n fields, it has a storage means capable of holding the sampling data for n fields regardless of the above means. By doing so, it can also be realized by holding the sampling data in the storage means during the n field period in which the average value is obtained, and subtracting the obtained average value from the held sampling data.

Furthermore, the luminance signal is sampled by n
Although the sampling is performed for each field, the sampling interval is not limited to the above, and it can be realized by sampling n fields every few fields.

Example 2. FIG. 8 is a diagram showing a road surface state detecting device according to the second embodiment of the present invention. In the figure, 15
Is an automatic gain control circuit that changes the gain so that the luminance signal has a constant level. 1 to 6 are the same as the circuit shown in FIG. 1, and the description thereof will be omitted.

The operation of the road surface state detecting device constructed as described above will be described. The luminance signal obtained from the image pickup apparatus 1 is input to the automatic gain control circuit 15. The automatic gain control circuit 15 controls the gain so that the level of the input luminance signal becomes a constant value. Similar to the first embodiment, the A / D converter 2 samples the luminance signal every n fields and outputs the sampling data to the adder 4. When the luminance signal value of the video signal level converged by the automatic gain control circuit 15 is k2, k2 is provided in advance in the adder 4 as a constant, and the adder 4 subtracts k2 from each sampling data, and the difference is calculated. Output to the integrating circuit 5. The integrating circuit 5 integrates the absolute value of the difference between each sampling data and k2 for every n fields. The comparator 6 is
The integrated value obtained from the integrating circuit 5 is compared with a predetermined constant k as in the first embodiment. When the integrated value is smaller than k, it is determined that the road surface is not wet, and when it is larger than k, it is determined that the road surface is wet.

In the present invention, since the automatic gain control circuit 15 is provided, the constant k2 is provided in advance in the adder 4 without providing the means for obtaining the average value of the luminance signal values as in the first embodiment. The same effect can be obtained.

Example 3. FIG. 9 is a diagram showing a road surface state detecting device according to the third embodiment of the present invention. In the figure, 20
Is a maximum value detecting means for detecting the maximum value of the sampling data, and 21 is a minimum value detecting means for detecting the minimum value of the sampling data. 1 to 6 are the same as the circuit shown in FIG. 1, and the description thereof will be omitted.

The operation of the road surface condition detecting device constructed as described above will be described. The process up to sampling data from the luminance signal by the A / D converter 2 is the same as that in the first embodiment, and the description thereof is omitted. The maximum value detecting means 20 detects the maximum value Ymax from the sampling data of one field. Further, the minimum value detecting means 21 detects the minimum value Ymin from the sampling data of one field. The adder 4 calculates the difference between the maximum value and the minimum value Ymax-Ymin.
Is output to the comparator 6.

As described in the first embodiment, there is a difference in luminance signal between when the road surface is dry and when the road surface is wet, as shown in FIGS. 3 and 4. Therefore, as shown in FIG. 10, since the difference Ymax-Ymin between the maximum and minimum values of the sampling data when the road surface is wet and the difference between the maximum value and the minimum value when the road surface is dry are different, Figure 1
As shown in 0, a constant k is set in advance and Ymax-Y
By comparing with min, it is possible to determine whether or not the road surface is wet.

The comparator 6 compares the difference Ymax-Ymin between the maximum value and the minimum value input from the adder 4 with the constant k. When the integrated value is smaller than k, it is determined that the road surface is not wet, and when it is larger than k, it is determined that the road surface is wet.

Since the road surface condition detecting apparatus according to the present embodiment detects and uses only the maximum value and the minimum value in the luminance signal, it can be realized without using the integrating circuit as in the first and second embodiments.

Example 4. 11: is a figure which shows the road surface state detection apparatus in Example 4 of this invention. In the figure, 2
5 is a high-luminance portion detection circuit, 26 is a low-luminance portion detection circuit, 27
And 28 are average value calculation circuits.

The operation of the road surface condition detecting device constructed as described above will be described. The process up to sampling data from the luminance signal by the A / D converter 2 is the same as that in the first embodiment, and the description thereof is omitted. FIG. 12 is a diagram showing a relationship between a luminance signal when a road surface is imaged and a high luminance portion detection value and a low luminance detection value. High brightness part detection circuit 25
Withdrawing the only the k3 over sampled values as shown in FIG. 12 from the sampling data. Average value calculation circuit 27
Calculates the average value Yh of the sampling data of the high luminance part by integrating only the sampling data of the high luminance part and dividing by the number of extracted data m1. Further, the minimum value detecting means 26 extracts only sampling data of k4 or less from the sampling data as shown in FIG. The average value calculation circuit 28 integrates only the sampling data of the low luminance part and divides by the number of extracted data m2 to obtain the average value Y 1 of the sampling data of the low luminance part. The adder 4 obtains a difference Yh−Y 1 between the average value of the high luminance part and the average value of the low luminance part, and outputs it to the comparator 6.

As described in the first embodiment, there is a difference in the intensity distribution of the luminance signal between when the road surface is dry and when the road surface is wet, as shown in FIGS. Therefore, as shown in FIG. 13, the difference Yh-Yl between the average value of the high brightness portion and the average value of the low brightness portion when the road surface is wet, and the average value and the low value of the high brightness portion when the road surface is dry. Since it is different from the difference Yh-Yl from the average value of the luminance part, it is possible to determine whether or not the road surface is wet by providing the constant k in the comparator 6 in advance and comparing it with Yh-Yl.

As described above, the comparator 6 compares the input difference Yh-Yl between the maximum value and the minimum value with the constant. When the integrated value is smaller than k, it is determined that the road surface is not wet, and when it is larger than k, it is determined that the road surface is wet.

Since the road surface condition detecting apparatus according to the present embodiment detects the high brightness portion and the low brightness portion in the brightness signal and uses them for the road surface condition detection, an extremely high value due to disturbance such as noise is detected in the brightness signal. It is easy to detect the variance of the intensity distribution of the brightness signal only in the high brightness part and the low brightness part without the discrimination result being affected by the unique brightness signal such as the brightness signal value that it has or the extremely low brightness signal value. It is possible to realize a highly accurate road surface state detection device.

Example 5. A plurality of constants to be compared by the comparator 6 in the first to fourth embodiments are provided. For example, in Example 1, the state of the road surface was determined by comparing the constant k with the integrated value. FIG. 14 is a diagram showing the relationship between the road surface state and the integrated value. As shown in the figure, the constant is set to k5.
A plurality of k6 and k7 are provided. The condition of the road surface is gradually "dry", "a little wet", "pretty wet", "very wet" from the dry condition to the condition where the water completely covers the road surface. Once determined, the comparator 6 determines that it is “slightly wet” when the integrated value is k5 or more, and k
When it is 6 or more, it is determined that it is “very wet”, and when it is k7 or more, it is determined that it is “very wet”. By providing a plurality of constants as described above, it is possible not only to determine whether or not the road surface is wet, but also to determine a plurality of steps for each stage.

Example 6. FIG. 15 is a diagram showing a road surface state detecting device according to a sixth embodiment of the present invention. In the figure, 3
Reference numeral 0 is a comparator for comparing the sampling data with a plurality of different values, 31 is a counter for counting the result of comparison by the comparison means, and 32 is a microcomputer for generating a histogram.

The operation of the road surface condition detecting device configured as described above will be described. The process up to sampling data from the luminance signal by the A / D converter 2 is the same as that in the first embodiment, and the description thereof is omitted.

The comparator 30 compares the sampling data with different values of V1 to V7 as shown in FIG. 16, and divides the sampling data into regions of L1 to L8.
The counter 31 counts the number of sampling data of each layer from the result of division into each area by the comparator 30. The microcomputer 32 generates a histogram of the area from L1 to L8 from the sampling data number counted by the counter 31.

17 to 19 are diagrams showing histograms depending on the wetness of the road surface. When the road surface is dry,
As described in the first embodiment, the fluctuation rate of the luminance signal level is small, and the luminance signal is automatically controlled by the automatic gain control circuit 15 so that the luminance signal level becomes constant as shown in FIG. The gain control circuit 15 concentrates on the brightness level to be converged. When the road surface begins to get wet, there are portions where the road surface is wet, portions where the road surface is not wet, and reflection of water on the road surface. Therefore, the luminance signal level has a shape as shown in FIG. Furthermore, when the road surface is wet and most of the road surface is covered with water, the brightness signal is divided into a brightness value reflected by water and a brightness value not reflected by water.
The shape of the histogram is as shown in FIG. The microcomputer 32 determines which one of the histogram shapes shown in FIGS. 17, 18 and 19 it belongs to.

As a method of detecting the histogram, for example, the sampling numbers from L1 to L8 are compared with each other. If L5 is larger than the default value k5 and the other values are farther away from L5, the sampling number is smaller than the default value k6. It is determined that the histogram is the one shown in FIG.
If all the sampling numbers from 1 to L8 are smaller than the default value k7 and larger than other numerical values, it is determined that the histogram is the one shown in FIG. 18, and if it is smaller, the histogram is shown in FIG.

FIG. 20 is a diagram showing another circuit configuration of the road surface state detecting device in the sixth embodiment of the present invention. As shown in the figure, a memory 33 is provided, and the memory 33 has an LU.
The histogram shown in FIG. 17 to FIG. 19 is stored as T, and each histogram is compared by comparing each value of the histogram obtained from the microcomputer 32 with the histogram provided in the memory 33. Can be determined to belong to.

As described above, by generating a histogram from the luminance signal and discriminating to which shape of the histogram provided in advance it is possible to detect the state of the road surface by dividing it into three states.

In the road surface state detecting method according to this embodiment,
Since the intensity distribution of the luminance signal is measured using the histogram, the discrimination result is less likely to be affected by a peculiar signal due to noise or disturbance in the obtained luminance signal, and highly accurate detection accuracy can be obtained. The preset histogram as a model is created with data obtained from the microcomputer 32 that generates a histogram by traveling on the road surface in advance, but the data obtained from the traveling road surface is set in advance. Since it is possible to easily make a change even when the data is slightly different from the previously stored histogram data, it is possible to improve the detection accuracy.

Further, in the present embodiment, three predetermined histograms are provided and it is configured to determine to which the histogram of the detected luminance signal belongs, but the predetermined histogram is 3 It is needless to say that the state of the road surface can be detected by dividing it into a plurality of states by providing a plurality of them.

Example 7. FIG. 21 is a diagram showing the arrangement of the illumination means and the imaging device in the seventh embodiment of the present invention. In the figure, 40 is an illuminating means, and 41 is an image pickup device 1 in the road surface state detecting devices of the first to sixth embodiments.

The operation of the road surface condition detecting device configured as described above will be described. Claims 1 to 6
In the present invention, the illumination means 40 is installed in the automobile so as to illuminate the road surface. The relationship between the illumination means 40 and the imaging device 41 is shown in FIG. The imaging device 41 is installed in an automobile so that the light rays emitted from the illumination means are reflected by the road surface and the reflected light rays are incident. That is, in FIG. 20, the illumination means 40 and the imaging device 41 are installed so that the incident angle θ1 and the light receiving angle θ2 are equal.

By illuminating the road surface with the illumination means 40 in this way, when the road surface is wet, water on the road surface is reflected. Therefore, in the first to sixth embodiments, the road surface is wet and the wet surface is wet. If not, the difference will be greater. For example, in the diagram shown in FIG. 7 in the first embodiment, as shown in FIG. 22, the difference between the integral value when wet and the integral value when not wet becomes large, and the determination of the road surface state becomes easier. Become.

Example 8. FIG. 23 is a diagram showing the installation positions of the illumination means and the imaging device in the eighth embodiment of the present invention. In the figure, 42 is an automobile.

The illumination means 40 and the image pickup device 41 are installed at the bottom of the automobile 42 where external light does not enter. Since the bottom of the automobile 42 is the shadow of the automobile 42 itself, sunlight or light such as street lighting does not enter. By installing as described above, the reflected light on the road surface can be imaged without being affected by the illumination other than the illumination means 40 installed in the automobile 42.

Example 9. 24: is a figure which shows the road surface state detection apparatus in Example 9 of this invention. In the figure, 4
Reference numeral 5 is a timing generator that determines sampling points of the luminance signal by controlling sampling pulses of the A / D converter 2. As an example of the present invention, FIG. 24 shows a circuit in which a timing generator 45 is provided in the circuit configuration of the first embodiment shown in FIG.

According to the image pickup apparatus 1, the road surface is shown in FIG.
An image is taken as shown in 6. In the image signal picked up as described above, the road surface portion is concentrated in a portion represented by the shaded area A in FIG. Therefore, the timing generator 45 can sample only the luminance signal of the road surface portion by generating a sampling pulse to the A / D converter 2 so as to sample only the shaded portion a.

Since the processing for detecting the state of the road surface after sampling is the same as that in the first embodiment, the description thereof will be omitted.

As described above, the timing generator 45
By providing only the luminance signal of the road surface portion, the determination accuracy can be improved without the result being influenced by the luminance signal of the scenery other than the road surface.

Also in the inventions of the second to sixth embodiments, the same effect can be obtained by including the timing generator 45.

Example 10. 28 is a tenth embodiment of the present invention.
It is a figure which shows the road surface state detection apparatus in. In the figure, reference numeral 50 is an A / D converter, and 51 is a road surface detecting means for detecting only the road surface from the imaged video signal.

The operation of the road surface condition detecting device constructed as described above will be described. A / D converter 50
Converts the luminance signal obtained from the image pickup device 1 into a digital signal. The road surface detecting means 51 detects only the road surface from the image signal picked up from the luminance signal obtained from the A / D converter 50.

The road surface detecting means 51 includes various methods such as a method of detecting using a white line on the road surface and a method of detecting an aperture component of a luminance signal by pattern matching. The road surface detecting means 51 is realized by, for example, the following configuration. be able to. FIG. 29 is a diagram showing a specific circuit configuration of the road surface detecting means 51. In the figure, reference numeral 60 denotes an edge detection circuit for extracting only the aperture component in the video signal, and 61.
Is pattern recognition means for detecting the edge of the road surface from the extracted edge component. The operation of the road surface detecting means configured as described above will be described. The edge detection circuit 60 extracts the aperture component from the video signal.

FIG. 30 is a diagram showing an output result of the edge detection circuit 60. As shown in FIGS. 25 and 26, the road surface is located in the lower center of the screen and has a substantially symmetrical shape on the left and right sides. Even when the road bends ahead, the end of the nearby road surface is shown in FIG. It exists in the frame of b. Further, the aperture component continues in a long and narrow manner, the end of the left road surface extends from the lower left of the screen to the upper right, and the end of the right road surface extends from the lower right of the screen to the upper right. The pattern recognition means 61 detects only the aperture component satisfying the above conditions from the aperture components extracted by the edge detection circuit 60. The road surface detecting means 51 regards the central portion of the screen surrounded by the detected aperture component as the road surface, as shown in C in FIG.

The road surface detecting means 51 only detects the road surface portion,
A control signal is output to the timing generator 45 so that the A / D converter 2 samples the data. For example, only the road surface portion detected by the road surface detecting means 51 is h
The above function can be realized by outputting a high pulse signal and gated so that the timing generator 45 outputs the sampling pulse signal only at the high position by the pulse signal.

Since only the road surface portion detected by the road surface detecting means 51 is sampled by the A / D converter 2 and then the road surface state is detected, the description thereof is omitted because it is the same as that of the first embodiment.

As described above, the timing generator 45
By providing the road surface detecting means 51 and only the road surface luminance signal can be accurately extracted, the discrimination accuracy can be improved without the result being influenced by the luminance signal other than the road surface.

Similarly, in the inventions of the first to sixth embodiments, the same effect can be obtained by including the timing generator 45, the A / D converter 50 and the road surface detecting means 51.

[0080]

[0081]

As is evident from the foregoing description, according to the road surface condition detecting apparatus according to claim 1 of the present invention, even the color of the road surface is a colorless, in real time, determines whether a road surface is wet It is possible to obtain a road surface condition detecting device that can be used.

According to the road surface condition detecting device of the second aspect of the present invention, in the road surface condition detecting device of the first aspect , it is possible to reduce the number of circuits for calculating the average value of the luminance signal.

According to the road surface condition detecting apparatus of the third aspect of the present invention, even if the road surface is achromatic, it is possible to determine whether or not the road surface is wet with a simple circuit configuration and real time. It is possible to obtain a road surface condition detecting device that can be used.

Further, according to the road surface state detecting device of the fourth aspect of the present invention, even if the road surface color is achromatic, it is possible to obtain peculiar data due to noise or disturbance with a simple circuit configuration and real time. It is possible to obtain a road surface state detection device that is not affected by the influence and can determine whether or not the road surface is wet.

Further, according to the road surface condition detecting apparatus of the fifth aspect of the present invention, even if the road surface color is achromatic, not only is it determined whether or not the road surface condition is wet, but also at each stage. It is possible to obtain a road surface state detection device capable of making a plurality of determinations.

Further, according to the road surface condition detecting apparatus of the sixth aspect of the present invention, since the intensity distribution of the luminance signal is measured by using the histogram, a unique signal due to noise or disturbance in the obtained luminance signal is detected. The result is unlikely to be affected, and high detection accuracy can be obtained. The preset histogram as a model is created with data obtained from the microcomputer 32 that generates a histogram by traveling on the road surface in advance, but the data obtained from the traveling road surface is set in advance. Since it is possible to easily make a change even when the data is slightly different from the data of the stored histogram, it is possible to obtain a road surface state detection device that can also improve detection accuracy.

Further, according to the road surface condition detecting apparatus of the seventh aspect of the present invention, whether the road surface is wet or not even when the road surface is not exposed to light and is not glossy due to water reflection, It is possible to obtain a road surface state detection device that can determine whether or not it is. Further, the discrimination accuracy of the road surface state detecting device according to the first to sixth aspects can be improved.

Further, according to the road surface condition detecting apparatus of the eighth aspect of the present invention, it is possible to determine whether or not the road surface is wet without being affected by the sunlight or the illumination installed on the road. A road surface condition detecting device can be obtained.

Further, according to the road surface condition detecting apparatus of the ninth aspect of the present invention, since only the brightness signal of the road surface portion is extracted and the road surface condition is determined, the result is not influenced by the brightness signal of scenery other than the road surface. A road surface condition detecting device can be obtained. Further, the discrimination accuracy of the road surface state detecting device according to the first to sixth aspects can be improved.

Further, according to the road surface condition detecting device of the tenth aspect of the present invention, since only the luminance signal of the road surface portion can be extracted more accurately than in the ninth aspect , the result can be obtained as a luminance signal of a scene other than the road surface. It is possible to obtain a road surface state detecting device that does not affect the road surface condition. In addition, claim 1 to claim
It is possible to improve the discrimination accuracy of the road surface state detection device of No. 6 .

[Brief description of drawings]

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

FIG. 2 is a diagram showing a specific configuration of an average value calculation circuit in FIG.

FIG. 3 is a diagram showing an example of a luminance signal when a dry road surface is imaged.

FIG. 4 is a diagram showing an example of a luminance signal when a wet road surface is imaged.

FIG. 5 is a diagram showing an example of an intensity distribution of a luminance signal when a dry road surface is imaged.

FIG. 6 is a diagram showing an example of an intensity distribution of a luminance signal when a wet road surface is imaged.

FIG. 7 is a diagram showing a relationship between a road surface state and an integrated value.

FIG. 8 is a diagram showing a road surface state detecting device according to a second embodiment of the present invention.

FIG. 9 is a diagram showing a road surface state detecting device according to a third embodiment of the present invention.

FIG. 10 is a diagram showing the relationship between the state of the road surface and the difference between the maximum value and the minimum value.

FIG. 11 is a diagram showing a road surface state detecting device according to a fourth embodiment of the present invention.

FIG. 12 is a diagram showing a relationship between a luminance signal when a road surface is imaged and a high-luminance portion detection value and a low-luminance portion detection value.

FIG. 13 is a diagram showing a relationship between a road surface state and a difference between an average value of a high brightness portion and an average value of a low brightness portion.

FIG. 14 is a diagram showing a relationship between a road surface state and an integrated value.

FIG. 15 is a diagram showing a road surface state detecting device according to a sixth embodiment of the present invention.

FIG. 16 is a diagram showing a relationship between a luminance signal when a road surface is imaged and a comparison value.

FIG. 17 is a diagram showing a histogram according to a wet condition of a road surface.

FIG. 18 is a diagram showing a histogram according to the degree of wetting of a road surface.

FIG. 19 is a diagram showing a histogram according to a wet condition of a road surface.

FIG. 20 is a diagram showing another circuit configuration of the road surface state detecting device according to the sixth embodiment of the present invention.

FIG. 21 is a diagram showing an arrangement of an illumination unit and an image pickup device according to a seventh embodiment of the present invention.

FIG. 22 is a diagram showing a difference in integrated value between with and without illumination.

FIG. 23 is a diagram showing installation positions of an illumination unit and an image pickup device in Embodiment 8 of the present invention.

FIG. 24 is a diagram showing a road surface state detecting device according to a ninth embodiment of the present invention.

FIG. 25 is a diagram showing an example of a video signal.

FIG. 26 is a diagram showing an example of a video signal.

FIG. 27 is a diagram showing a location of a road surface on the screen.

FIG. 28 is a diagram showing a road surface state detection device according to a tenth embodiment of the present invention.

FIG. 29 is a diagram showing a specific circuit configuration of road surface detection means.

FIG. 30 is a diagram showing an output result of the edge detecting means.

FIG. 31 is a diagram showing the detected position of the road surface.

FIG. 32 is a diagram showing a conventional road surface state detecting device.

[Explanation of symbols]

1 image pickup device, 2 A / D converter, 3 average value calculation circuit, 4 adder, 5 integration circuit, 6 comparator, 7 output terminal, 11 integration circuit, 12 divider, 13 latch, 15 automatic gain control circuit, 20 Maximum value detection means,
21 minimum value detecting means, 25 high brightness part detecting means, 26
Low-intensity part detection means, 27, 28 average value calculation circuit, 3
0 comparator, 31 counter, 32 microcomputer, 33 memory, 40 illumination means, 41 imaging device, 42 automobile, 45 timing generator, 5
0 A / D converter, 51 Road surface detection means.

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-6-307837 (JP, A) JP-A-63-82310 (JP, A) JP-A-5-347000 (JP, A) Actual development Sho-57- 94846 (JP, U) Actual Kaihei 4-55557 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01N 21/84-21/958 G01B 11/00-11/30

Claims (10)

(57) [Claims] 1. An imaging device for imaging a road surface, and an imaging device.
The luminance signal obtained from
Sampling means for sampling and the sampling
Of sampling data sampled by means
Means for obtaining the average value and the average value for the next number field
Hold for a while, and hold the average value and each sampling data
Means for obtaining the absolute value difference and a method for integrating the absolute value difference
And a comparing means for comparing the integrated value with a predetermined constant.
And the integrated value obtained by the comparison means.
By comparing with the above constant,
Detect the cloth and check whether the road surface is wet based on the detection results.
A road surface condition detecting device characterized by determining whether or not. 2. Imaging means for imaging a road surface, and imaging
So that the level of the luminance signal obtained from the means becomes constant
An automatic gain control circuit for amplifying a luminance signal, and the automatic gain control circuit
The brightness signal whose gain is controlled by the control circuit
Sampling means for sampling m pieces for each field, and
Sump sampled by the sampling means
Find the absolute difference between the ring data and the first constant
Means for integrating the absolute value difference,
Comparing means for comparing the value with a predetermined second constant
Then, in the comparison means,
By comparing with the constant of 2, the intensity distribution of the luminance signal level
And whether the road surface is wet or not based on the detection result
A road surface state detecting device characterized by determining. 3. An image pickup means for picking up an image, and an image pickup means
The brightness signals obtained from
Sampling means, and the m samplings
A means to select the maximum value of data and a method to select the minimum value.
A step, means for obtaining a difference between the maximum value and the minimum value, and
Comparing the difference with a predetermined constant,
The comparison means compares the obtained difference with the above constant.
The intensity distribution of the luminance signal level is detected by
From the output result, it is possible to determine whether the road surface is wet or not.
A characteristic road surface condition detection device. 4. Imaging means for imaging a road surface, and imaging
The luminance signal obtained from
Sampling means for sampling, and the m number of sumps
Select only the high brightness part of the ring data,
Means to obtain the average value of the brightness part and only the data of the low brightness part
Means for obtaining an average value of the low-luminance portion, and
A method to find the difference between the average value of high brightness area and the average value of low brightness area
And a comparing means for comparing the difference with a predetermined constant.
And comparing the calculated difference in the comparison means
Detect intensity distribution of luminance signal level by comparing with number
Then, from the comparison result, determine whether the road surface is wet
A road surface state detection device characterized by: 5. A predetermined constant to be compared by the comparison means is duplicated.
Number, the intensity distribution of the brightness signal is detected, and the wet condition of the road surface
Claim 1 thru / or Claim characterized by discriminating in several steps.
Item 5. The road surface condition detecting device according to any one of items 4. 6. Imaging means for imaging a road surface, and imaging
The luminance signal obtained from
Sampling means for sampling, and the m number of sumps
Means for splitting ring data into multiple levels;
The sampling data divided into several levels is
And a histogram generating means for converting the histogram
The shape is one of multiple histogram models
A discriminating means for discriminating whether
From the shape of the histogram discriminated by the steps, the luminance signal
Signal strength distribution is detected and the road surface becomes wet based on the detection results.
A road surface condition detecting device characterized by determining whether or not
Place 7. An illumination means is provided, and the illumination means
Illuminates the road surface with an angle between the lighting means and the normal to the road surface.
Angle of incidence between the imaging device and the road surface normal.
Specially, install the image pickup device so that the light angles are equal.
Road surface according to any one of claims 1 to 6
State detection device. 8. The illumination means and the image pickup device are affected by external light.
It is installed at the bottom of the car to prevent
The road surface condition detecting device according to claim 7. 9. A sampler for sampling a luminance signal.
If the road surface is imaged in the luminance signal,
Characterized by selectively extracting only the expected part
The road surface condition inspection according to any one of claims 1 to 7.
Output device. 10. Only a road surface portion is included in the captured luminance signal.
It is equipped with a road surface detection means for detecting
The feature is to selectively extract only the road surface part detected by
The road surface according to any one of claims 1 to 7, which is a sign.
State detection device .