JPH11190693A - Road surface condition determination device - Google Patents

Abstract

(57) Abstract: Provided is a road surface state determination device that detects a road surface state using road surface reflected light and can also determine that the detection state is defective. A road surface state determination device identifies a type of a road surface from a reflection intensity characteristic map with respect to light reflected from the road surface, and outputs a detection signal Mμ from a detection section to display it on a display device. On the other hand, in the determination section 40, the lens 27 is obtained from the stain determination map based on the detection signal Mμ.
Is determined, and a determination signal Dt for notifying that the detection accuracy is poor is output and displayed on the display device 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road condition judging device for judging the condition of a road surface on which a vehicle travels by using an optical method, and more particularly, to knowing that the judgment accuracy is poor. The present invention relates to a road surface condition determination device that can be used.

[0002]

2. Related Background Art For example, Japanese Patent Publication No. 3-30116 discloses a distance measuring apparatus using an optical method for obtaining a distance to an object to be measured based on reflected light from the object to be measured. . This known distance measuring device includes an optical unit for measurement composed of a light emitting device and a light receiving device stored in a case, and a light receiving unit for detecting dirt in the case. Specifically, when light is transmitted from the light emitter of the measuring optical unit to the device under test through the light transmitting window formed in the case, the scattered light from the cover provided in the light transmitting window Is detected by the dirt detection light receiving unit, and dirt and the like attached to the cover are detected based on the intensity of the scattered light.

Therefore, according to the above distance measuring device,
It is conceivable that it is possible to know that the detection accuracy of the optical unit for measurement is also reduced in proportion to the degree of the detected dirt.

[0004]

However, since a known distance measuring device uses a dirt detecting light receiving unit in addition to a commonly used measuring optical unit, the light receiving signal is processed to determine dirt and the like. In addition, an extra judgment circuit is required. The present invention has been made based on the above-described circumstances, and the object thereof is to:
It is an object of the present invention to provide a road surface state determination device which can confirm that the detection accuracy has been reduced only by a main optical unit without providing an additional optical unit.

[0005]

According to a first aspect of the present invention, there is provided a road surface condition determining apparatus for detecting a road surface condition based on reflection intensity characteristics of vertical and horizontal polarization components of light reflected from a road surface by a detecting means. Is detected and a detection signal is output, and based on the detection signal, the detection failure state of the detection means is determined by the determination means.

According to the first aspect of the present invention, the road surface on which the vehicle travels is determined based on the reflection intensity characteristics of the vertical and horizontal polarization components of the reflected light, such as a dry road, a wet road or a snowy road. State is detected. At this time, if the detection signal is output in a region where the reflection intensity of the vertical and horizontal polarization components is extremely low, it is determined that the detection state of the detection unit is defective.

Preferably, even if the result of detection by the detecting means is a dry path, if the reflection intensity of the vertical and horizontal polarization components is in a region lower than the level obtained on a normal dry path, transmission and reception are performed. It is considered that a defect such as adhesion of dirt on the lens surface has occurred. The road surface condition determination device according to claim 2 detects the operation state of the vehicle equipment used at the time of rainfall or snowfall by the detection means, and determines the detection failure state based on the detection signal and the road surface state detection signal.

According to the second aspect of the present invention, when the road surface condition during rainfall or snowfall is not detected by the detecting means in spite of rainfall or snowfall, the detection state is poor. Is determined. More preferably, when the road surface state is not detected as a wet road or a snowy road by the detection means even when the window wiper is operated during rainfall or snowfall, for example, the detection is performed by the dirt on the light transmitting and receiving lens surface described above. It is determined that the state is bad.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a road condition judging device will be described below. Referring to FIG. 1, a vehicle 2 equipped with a road surface condition determination device according to one embodiment is shown. Vehicle 2
A display device 4 for displaying a road surface condition on an instrument panel is disposed in the passenger compartment of the vehicle.
Is supplied with a road surface state detection signal output from an electronic control unit (ECU) 6. Display device 4
Is displayed on the display surface on the basis of the detection signal. Note that the ECU 6 is arranged at an appropriate position in the vehicle 2.

A sensor signal is supplied from the road surface sensor 12 to the ECU 6, and the ECU 6 detects a road surface state based on the sensor signal and outputs a detection signal. In order to detect the operating state of the window wiper 13 of the vehicle 2, a connection signal is supplied from the wiper switch 14 to the ECU 6 during the operation.

The road surface sensor 12 is mounted on a lower surface of a front portion of the vehicle 2 in the vehicle 2. More specifically, as shown in FIG. 2, the road surface sensor 12 is mounted on the lower surface of the vehicle body 16 and immediately before the front wheel FW on one side. The road surface sensor 12 is configured as an optical sensor unit in which an optical element is built in a sensor casing 18. Specifically, the light projecting device 20 and the light receiving device 22 are built in the sensor casing 18. In the sensor casing 18, the light projector 20 and the light receiver 22 are arranged at appropriate intervals in the width direction of the vehicle body 16, and for example, in the vehicle width direction, the light projector 20 is located outside, and
The light receiver 22 is located inside.

The floodlight 20 emits detection light (for example, infrared light) toward the center in the width direction of a road surface area located immediately before the front wheel FW on the road surface RS.
The light receiver 22 receives the light reflected on the road surface area, that is, the reflected light. The incident angle θ _IN of the detection light with respect to the road surface RS and the reflection angle θ _OUT of the reflected light are values within a range sufficiently smaller than the so-called Brewster angle (eg, θ _IN
= Θ _OUT = about 12 °). Therefore, the distance between the light emitter 20 and the light receiver 22 is narrow when viewed in the vehicle width direction,
The sensor casing 18, that is, the road surface sensor 12 itself is downsized.

In this embodiment, the light projector 20 has a polarization filter 24, and the detection light emitted from the light projector 20 is polarized in one direction. For example, the detection light is polarized in one of a horizontal direction and a vertical direction with respect to the road surface RS. On the other hand, as shown in FIG. 3, the light receiver 22 also has a polarizing filter 26. When the polarizing filter 26 receives the reflected light condensed through the lens 27, the reflected light is transmitted to the road surface RS. , Respectively, into a horizontal polarization component Ph and a vertical polarization component Pv. The horizontal polarization component Ph and the vertical polarization component Pv are transmitted through the light reception processing circuit 28 to the EC.
It is supplied to U6.

In the ECU 6, the horizontal and vertical polarization components Ph and Pv of the reflected light are first processed in an averaging processing section 30, which takes a moving average of the horizontal and vertical polarization components Ph and Pv. These are output as horizontal and vertical polarization intensities Fph and Fpv. Here, the moving averaging process is performed based on the vehicle speed of the vehicle 2. Therefore, the averaging process section 30 is also supplied with the vehicle speed data V. This vehicle speed V
Is detected by, for example, a vehicle speed sensor 32 mounted on the vehicle 2. Note that a wheel speed sensor may be attached to each wheel of the vehicle 2 in place of the vehicle speed sensor 32, and the wheel speed detected by the wheel speed sensor may be converted into the vehicle speed V in the ECU 6.

[0015] In the averaging process section 30, the vehicle speed V is the average within a predetermined time period of the horizontal and vertical polarization component Ph, Pv taken when in a less than a predetermined vehicle speed V _1, contrast,
When the vehicle speed V exceeds the vehicle speed V ₁ it was an average of between predetermined running distance is taken. Thereafter, the horizontal and vertical polarization intensities Fph and Fpv of the reflected light are read into the identification section 36 after passing through the low-pass filter 34. In this identification section 36, the horizontal and vertical polarization intensities F
The data of ph and Fpv are referred to a reflection intensity characteristic map prepared in advance.

Referring now to FIG. 4, there is shown an intensity distribution region of horizontal and vertical polarization components of reflected light, that is, a reflection intensity characteristic, which is seen for each of various representative road surfaces. Note that these reflection intensity characteristics are obtained by performing a running test of a vehicle on each representative road surface. FIG. 4 shows the distribution of the reflection intensity characteristic of each representative road surface on various representative road surfaces based on differences in road surface material, surface shape, and the like. Here, as the representative road surface, asphalt and concrete dry roads are used. There are wet roads where the road surface is wet with rain, etc., snow roads where the road surface is covered with snow, snowy roads with dirt on the snow surface, and white lines painted on the road surface. .

From the reflection intensity characteristics shown in FIG. 4, the following can be understood with respect to various representative road surfaces. That is, in the case of a dry road made of asphalt and concrete, it is understood that the detection light is relatively weakly reflected on the road surface and is uniformly scattered. Therefore, the intensities of the horizontal polarization component and the vertical polarization component in the reflected light are in a proportional relationship, and the region of the intensity distribution extends linearly and has a relatively narrow width. Here, the reflection intensity levels of the concrete drying path and the asphalt drying path are different. this is,
In the case of a concrete drying path, the surface is relatively white and the detection light is easily reflected, whereas in the case of an asphalt drying path, the surface is relatively black, so that the absorption rate of the detection light is low in the case of a concrete drying path. It is due to being higher than that. The reflection intensity characteristics of the asphalt drying path and the concrete drying path partially overlap.

In the case of a wet road, the reflection intensity characteristics are the same regardless of whether the road surface is asphalt or concrete, and it can be seen that the intensity of the horizontal polarization component is greater than the intensity of the vertical polarization component. . This is because, in the case of a wet road, the vertical polarization component of the reflected light is mainly absorbed by the water film formed on the road surface, while the horizontal polarization component increases. For this reason, the reflection intensities of the horizontal and vertical polarization components on the wet road are not in a proportional relationship, and as is apparent from FIG. 4, the reflection intensity characteristics of the horizontal and vertical polarization components are partially different from the reflection intensity characteristics of the concrete dry road. In the overlapping state, they extend long along the horizontal axis representing the horizontal polarization component. In the case of a wet path, the intensity of the vertical polarization component varies depending on the depth of the water film, but the intensity level falls within a predetermined range as shown in FIG.

It can be seen that the level of reflection intensity is higher on snowy roads than on concrete dry roads. This is because the reflectance of detection light is high because the snow surface is very white, and the detection light is strongly irregularly reflected on the snow surface. Therefore, in the case of a snowy road, the reflection intensity characteristics of the horizontal and vertical polarization components linearly extend above the reflection intensity characteristic of the concrete dry road, and its width is larger than the width of the reflection intensity characteristic in the dry road. It is even bigger. Here, also in the case of the reflection intensity characteristic of the snowy road and the reflection intensity characteristic of the concrete dry road, a part thereof is overlapped.

In the case of a snowy road with dirt, the reflection intensity characteristics of the horizontal and vertical polarization components in the reflected light are significantly displaced toward the side of the reflection intensity characteristic on a concrete dry road as compared with the reflection intensity characteristic of a snowy road. I understand. This is probably because dirt on the snow surface absorbs a part of the detection light. Therefore, as apparent from FIG. 4, the reflection intensity characteristics of the snowy road with dirt partially overlap with the reflection intensity characteristics of the snowy road, the concrete dry road, and the wet road.

Furthermore, white lines for indicating lane divisions and pedestrian crossings are drawn on a general road surface, and the reflection intensity characteristics at such white line portions are substantially the same as the reflection intensity characteristics at snowy roads. Overlap. This is because the surface of the white line is sufficiently white like a snowy road. FIG. 4 described above
From the distribution of the reflection intensity characteristics, a reflection intensity characteristic map for the identification section 36 can be obtained. In FIG.
The horizontal axis and the vertical axis are horizontal polarization intensity Fph and vertical polarization intensity Fpv
An example of the reflection intensity characteristic map represented as “?” Is shown.

The map shown in FIG. 5 shows that when the horizontal and vertical polarization intensities Fph and Fpv of the reflected light are both in a substantially square region where the road surface is low, the road surface can be identified as a "dry road", and The horizontal and vertical polarization intensities Fph, F
When both pv's are in a high rectangular area, it indicates that the road surface can be identified as a "snow road". On the other hand, in a rectangular region where the horizontal polarization intensity Fph is higher than the vertical polarization intensity Fpv, the road surface can be identified as a "wet road".

The identification section 36 identifies which area on the map shown in FIG. 5 the point specified by the read horizontal and vertical polarization intensities Fph and Fpv is, and detects the identification result MF in the detection section 38. Output to Here, the identification result MF is the “dry path” described above,
This is an identification signal indicating either a “wet road” or a “snow road”.

In the detection section 38, a detection signal M of the road surface condition is generated based on the identification result MF in the identification section 36.
is formed, and the detection signal Mμ is supplied to the display device 4. In the display device 4, the received road surface state detection signal M
In accordance with the type of μ, specific character information such as “dry road”, “wet road”, and “snow road”, and a symbol that allows the driver to image the road surface state are displayed on the display surface. Further, the detection signal Mμ may be supplied to an audio output circuit (not particularly shown) so that, for example, the road surface condition is announced from a speaker.

As shown in FIG. 3, the detection signal Mμ of the road surface state formed by the detection section 38 described above.
Is also supplied to the detection failure state determination section 40. Here, in the signal forming process in the detection section 38, information on the horizontal and vertical polarization intensities Fph and Fpv of the reflected light is also included in the detection signal Mμ in addition to the road surface state information. Accordingly, in the determination section 40, it is possible to not only obtain the type of the road surface condition as the detection result from the received detection signal Mμ, but also specify the point on the map shown in FIG. 5 when the detection result is obtained. it can. Then, in the determination section 40, it is determined whether or not the detection accuracy of the road surface state is in a poor state based on such a detection signal Mμ.

Hereinafter, the determination processing in the determination section 40 will be described in detail. First, referring to FIG. 6, the distribution of the reflection intensity characteristics on a typical wet road and a snowy road is shown, and respective prominent examples are shown by hatched areas W and S in FIG. ing. FIG.
The road surface state identification regions based on the reflection intensity characteristic map shown in FIG. 6 are superimposed, and the boundary line is indicated by a broken line in FIG.

When the vehicle 2 is traveling on a typical wet road (for example, a submerged road), the intensity distribution of the horizontal and vertical polarization components of the reflected light obtained from the road surface sensor 12 is remarkably represented in the region W. In this case, the intensity of the horizontal polarization component is extremely large due to the strong specular reflection on the road surface flood film, and when this is compared with a reflection intensity characteristic map, the horizontal polarization intensity is the highest in an area that can be identified as a wet road. On a big level.

On the other hand, on a typical snowy road (for example, a snowy road), the reflection intensity distribution is prominently represented in the region S. In this case, since the surface of the snowy road is very white, the reflection intensity increases in proportion to both the horizontal polarization component and the vertical polarization component, and reaches the maximum intensity level both on the map and in the identification area as the snowy road. is there. The above-described reflection intensity characteristics are seen when the transmission and reception of the detection light by the road surface sensor 12 are performed well. However, when a defect occurs in the road surface sensor 12 and the transmission / reception state of the detection light becomes defective,
The above-mentioned remarkable reflection intensity characteristics cannot be obtained even in a flooded road and a snowy road. Specifically, when dirt such as dust accumulates on the lens surface of the road surface sensor 12 as the vehicle 2 travels, the transmittance of the reflected light decreases, and the reflection intensity obtained at this time is determined for both the horizontal and vertical polarization components. It tends to decrease uniformly.

In this case, as shown in FIG. 6, the intensity distributions of the horizontal and vertical polarization components of the reflected light in the flood channel and the snowy road under the same conditions shift from the regions W and S to the decreasing side. Displaced into areas W 'and S', respectively. This means that the reflection intensity characteristic is shifted to a decreasing side as a whole due to contamination of the lens surface, and as a result, on wet roads and snowy roads, the horizontal and vertical polarization intensity of the reflected light exceeds the boundary on the map. This means that it may be displaced to the identification area of the dry road. For example, even if the actual road surface condition is a wet road, its water film is relatively shallow, and even if it is a snowy road, its surface is dirty and not very white. The level is close to the boundary with the dry road. In these cases, if the intensity level of the reflected light reaching the light receiver 22 becomes low due to contamination of the lens surface, the identification section 36 may erroneously identify the road surface state as a dry road.

According to the observations by the inventors, if the decrease in the reflected light transmittance due to the dirt on the lens surface is within 30%, the distribution areas W ′ and S ′ after the displacement are respectively reflected by the reflection intensity characteristics. When compared with the map, as shown in FIG. 6, these areas W ′ and S ′ are both within the identifiable area of a wet road or a snowy road, so that contamination on the lens surface does not affect the detection result. Has been confirmed.

On the other hand, on the dry road, even if the reflection intensity shifts to the decreasing side due to dirt on the lens surface, the distribution area on the map is not displaced from the identification area of the dry road to another area. It can be said that there is no mistake in detecting the drying path. Here, in FIG. 6, a line representing the lower limit value Dmin of the horizontal and vertical polarization components of the reflected light obtained on the actual dry path (for example, asphalt path) is indicated by a broken arc in the dry path identification area in FIG. Have been. That is, according to observations by the inventors, it has been confirmed that the reflection intensity obtained on the asphalt road is always at a level larger than the lower limit value Dmin when the lens surface is clean.

FIG. 7 shows the axis scale of FIG. 6 in an enlarged manner, and particularly shows the vicinity of a line representing the lower limit value Dmin in FIG. 6 in detail. As shown in the figure, the reflection intensity distribution on the asphalt road is remarkably represented in a hatched area D. When the intensity level of the reflected light decreases due to the dirt on the lens surface described above, the normal distribution region D is displaced beyond the lower limit Dmin line to a region D ′ on the decreasing side. In this case, the degree of contamination on the lens surface is such that the detection is not erroneous on the wet road and the snowy road (reflected light transmittance is 70% or more).

On the other hand, if the degree of dirt on the lens surface is worse and there is dirt on a wet road or a snowy road that is erroneously detected as a dry road, the distribution area D becomes the area D ″. Large displacement up to. Further, the present inventors have found that even if there is no dirt on the lens surface due to accumulation of dust or the like, for example, when many water droplets adhere, the intensity of the vertical polarization component is significantly reduced as compared with the horizontal polarization component of the reflected light. I have confirmed. In this case, the normal distribution region D 'is displaced to a region D'd due to a remarkable decrease in the intensity of the vertical polarization component, and the reflection intensity is lower than the lower limit Dmin in both the horizontal and vertical components.

As described above, based on the displacement characteristics of the reflection intensity distribution for each representative road surface with respect to lens contamination, which the inventors have confirmed,
The following is understood with respect to the detection failure of the road surface condition.
That is, in the actual flooded road and the snow-covered road, if the lens surface is dirty up to a reflected light transmittance of 70%, the reflection intensity distribution is determined on the reflection intensity characteristic map as the wet road or snow road identification area. Does not move to the identification area of the dry road. In this case, the identification result in the identification section 36 is not affected, and therefore, there is no possibility that these road surface conditions are erroneously detected as a dry road. However, when the road is a wet road or a snowy road and the reflection intensity is at a low level, the distribution area may be displaced beyond the boundary of the identification area on the map, and may be erroneously detected as a dry road.

On the other hand, in the actual drying path, the intensity levels of the horizontal and vertical polarization components have a predetermined lower limit, and the reflection intensity distribution does not fall below this lower limit when the lens surface is free from dirt. On the other hand, when the lens surface has dirt, the reflection intensity distribution on the dry road is lower than the lower limit, but even when the same dirt condition is not detected erroneously on the wet road and the snowy road as described above. There is.

Summarizing the above, firstly, if the detection result is the "dry path" and the horizontal and vertical polarization intensities at that time are in the region lower than the above-mentioned lower limit value Dmin, the lens surface becomes dirty. Dust or water droplets) can be determined to be attached. In the first case, it is considered that even if the dirt is not erroneously detected on the wet road and the snowy road, the dirt on the lens surface can be known from the actual decrease in the reflection intensity.

Second, there is actually rain or precipitation,
For this reason, when the detection result is still "dry road" despite the fact that the window wiper 13 of the vehicle 2 is operated, it is considered that the intensity level of the reflected light is reduced because the lens surface is dirty. Can be In the first and second cases where the dirt on the lens surface is assumed as described above, the determination section 40 determines that the detection of the road surface state is in a poor state. Specifically, FIG. 8 shows a circuit configuration for executing the determination processing. When either of the first and second cases described above is satisfied, the final dirt determination signal Dt is ORed. The data is output via a circuit 48. The determination section 40 includes determination circuits 42 and 44 for specifying an area on the reflection intensity characteristic map from the supplied detection signal Mμ. As shown in FIG. The wiper operation detection signal Wp is input to the switch 40 when the wiper switch 8 is turned on. Hereinafter, the function of the determination section 40 will be described with reference to FIG.

First, in the first case described above, the region on the reflection intensity characteristic map specified from the detection signal Mμ is a region having an intensity level lower than the lower limit Dmin for both the horizontal polarization component and the vertical polarization component. The determination circuit 42 has a map that defines a dirt determination area that matches this area. When the horizontal and vertical polarization components included in the detection signal Mμ are in this dirt determination area, the determination circuit 42 outputs a first determination signal. Is output. The first determination signal is held by the timer circuit 46. When the timer circuit 46 confirms that the first determination signal has been output continuously for a certain period of time or more, the held first determination signal is immediately ORed. 48. The first determination signal is output from the OR circuit 48 as a stain determination signal Dt.

Next, in the second case described above, the timer circuit 50
In this case, when the wiper operation detection signal Wp is continuously input for a predetermined time or more, this detection signal is supplied to the AND circuit 52. On the other hand, the area on the reflection intensity characteristic map specified from the detection signal Mμ is a dry road identification area (non-wet road /
Non-snow road area). The determination circuit 44 has a map that defines an identification area that matches this area, and the detection signal M
When the horizontal and vertical polarization components included in μ are in the identification area, the identification circuit 44 outputs an identification signal. AN
The D circuit 52 outputs the second determination signal on condition that both the detection signal and the identification signal are input.
The timer circuit 46 supplies the second determination signal to the OR circuit 48 immediately after confirming that the output of the second determination signal has continued for a predetermined time or more. In this case, the second determination signal is output from the OR circuit 48 as a dirt determination signal Dt.

Thereafter, the dirt determination signal Dt output from the determination section 40 is supplied to, for example, the display device 4 as shown in FIG. 3, and the display device 4 displays a message such as lens surface dirt on the display surface. Then, the driver is informed that the detection of the road surface condition is in a defective state. As described above, according to the road surface condition determination device of the embodiment, the road surface is determined to be “dry road”, “wet road” or “wet road” from the map of FIG. 5 based on the reflection intensity characteristics of the horizontal and vertical polarization components of the road surface reflected light. The state of the “snow road” is detected, and the road surface state can be displayed on the display surface of the display device 4.

At this time, the detection result of the road surface condition is "dry road".
However, if it is determined based on the detection signal Mμ that the detection result is obtained within the dirt determination area of the determination section 40, the detection state is defective and the actual On a wet road and a snowy road, the driver can be notified that these may be erroneously detected as a "dry road". In this case, it is possible to cope not only with dirt such as dust adhering to the lens surface but also with adhering water droplets.

Further, the road surface state cannot be detected as "wet road" or "snow road" continuously for a certain period of time or more even though the driver operates the window wiper 13 due to actual rainfall or snowfall. In the situation, since the detection state is already bad, even if "dry road" is displayed on the display surface of the display device 4, it is possible to notify the driver in advance that the detection result is not reliable.

If a device for removing dirt on the lens surface is separately provided and the dirt determination signal Dt is supplied to these devices to operate the device, for example, a washer liquid is sprayed on the lens surface, It is also possible to activate a surface wiper. If the timer circuits 46 and 50 are used for the determination in the determination section 40 as in this embodiment, for example, even if the window wiper 13 is operated at the beginning of rain, the road surface will not be flooded for a while. In such a situation, even if the second determination signal is output from the AND circuit 52 of FIG. 8, the dirt determination signal Dt is not output until the output continues for a certain period of time or more. The inconvenience of being determined as a detection failure state each time can be eliminated.

In the above-described embodiment, the detection signal Mμ is supplied from the detection section 38 to the determination section 40 in the configuration of the ECU 6, but the horizontal and vertical polarization intensities Fph, The signal of Fpv may be supplied respectively.
In this case, the determination section 40 (determination means) determines the detection failure state based on the reflection intensity characteristics of the horizontal polarization component and the vertical polarization component of the reflected light.

The vehicle equipment used at the time of rainfall or snowfall may be combined with not only the window wiper 13 of the embodiment but also other equipment (for example, a retractable soft top or the like).

[0046]

As described above, according to the road condition determining apparatus of the first aspect, it is possible to reliably determine that the detection state is defective without using a special optical unit. Is simplified and downsized. Moreover, since the reflection intensity characteristic of the road surface reflected light is used, the detection failure state can be determined regardless of the type of the road surface.

According to the road surface condition judging device of the second aspect, since the actual weather condition is further taken into consideration, further reliability is ensured in the judgment of the detection failure state.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a system constituting a road surface condition determination device according to an embodiment.

FIG. 2 is a diagram showing an arrangement of a road surface sensor with respect to a front wheel.

FIG. 3 is a block diagram showing a configuration in an ECU of the system of FIG. 1;

FIG. 4 is a graph showing distribution of reflection characteristics on various representative road surfaces.

FIG. 5 is a graph showing a reflection intensity characteristic map created based on the graph of FIG. 4;

FIG. 6 is a graph for explaining an influence of a stain on a lens surface of a road sensor on a reflection intensity distribution.

FIG. 7 is a graph showing an enlarged axis scale of FIG. 6;

FIG. 8 is a circuit configuration diagram showing details of a determination section in FIG. 3;

[Explanation of symbols]

 Reference Signs List 4 display device 6 ECU 12 road surface sensor 13 window wiper 14 wiper switch 20 light emitter 22 light receiver

Claims (2)

[Claims] Detecting means for separating a reflected light from a road surface into a vertical polarization component and a horizontal polarization component, detecting a road surface state based on reflection intensity characteristics of both polarization components, and outputting a detection signal; A determination unit configured to determine a detection failure state of the detection unit based on the detection signal from the unit. 2. A vehicle according to claim 1, further comprising detecting means for detecting an operation state of vehicle equipment used at the time of rainfall or snowfall and outputting a detection signal, wherein said determination means further performs detection based on said detection signal from said detection means. The road surface state determination device according to claim 1, wherein the determination is performed.