JP3470750B2 - Road surface condition determination device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road surface state determination device for determining the state of a road surface on which a vehicle is traveling by using an optical method, and in particular, it can be known that the determination accuracy is poor. The present invention relates to a road surface state determination device.

[0002]

Related Background Art For example, Japanese Patent Publication No. 3-30116 discloses a distance measuring device 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 including a light emitting device and a light receiving device housed in a case, and a light receiving unit for detecting dirt in the case. Specifically, when light is emitted from the light emitter of the measurement optical unit toward the object to be measured through the light transmission window formed in the case, scattered light from the cover provided in the light transmission window Is detected by the light receiving unit for dirt detection, and dirt and the like attached to the cover is detected based on the intensity of the scattered light.

Therefore, according to the above distance measuring device,
It can be considered that it can be known that the detection accuracy of the measurement optical unit is correspondingly reduced depending on the degree of the detected dirt.

[0004]

However, since the known distance measuring device uses the dirt detecting light receiving unit in addition to the normally used measuring optical unit, the light receiving signal is processed to judge dirt and the like. An additional determination circuit for doing so is also required. The present invention has been made based on the above circumstances, and its purpose is to:
It is an object of the present invention to provide a road surface state determination device capable of confirming that the detection accuracy is reduced only by the main optical unit without providing an additional optical unit.

[0005]

In order to achieve the above object, a road surface condition determining device according to a first aspect of the present invention uses a detecting device to detect a road surface condition based on reflection intensity characteristics of vertical and horizontal polarization components of light reflected from the road surface. And outputs a detection signal, based on this detection signal, the vertical and horizontal polarization components
Is in the region where the reflection intensity of is lower than the lower limit of the dry road.
Then, it is determined that the detection means is in the detection failure state.

According to the road surface condition determining apparatus of the first aspect, the road surface on which the vehicle is traveling is selected from, for example, a dry road, a wet road or a snow road, based on the reflection intensity characteristics of the vertically and horizontally polarized components of the reflected light. The state is detected. At this time, even if the detection result of the detection means is a dry road,
The reflection intensity of the direct and horizontal polarization components can be obtained in a normal dry path.
If the area is lower than the
It is considered that there is a problem such as stains on the surface.
Erare, it is determined that the detected state in the detection means is defective.

[0007] road surface state discrimination system 請 Motomeko 2, the detection means
Allows the reflected light from the road surface to be polarized vertically and horizontally.
Based on the reflection intensity characteristics of both polarization components.
While detecting the road surface condition and outputting the detection signal, the detection means detects the operating condition of the vehicle equipment used during rain or snow, and detects the detection failure condition based on this detection signal and the road surface condition detection signal. judge.

According to the road surface state detecting apparatus according to claim 2, anti
Based on the reflection intensity characteristics of vertically and horizontally polarized components of the incident light
The road surface on which the vehicle is traveling is, for example, a dry road, a wet road or
Is detected in which condition, such as a snowy road. This and
Area where the reflection intensity of vertically and horizontally polarized components is extremely low.
If the detection signal is output at
If it is determined that the condition is bad, and if the road surface condition at the time of rain or snow is not detected by the detection means despite the presence of rain or snow, it is determined that the detected condition is bad. To be done. More preferably, when the road surface condition is not detected as a wet road or a snow road by the detection means despite the fact that the window wiper is operated at the time of rain or snow, it is detected by the above-mentioned dirt on the light-transmitting and receiving lens surfaces. The state is determined to be bad.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a road surface condition determining device will be described below. Referring to FIG. 1, a vehicle 2 equipped with a road surface state determination device according to an embodiment is shown. Vehicle 2
In the passenger compartment of the vehicle, a display device 4 for displaying the road surface condition is arranged on an instrument panel.
Is supplied with a detection signal of a road surface state output from an electronic control unit (ECU) 6. Display device 4
On the display surface of, information about the road surface on which the vehicle 2 travels is displayed based on the detection signal. 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 the road surface state based on this sensor signal and outputs a detection signal. Further, in order to detect the operating state of the window wiper 13 of the vehicle 2, the ECU 6 is supplied with a connection signal from the wiper switch 14 during the operation.

The road surface sensor 12 is mounted on the lower surface of the front portion of the vehicle body of the vehicle 2. More specifically, as shown in FIG. 2, the road surface sensor 12 is attached to the lower surface of the vehicle body 16 immediately in front of 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, and specifically, the sensor casing 18 has a light projector 20 and a light receiver 22 built therein. In the sensor casing 18, the light emitter 20 and the light receiver 22 are arranged at an appropriate interval in the width direction of the vehicle body 16. For example, the light emitter 20 is located outside in the vehicle width direction, and
The light receiver 22 is located inside thereof.

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

In the case of this embodiment, the projector 20 has a polarization filter 24, and the detection light emitted from the projector 20 is polarized in one direction. For example, the detection light is polarized in one of the horizontal direction and the 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 polarization filter 26. When the polarization filter 26 receives the reflected light collected through the lens 27, the reflected light is reflected by the road surface RS. To the horizontal polarization component Ph and the vertical polarization component Pv. The horizontal polarization component Ph and the vertical polarization component Pv are transmitted to the EC through the light receiving processing circuit 28.
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, and therefore the vehicle speed data V is also supplied to the averaging process section 30. This vehicle speed V
Is detected by, for example, a vehicle speed sensor 32 mounted on the vehicle 2. Instead of the vehicle speed sensor 32, a wheel speed sensor may be attached to each wheel of the vehicle 2, and the wheel speed detected by this wheel speed sensor may be converted into the vehicle speed V in the ECU 6.

In the averaging processing section 30, when the vehicle speed V is equal to or lower than the predetermined vehicle speed V ₁ , the horizontal and vertical polarization components Ph and Pv are averaged within a predetermined time.
When the vehicle speed V exceeds the vehicle speed V ₁ , the average is taken over a predetermined traveling distance. After this, the horizontal and vertical polarization intensities Fph, 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 intensity F of the reflected light is
The data of ph and Fpv are referred to the reflection intensity characteristic map prepared in advance.

Here, referring to FIG. 4, there are shown the intensity distribution regions of the horizontal and vertical polarization components of the reflected light, that is, the reflection intensity characteristics, which are seen for various representative road surfaces. It should be noted that these reflection intensity characteristics are obtained by conducting a running test of the vehicle on each representative road surface. FIG. 4 shows the distribution of the reflection strength characteristics of each representative road surface on various representative road surfaces based on the difference in the material and surface shape of the road surface. Here, the representative road surface is a dry road of asphalt and concrete. There are wet roads where these roads are wet due to rain, snow roads covered with snow, dirty snow roads with dirt on the snow surface, and white lines painted on the road surface. .

From the reflection intensity characteristics of FIG. 4, the following can be understood with respect to various representative road surfaces. That is, in the case of a dry road of asphalt and concrete, it is understood that the reflection of the detection light on the road surface is relatively weak and is scattered uniformly. Therefore, the intensities of the horizontal polarization component and the vertical polarization component in the reflected light have a proportional relationship, and the region of their intensity distribution linearly extends, and the width thereof is relatively narrow. Here, the concrete dry road and the asphalt dry road have different reflection intensity levels. this is,
In the case of a concrete dry road, the surface is relatively white and it is easy to reflect the detection light, whereas in the case of an asphalt dry road, the surface is relatively black. This is due to the higher price. The reflection intensity characteristics on the asphalt dry road and the concrete dry road partially overlap.

In the case of a wet road, regardless of whether the road surface is asphalt or concrete, the reflection intensity characteristics are similar, 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 water film formed on the road surface mainly absorbs the vertical polarization component of the reflected light, while the horizontal polarization component increases. Therefore, the reflection intensities of the horizontal and vertical polarization components on the wet road are not in a proportional relationship, and as is clear from FIG. 4, the reflection intensity characteristics of the horizontal and vertical polarization components are partly different from those 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 the wet path, the intensity of the vertically polarized light component also changes 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 the reflection intensity of the snow road is higher than that of the concrete dry road. This is because the snow surface is very white, so that the reflectance of the detection light is high, and the detection light is strongly diffused on the snow surface. Therefore, in the case of a snow road, the reflection intensity characteristics of its horizontal and vertical polarization components extend linearly above the reflection intensity characteristics of a concrete dry road, and its width is compared to the width of the reflection intensity characteristics of a dry road. However, it has become large. 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 overlaps.

In the case of a dirty snow road, the reflection intensity characteristics of the horizontal and vertical polarization components in the reflected light should be largely displaced toward the reflection intensity characteristics of the concrete dry road as compared with the reflection intensity characteristics of the snow road. I understand. It is considered that this is because dirt on the snow surface absorbs part of the detection light. Therefore, as is clear from FIG. 4, the reflection intensity characteristics of the dirty snow road partially overlap with the reflection intensity characteristics of the snow road, the concrete dry road, and the wet road.

Further, white lines are drawn on the general road surface to indicate lane divisions and pedestrian crossings, and the reflection intensity characteristics at such white line portions are substantially the same as the reflection intensity characteristics on snowy roads. Overlap each other. This is because the surface of a white line is sufficiently white, like a snowy road. FIG. 4 described above
A reflection intensity characteristic map for the identification section 36 can be obtained from the distribution of the reflection intensity characteristics of the. In Figure 5,
The horizontal and vertical axes represent horizontal polarization intensity Fph and vertical polarization intensity Fpv.
An example of the reflection intensity characteristic map expressed as is shown.

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

In the identification section 36, it is identified 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 the identification result MF is detected in the detection section 38. Output to. Here, the identification result MF is the above-mentioned “dry path”,
It is an identification signal indicating either "wet road" or "snow road".

In the detection section 38, the road surface state detection signal M is detected based on the discrimination result MF in the discrimination section 36.
μ is formed, and the detection signal Mμ thereof is supplied to the display device 4. In the display device 4, the received road surface state detection signal M
Depending on the type of μ, specific character information such as “dry road”, “wet road”, “snow road”, etc., and a pattern that makes the driver imagine 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 the road surface condition is announced from, for example, a speaker.

As shown in FIG. 3, the detection signal Mμ of the road surface condition formed by the above-mentioned detection section 38.
Is also supplied to the detection failure state determination section 40. Here, in the signal formation processing in the detection section 38, the detection signal Mμ includes information on the horizontal and vertical polarization intensities Fph and Fpv of the reflected light at the same time in addition to the road surface state information. Therefore, the determination section 40 can not only obtain the type of road surface condition that is 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, the determination section 40 determines whether or not the road surface state detection accuracy is in a defective state based on the detection signal Mμ.

The determination processing in the determination section 40 will be described in detail below. First, referring to FIG. 6, there are shown distributions of reflection intensity characteristics on typical wet roads and snowy roads, and prominent examples of each are shown by hatched regions W and S in the same figure. ing. In addition, FIG.
Areas for identifying the road surface state based on the reflection intensity characteristic map of are overlapped and shown, and the boundary line is shown by a broken line in FIG.

When the vehicle 2 is traveling on a typical wet road (for example, a flooded road), the intensity distribution of the horizontal and vertical polarization components of the reflected light obtained from the road surface sensor 12 is remarkably expressed in the area W. In this case, the intensity of the horizontal polarization component is extremely large due to the strong specular reflection at the road surface flooding film, and by comparing this with the reflection intensity characteristic map, the most horizontal polarization intensity in the area that can be identified as a wet road is obtained. At a great level.

On the other hand, in a typical snow road (for example, a snow-covered snow road), the reflection intensity distribution is significantly represented in the area S. In this case, since the surface of the snowy road is very white, its reflection intensity is proportionally large for 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 characteristic is observed when the road surface sensor 12 is transmitting and receiving the detection light satisfactorily. However, if a problem 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 snow-covered road. Specifically, when dirt such as dust accumulates on the lens surface of the road surface sensor 12 as the vehicle 2 travels, the reflected light transmittance thereof decreases, and the reflection intensity obtained at this time has both horizontal and vertical polarization components. It tends to decrease uniformly.

In this case, as shown in FIG. 6, the intensity distribution of the horizontal and vertical polarization components of the reflected light in the flooded channel and the snow-covered channel under the same conditions shifts from the regions W and S to the decreasing side, It is displaced into the regions W'and S ', respectively. This means that due to dirt on the lens surface, the reflection intensity characteristic shifts to the overall decrease side, and as a result, in the wet road and the snow road, the horizontal and vertical polarization intensity of the reflected light exceeds the boundary line on the map. This means that there is a case where the area is displaced to the identification area of the dry road. For example, even if the actual road surface condition is a wet road, if the water film is relatively shallow, or if the surface is snowy and the surface is dirty and not very white, the reflection intensity distribution on the map is It is on the level 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 dirt on the lens surface, the identification section 36 may erroneously identify the road surface condition as a dry road.

According to observations made 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 displacement are respectively reflected intensity characteristics. As shown in FIG. 6, when compared with the map, both of these areas W ′ and S ′ fall within the distinguishable area of the wet road or the snowy road, so that the dirt on the lens surface does not affect the detection result. It has been confirmed.

On the other hand, in the dry road, the distribution area on the map is not displaced from the identification area of the dry road to another area even if the reflection intensity is shifted to the decrease side due to dirt on the lens surface. It can be said that there is no mistake in detecting the dry road. Here, in FIG. 6, a line indicating the lower limit value Dmin of the horizontal and vertical polarization components of the reflected light obtained on the actual dry road (for example, asphalt road) is shown by a dashed arc in the dry road identification area in the figure. Has been done. That is, the observation by the inventors has confirmed that the reflection intensity obtained on the asphalt road is always at a level higher than the lower limit value Dmin in a state where the lens surface is not dirty.

FIG. 7 is an enlarged view of the axis scale of FIG. 6, and particularly shows in detail the vicinity of the line representing the lower limit value Dmin in FIG. As shown in the figure, the reflection intensity distribution on the asphalt road is remarkably expressed in the hatched area D. When the intensity level of the reflected light is lowered due to the dirt on the lens surface as described above, the normal distribution area D is displaced beyond the line of the lower limit value Dmin to the area D'on the decrease side. In this case, the degree of dirt on the lens surface is such that the above-described wet road and snowy road are not erroneously detected (reflected light transmittance 70% or more).

On the other hand, when the degree of dirt on the lens surface is worse and there is dirt on the wet road and the snowy road which is erroneously detected as a dry road, the distribution area D becomes the area D ″. Is greatly displaced. The inventors have also found that the intensity of the vertically polarized component of the reflected light is significantly reduced compared to the horizontally polarized component of the reflected light when, for example, many water droplets are attached even if the lens surface is not contaminated due to accumulation of dust or the like. I'm confirming. In this case, the normal distribution area D ′ is displaced to the area D′ d due to a significant decrease in the intensity of the vertically polarized component, and the reflection intensity thereof is lower than the lower limit value Dmin for both the horizontal and vertical components.

From the displacement characteristics of the reflection intensity distribution for each representative road surface with respect to the lens dirt confirmed by the inventors as described above,
The following can be understood regarding the poor detection of the road surface condition.
That is, in the actual flooded and snow-covered roads, if the dirt on the lens surface is dirt with a reflected light transmittance of up to 70%, the reflection intensity distributions are the wet road or snow road identification areas on the reflection intensity characteristic map, respectively. To the identification area of the dry path. In this case, there is no influence on the identification result in the identification section 36, and therefore, there is no possibility that these road surface states are erroneously detected as a dry road. However, when the road surface is a wet road or a snow road and the reflection intensity is at a low level, the distribution region may be displaced beyond the boundary of the identification region on the map, and may be erroneously detected as a dry road.

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

Summarizing the above, firstly, when the detection result is a "dry path" and the horizontal and vertical polarization intensities at that time are in a region lower than the above-mentioned lower limit value Dmin, the lens surface becomes dirty ( It can be determined that a large amount of dust or water drops are attached. In the first case, it is considered that the dirt on the lens surface can be known from the actual reduction in the reflection intensity even if the dirt is not erroneously detected on the wet road and the snow road.

Secondly, there is actually rainfall or precipitation,
Therefore, if 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 lowered because the lens surface is dirty. To be In the first and second cases where the lens surface is contaminated as described above, the determination section 40 determines that the detection of the road surface state is in a defective state. Specifically, FIG. 8 shows a circuit configuration for executing the determination processing. When either one of the above-described first and second cases is established, the final stain determination signal Dt is ORed. The signal is output via the circuit 48. The judgment section 40 includes judgment circuits 42 and 44 for specifying the area on the reflection intensity characteristic map from the supplied detection signal Mμ, and as shown in FIG. A wiper actuation detection signal Wp is input to 40 when the wiper switch 8 is turned on. The function of the determination section 40 will be described below with reference to FIG.

First, in the above-mentioned first case, the area on the reflection intensity characteristic map specified from the detection signal Mμ is an area having an intensity level lower than the lower limit value Dmin for both the horizontal polarization component and the vertical polarization component. The determination circuit 42 has a map that defines a stain determination region that matches this region, and when the horizontal and vertical polarization components included in the detection signal Mμ are in this stain determination region, the determination circuit 42 outputs the first determination signal. Is output. The first determination signal is held by the timer circuit 46, and when the timer circuit 46 confirms that the first determination signal is continuously output for a certain time or longer, the first determination signal being held is immediately OR-circuited. Supply to 48. Then, the first determination signal is output from the OR circuit 48 as the stain determination signal Dt.

Next, in the above-mentioned second case, the timer circuit 50
Then, if the wiper operation detection signal Wp is continuously input for a certain period of 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 the dry road discrimination area (non-wet road,
It becomes a non-snowy area). The determination circuit 44 has a map defining an identification area that matches this area, and the detection signal M
When the horizontal and vertical polarization components included in μ are in this discrimination area, the discrimination circuit 44 outputs a discrimination 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 continues for a certain time or longer. In this case, the second determination signal is output from the OR circuit 48 as the stain determination signal Dt.

Thereafter, the dirt determination signal Dt output from the judging 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 its display surface. Then, the driver is informed that the detection of the road surface condition is defective. As described above, according to the road surface state determination device of the embodiment, the road surface is a “dry road”, a “wet road”, or a map based on the reflection intensity characteristics of the horizontal and vertical polarization components of the road surface reflected light, It is possible to detect which of the “snowy roads” the vehicle is in and display the road surface state on the display surface of the display device 4.

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

Further, although the driver is operating the window wiper 13 due to rain or snow, the road surface condition cannot be continuously detected as "wet road" or "snow road" for a certain period of time or longer. In the situation, since the detection state is already poor, 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, for example, a washer liquid is sprayed on the lens surface or the lens surface is removed. It is also possible to activate the wiper for the surface. If the timer circuits 46 and 50 are used for the determination in the determination section 40 as in this embodiment, the road surface will not be flooded for a while even if the window wiper 13 is operated at the beginning of rain. In such a situation, even if the second determination signal is output from the AND circuit 52 of FIG. 8, the contamination determination signal Dt is not output until the output continues for a certain period of time or more. It is possible to eliminate the annoyance of being determined to be in the detection failure state each time.

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 determination section 40 is directly supplied from the low-pass filter 34 to the horizontal and vertical polarization intensities Fph, The signals 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 during rain or snow may be not only the window wiper 13 of the embodiment but also other equipment (for example, a retractable soft top).

[0046]

As described above, according to the road surface condition determining device of the first aspect, it is possible to reliably determine that the detected condition is defective without using a special optical unit, and the device can be surely determined. Can be simplified and miniaturized. Moreover, by utilizing the reflection intensity characteristics of the road surface reflected light , vertical and horizontal
In the region where the reflection intensity of the polarized component is lower than the lower limit of the dry path
Since the detection failure state is determined at some time, the detection failure state can be determined regardless of the type of road surface.

[0047] According to a road surface state detecting apparatus according to claim 2, Special
Without using another optical unit
It is possible to reliably determine that
Downsizing and miniaturization. Moreover, the reflection intensity of the road surface reflected light
Since the characteristics are used and the actual weather conditions are taken into consideration, the detection failure state can be determined regardless of the type of road surface.
Can be, greater reliability determination detection fault condition is ensured.

[Brief description of drawings]

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

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

FIG. 3 is a block diagram showing a configuration inside the ECU in the system of FIG.

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

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

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

7 is an enlarged graph showing the axis scale of FIG.

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

[Explanation of symbols]

4 display device 6 ECU 12 Road surface sensor 13 window wiper 14 Wiper switch 20 Floodlight 22 Light receiver

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields investigated (Int.Cl. ⁷ , DB name) G01N 21/00-21/01 G01N 21/17-21/61 Practical file (PATOLIS) Patent file (PATOLIS)

Claims (2)

(57) [Claims] 1. A detection means for separating 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; Based on the detection signal from the means,
And the horizontal polarization component reflection intensity is lower than the lower limit of the dry path
A road surface state determination device comprising: a determination unit that determines that the detection unit is in a poorly detected state when in the area . 2. Reflected light from a road surface is a vertically polarized component and water.
Separated into flat polarization components, the reflection intensity characteristics of both polarization components
Based on the detected road condition and output a detection signal
A stage, a detecting means for detecting the operating state of the vehicle equipped outputs a detection signal to be used during rain or snow-out based on the detection signal from the detection signal and the detection means from said detecting means and the The detection failure state of the detection means
A road surface condition determination device comprising a determination means for determining.