JPH08193944A - Pavement state detector - Google Patents

Abstract

PURPOSE: To obtain a noncontact pavement state detector capable of detecting snowfall, frozen, wet or dry state of pavement. CONSTITUTION: The pavement state detector comprises a code pattern generator 20 for generating codes repetitively as an optical system and an infrared irradiation system, a modulator 21 performing the intensity modulation with a repetitive code being outputted out of the code pattern generator 20, a drive circuit 22, and an LED 1 being driven by the drive circuit 22 to emit infrared rays. The pavement state detector further comprises infrared photodiodes 8, 9 for receiving the horizontally and vertically polarized waves of a normal reflection light as an infrared light receiving system, infrared photodiodes 14, 15 for receiving the horizontally and vertically polarized waves of diffuse reflection light, an infrared photodiodes 17 receiving a reference irradiation light, demodulation circuits 23, 25, 26, 27, 28, a divider 24 for generating a plurality of threshold values, variable amplifiers 29, 30, 31, 32, comparison circuit blocks 33, 34, 35, 36, and a logic circuit 40 for determining the state of pavement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road surface condition detecting device, and in particular, for starting, stopping and adjusting the output of a snow-melting and anti-icing device for a road surface according to road surface conditions such as snow, freezing, wetting and drying. It is suitable for use as a detection device for detecting traffic conditions and as a road information detection device for traffic safety, and as a detection device for informing the driver of the condition of the road surface on which the vehicle is mounted to promote safe driving. Road condition detecting device.

[0002]

2. Description of the Related Art Conventionally, control such as starting, stopping, and output adjustment of a snow-melting and anti-icing device on a road surface is performed by controlling the outside air temperature,
This was done based on multiple observations such as black and white on the road surface and moisture on the road surface.

[0003]

As described above, conventionally, there has not been a sensor which can contactlessly and uniformly detect snow, freezing, wet and dry conditions on a road surface.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a road surface condition detecting device capable of detecting the snow accumulation, freezing, wetness and dryness of the road surface in a non-contact manner. To do.

[0005]

The road surface condition detecting device of the present invention is an infrared light generating means for generating infrared light intensity-modulated by a predetermined signal pattern, and is output from the infrared light generating means. The infrared light is polarized so that the horizontal polarization component and the vertical polarization component become equal to each other, and the infrared light is irradiated at a predetermined angle with respect to the road surface, and the irradiation light is directly received, and the irradiation light is Of the reflected light of, an optical system that receives the regular reflection light and the diffuse reflection light of a specific polarization plane at a predetermined angle with respect to the road surface,
A reference light detecting means for detecting the signal intensity of the irradiation light received by the optical system, and a reflected light detecting means for detecting the signal intensity of the regular reflection light and the irregular reflection light of the specific polarization plane received by the optical system, A comparison means for comparing the detection output of the reference light detection means and the detection output of the reflected light detection means, and outputting a signal according to the comparison result, and the comparison output of the comparison means are fetched, and each of the comparison result and the road surface. It is characterized in that it has a judging means for judging the road surface condition by collating with data stored in advance that is determined corresponding to the condition.

Further, the road surface condition detecting device of the present invention comprises an infrared light generating means for generating infrared light intensity-modulated by a predetermined signal pattern, and an infrared light output from the infrared light generating means. Polarized so as to form a plane of polarization of 0 °, irradiates the road surface at an angle of about 45 °, receives the irradiation light directly, and at the angle of about 45 ° to the road surface of the irradiation light. The reflected light reflected from the
An optical system that receives diffuse reflection light returning to the irradiation light source side and a regular reflection light in the traveling direction of the irradiation light, a reference light detection unit that detects the signal intensity of the irradiation light received by the optical system, and the optical system. Reflected light detecting means for detecting the signal intensities of the regular reflection light and the irregular reflection light of the received polarization planes 0 ° and 90 °, the detection output of the reference light detection means, and the four detection outputs detected by the reflection light detection means And a comparison means for outputting a signal according to the comparison result, and the comparison output of the comparison means is fetched, and the comparison result is collated with prestored data determined corresponding to each state of the road surface. However, it is characterized by having a determination means for determining the road surface condition.

In the road surface state detecting device of the present invention, the reference light detecting means is an integer multiple of 1 / n of the detected value of the light intensity of the irradiation light directly received by the optical system, as a reference. A plurality of thresholds are used as values, the plurality of thresholds are used as detection outputs, the reflected light detecting means has a variable amplifying means for amplifying the detection signal to a predetermined level, and the comparing means uses each of the comparison results as binary data. And the determination means,
By comparing the combination of binary data indicating each comparison result with the data stored in advance corresponding to each state of the road surface, the road surface state corresponding to the matched data is discriminated as the current road surface state. Characterize.

In the road surface state detecting device of the present invention, the infrared light generating means has a modulating means for intensity-modulating the irradiation infrared light having a polarization plane of 45 ° with a code pattern which is a repetitive code.
The reference light detection means and the reflected light detection means each include demodulation means for demodulating the reference light and each reflected light based on the code pattern.

[0009]

According to the road surface condition detecting device having the above-mentioned structure, since the snow surface is highly scattered, the vertical and horizontal polarization components due to the rotation of the polarization plane become strong in both regular reflection and irregular reflection, and in the wet surface the horizontal Since the appearance of the reflected light differs depending on the condition of the equal road surface where the regular reflection of the polarized component becomes stronger, by detecting the rotation of the polarization plane of the infrared light with 45 ° polarization plane by the regular reflection light and the irregular reflection light, Non-contact, snow on the road surface, freezing, wetting,
Each state of drying can be discriminated.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the construction of an optical system of an embodiment of a road surface state detecting device according to the present invention. In the figure, the infrared light from the infrared LED (1) is transmitted to the lower road surface (100) by the optical lens (2) via the polarizing plate (3) having a polarization plane of 45 ° and the infrared transmission filter (50). Optical axis toward 45 °, plane of polarization 4
As the irradiation light of 5 °, it is irradiated within the range of a solid angle of about 20 °.

The light spectrum radiant intensity of sunlight on the surface of the earth decreases for a while in the infrared region of the long wavelength region, and there is an absorption band due to water vapor in the transparent atmosphere and the wavelength of 1.4
It drastically decreases in μm. Therefore, the wavelength range of the radiated infrared light can be selected to a wavelength range in which the natural infrared light as the background does not exist, and is less likely to be affected by the infrared light as the disturbance.

On the other hand, the emission wavelength of the LED depends on the band gap of the semiconductor material, and the infrared LED made of the InGaAsP / InP semiconductor material can be selected to have the emission wavelength of 1.4 μm.

Further, the polarizing plate (3) having a polarization plane of 45 ° has a polarization angle of 45 °.
The infrared light of ° is set to cos45 ° and sin45 ° respectively, and the deviation of the polarization of the light source due to reflection inside the infrared light source is eliminated, and the intensity of the horizontal polarization component and the vertical polarization component of the irradiated infrared light is eliminated. Are equal.

The regular reflection infrared light reflected from the road surface (100) in the direction opposite to the irradiation infrared light source is detected by the irradiation infrared light source in a plane including the irradiation optical axis and perpendicular to the road surface (100). On the opposite side, at a position approximately 45 ° above the road surface 100 from the optical axis point on the road surface (100) of the illuminating light, and within the solid angle range of about 10 °, the road surface (1
00) through the optical lens (6), the infrared transmission filter (50), and the polarizing plate (4) with a polarization plane of 0 °, the regular reflection infrared light with a polarization plane of 0 ° is detected by the infrared phototransistor (8). Similarly, through the optical lens (7), the infrared transmission filter (50), and the polarizing plate (5) with the polarization plane of 90 °, which wants the road surface 100 within the solid angle range of about 10 °, the regular reflection infrared light with the polarization plane of 90 ° Is configured to be detected by the infrared photodiode (9).

The optical lenses (6) and (7) can be shared.

Diffuse reflected infrared light returning from the road surface (100) to the irradiation infrared light source side is detected by the irradiation infrared light source side on the road surface of the irradiation light in a plane including the irradiation optical axis and perpendicular to the road surface (100). (Ten
0) The optical lens (12), the infrared transmission filter (50), the polarization filter (50), which is about 45 ° above the road surface (100) from the optical axis point and wants the road surface (100) within a solid angle range of about 10 °. Polarizing plate with 0 ° wavefront
Optical lens (13), infrared light that wants to see the road surface (100) in the range of solid angle of about 10 ° by detecting diffusely reflected infrared light with polarization plane 0 ° through (10) with infrared photodiode (14) An infrared photodiode (15) detects diffusely reflected infrared light having a polarization plane of 90 ° through the transmission filter (50) and the polarized light (11) having a polarization plane of 90 °.

Also in this case, the optical lenses (12) and (13) can be shared.

On the other hand, the reference irradiation infrared light is detected from the irradiation infrared light source at a position which is located above the detection position of the diffuse reflection light and which does not cast a shadow on the solid angle on the detection side of the regular reflection light and the diffuse reflection light. Direct infrared light with a polarization plane of 45 ° through the optical lens (16) and infrared light transmission filter (50) to the infrared photodiode (1
It is configured to detect in 7).

In this embodiment, the infrared photodiode for detecting the reflected light of the radiated infrared light has an InG of 1.4 μm wavelength range.
aAsPIN photodiode or InP / InGaAs avalanche photodiode shall be used.

Next, FIG. 2 shows the electrical construction of an embodiment of the road surface state detecting device according to the present invention. In the figure, the road surface state detection device is a code pattern generator (20) that repeatedly generates a code because it needs to identify that the detection light is a reflection of irradiation light as its infrared light irradiation system, and a code pattern generator. (20) has a modulator (21) for intensity-modulating by a repetitive code, a drive circuit (22), and an infrared LED (1) driven by the drive circuit (22) to generate infrared light ing.

Infrared photodiodes (8) and (9) that receive regular reflected light as an infrared light receiving system that receives reflected light from the road surface (100) of infrared light and an infrared photo diode that receives diffused reflected light. Diodes (14) and (15), infrared photodiode (17) that receives the reference irradiation light, and demodulation circuits (23) and (2
5), (26), (27), (28), a divider (24) for generating a plurality of thresholds, a variable amplifier (29), (30), (31), (32), respectively, a plurality Comparing circuit block (3
3), (34), (35), (36) and comparison circuit block (33), (3
4), (35), and (36) based on each output, the logic determination circuit (40) for determining the road surface state.

The logical decision circuit (40) represents the magnitudes of the polarization components of the regular reflection light and diffuse reflection light of infrared rays by binary data, and these combinations correspond to each of snow, freezing, wet and dry conditions on the road surface. A built-in memory which is stored in advance, and the logic decision circuit (40) reads the 2
Combination of value data and each comparison circuit block (33), (34), (3
The road surface condition is determined by comparing the outputs of 5) and (36). This point will be described in detail later.

In the above configuration, the code pattern generator (2
Based on the signal of (0), the modulation circuit (21) obtains an electric amplitude modulation signal according to the code pattern, and the drive circuit (22) drives the infrared LED (1) to modulate the intensity according to the code pattern. Infrared light is applied to the irradiation light optical system. FIG. 3 shows an example of a code pattern of intensity-modulated infrared light.

Infrared light is intensity-modulated by a code pattern (62) which is a repetitive code and is applied to the road surface (100), and coincides with the code pattern (63) of the detected infrared light which is its reflected infrared light. It is possible to identify that the reflected light is infrared light emitted from the irradiation system of the road surface state detecting device according to the present embodiment. Irradiation light code pattern (62)
Sync signal (60) and the code (6
It consists of 1) and.

The infrared light emitted from the infrared LED (1) has a value sufficiently larger than the infrared radiation according to Planck's law of radiation, which depends on the temperature of the object to be illuminated.
Considering that it is superimposed on the level of reflected infrared light, the code pattern turns on (64) and turns off (65).
Infrared radiation according to Planck's law of radiation from the road surface (100) to be illuminated can be separated by setting the difference in the reflected light intensity.

The detection output of the infrared photodiode (17) for detecting the reference irradiation light is demodulated by the demodulation circuit (23) based on the electrical reference signal of the code pattern generator (20), and the road surface condition of this embodiment is obtained. Identifies the infrared light emitted by the detector and uses a divider (24) to determine the value corresponding to the albedo number of the black dry road surface by the infrared light emitted by the divider (24) as 1 / n of the detected intensity of the reference light.
Taking the reference value, 1 / n reference threshold, as well as a plurality of thresholds of integer multiples of 1 / n, for example, 10 / n, 100 / n, each comparison circuit block (33), (34), (35 ), And a reference signal serving as a reference for determining whether the logic is 0 or 1 is supplied to each comparator in (36).

The detection outputs of the infrared light photodiodes (8), (9), (14) and (15) for detecting the reflected infrared light are the electrical reference signals of the code pattern generator (20). Based on the demodulation circuit (25), (26), (27), (28) is recognized as reflected light of the infrared light emitted from the road surface state detection device of the present embodiment, the demodulation circuit (25 ), (26), (27), (28) output signals, respectively, through the variable amplifier circuit (29), (30), (31), (32), the comparison circuit block (33), (34) , (35), (36) are supplied to the respective comparators in the number corresponding to the threshold output number of the divider (24).

On the snow surface, which is a collection of transparent ice crystal particles, incident visible light and infrared light in the 1.4 μm band are repeatedly reflected and refracted on the surface of the ice crystal particles, and are perpendicular to the horizontal polarization component. Both the polarized components do not depend on the incident direction and show high reflectance for regular reflection and irregular reflection.

On a dry road surface, it exhibits a high absorptance with respect to infrared light in the 1.4 μm band, and has a normal reflection of both a horizontal polarization component of polarization plane 0 ° and a vertical polarization component of polarization plane 90 °, and weak reflection of irregular reflection. Indicates the rate.

On the frozen road surface, due to the presence of bubbles due to re-freezing of snow in addition to the ice surface, an intermediate reflection tendency between the snow surface and the dry road surface is exhibited.

Further, on a wet road surface, due to the presence of a minute water surface on the road surface, the regular reflection of the horizontal polarization component of the polarization plane 0 ° is dominant, and the normal reflection and irregular reflection of the vertical polarization component of the polarization plane 90 ° are horizontal. Both the polarization component and the vertical polarization component are very small.

The relationship between each road surface state and the level of the infrared light reflected from the road surface (100) is shown in the table below.

[0034]

[Table 1]

For example, as the threshold value of the divider (24), a value for discriminating the level of each reflected light from large, medium, small, and minute is:
If 1 / n of the detection intensity of the reference irradiation light and 10 × 1 / n and 100 × 1 / n based on this value are set as three points, 1 / n which represents a minute amount as an output of each comparison circuit block The following is 000,
Between 1 / n and 10 × 1 / n, which represent small, is 100, similarly 10 × 1 / n and 1
Four output patterns are obtained: 110 between 00 × 1 / n and 111 above 100 × 1 / n.

On the snowy road surface, the polarization planes 0 ° and 90 ° are strong in both regular reflection and irregular reflection, and the polarization plane 0 of the polarizing plate (4) for the regular reflection light is 0.
The output is 111 in the comparison circuit block (33) which is the detection system of the angle .degree., And the output is 111 in the comparison circuit block (34) which is the detection system of the polarization plane 90.degree. Of the polarizing plate (5).

The output of the comparison circuit block (35), which is a detection system for the polarization plane 0 ° of the polarizing plate (10), is 11 even for diffusely reflected light.
1. In the comparison circuit block (36) which is a detection system of the polarization plane 90 ° of the polarizing plate (11), the output is 111.

When all the outputs of the respective comparison circuit blocks are 111 for the planes of polarization 0 ° and 90 ° of the regular reflection and the irregular reflection, the logical judgment circuit (40) judges that the road surface is a snow surface.

On a dry road surface, the normal reflection and the irregular reflection of the polarization planes 0 ° and 90 ° are weak, and the output is 100 and the polarization plane 90 in the comparison circuit block (33) which is the detection system of the polarization plane 0 ° of the regular reflection light. The output of the comparator circuit block (34), which is a detection system for .degree., Is 100.

The output is 100 in the comparison circuit block (35) which is the detection system of the polarization plane 0 ° even with the diffused reflected light, and the output is 1 in the comparison circuit block (36) which is the detection system of the polarization plane 90 °.
Get 00.

When all of the polarization planes 0 ° and 90 ° of the regular reflection and the irregular reflection are 100, the logical determination circuit (40) determines that the road surface is dry.

On a frozen road surface, the output of the comparison circuit block (33), which is a detection system for the normal plane of polarization of 0 ° and the normal plane of polarization of 0 °, is 110-111 and the plane of polarization of 90 °. In the comparison circuit block (34) which is the detection system of, the output obtains 110.

The output of the comparison circuit block (35), which is a detection system for the plane of polarization 0 ° even for diffusely reflected light, is 100 to 110, and the output is 100, for the comparison circuit block (36), which is the detection system of the plane of polarization 90 °. Get ~ 110.

The logic determination circuit (40) determines that the road surface is frozen by the combination in which the detection output of each comparison circuit block in the polarization plane 0 ° of the regular reflection and the irregular reflection is dominant.

On a wet road surface, the normal reflection of the polarization plane 0 ° is dominant, and the output of the comparison circuit block (33) which is the detection system of the polarization plane 0 ° of the regular reflection light is 111 and the detection system of the polarization plane 90 °. The output of the comparator circuit block (34) is 100.

The output of the comparison circuit block (35), which is a detection system of the plane of polarization 0 ° even with diffusely reflected light, is 000, and the output is 0, in the comparison circuit block (36), which is the system of detection of the polarization plane 90 °.
Get 00.

The logical judgment circuit (4
It is judged to be a wet road surface in 0).

As described above, the infrared light in the specific wavelength range is irradiated onto the road surface with the polarization plane of 45 °, and the regular reflection from the road surface is performed.
The condition of the road surface can be determined without contact from the combination of the detected light intensities of the 0 ° and 90 ° polarization planes of each diffuse reflection.

[0049]

As described above, according to the present invention, infrared light generating means for generating infrared light intensity-modulated by a predetermined signal pattern, and the infrared light generating means outputs the infrared light. The infrared light is polarized so as to have a plane of polarization in which the horizontal and vertical polarization components are equal, and the infrared light is irradiated at a predetermined angle with respect to the road surface, and the irradiation light is directly received, and the reflected light of the irradiation light Of these, an optical system that receives the regular reflection light and the diffuse reflection light of a specific polarization plane at a predetermined angle with respect to the road surface, a reference light detection unit that detects the signal intensity of the irradiation light received by the optical system, and the optical system. The reflected light detection means for detecting the signal intensity of the regular reflected light and the diffused reflected light of the specific polarization plane received by, the detection output of the reference light detection means and the detection output of the reflected light detection means are compared, and the comparison result Comparing means for outputting a signal according to The comparison output of the comparison means is taken in, and the comparison result is collated with the data stored in advance corresponding to each state of the road surface, and the determination means for determining the road surface state is provided. Snowfall, freezing,
Wet and dry conditions can be detected without contact.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an optical system of a road surface state detecting device according to the present invention.

FIG. 2 is a block diagram showing an electrical configuration of a road surface state detecting device according to the present invention.

FIG. 3 is a waveform diagram showing an example of a code pattern of intensity-modulated infrared light in the road surface state detecting device according to the present invention, and an irradiation light code pattern and a detection light code pattern.

[Explanation of symbols]

 1 infrared LED 2 optical lens 3 polarization plane 45 ° polarization plate 4 polarization plane 0 ° polarization plate 5 polarization plane 90 ° polarization plate 6 optical lens 7 optical lens 8 infrared photodiode 9 infrared photodiode 10 polarization plane 0 ° polarization plate 11 polarization Wavefront 90 ° polarizing plate 12 Optical lens 13 Optical lens 14 Infrared photodiode 15 Infrared photodiode 16 Optical lens 17 Infrared photodiode 20 Code pattern generator 21 Modulation circuit 22 Drive circuit 23 Demodulation circuit 24 Divider 25 Demodulation circuit 26 Demodulation circuit 27 Demodulation Circuit 28 Demodulation circuit 29 Variable amplification circuit 30 Variable amplification circuit 31 Variable amplification circuit 32 Variable amplification circuit 33 Comparison circuit block 34 Comparison circuit block 35 Comparison circuit block 36 Comparison circuit block 40 Logic judgment circuit 42 Code pattern 43 Detection light Off portion of the on portion 45 code patterns of Dopatan 44 code pattern 50 infrared light transmitting filter

Claims (4)

[Claims] 1. An infrared light generating means for generating infrared light intensity-modulated by a predetermined signal pattern, and infrared light output from the infrared light generating means have equal horizontal and vertical polarization components. Polarized so that it becomes a plane of polarization, and irradiate at a predetermined angle to the road surface, the irradiation light directly,
An optical system that receives and receives the regular reflection light and the diffuse reflection light of a specific polarization plane of the reflected light of the irradiation light at a predetermined angle with respect to the road surface, and the signal intensity of the irradiation light received by the optical system. Reference light detecting means for detecting, reflected light detecting means for detecting signal intensity of regular reflected light and diffused reflected light of a specific polarization plane received by the optical system, detection output of the reference light detecting means and reflected light detection A comparison means for comparing the detection output of the means and outputting a signal according to the comparison result, and the comparison output of the comparison means are fetched and determined and stored in advance corresponding to the comparison result and each state of the road surface. A road surface state detection device, comprising: a determination unit that compares the data with the data to determine the road surface state. 2. Infrared light generating means for generating infrared light intensity-modulated by a predetermined signal pattern, and infrared light output from the infrared light generating means to have a polarization plane of 45 °. The polarized light is emitted at an angle of about 45 ° to the road surface, and the emitted light is directly received, and the reflected light reflected from the road surface at an angle of about 45 ° with respect to the road surface of the emitted light is emitted. An optical system that receives diffuse reflection light returning to the irradiation light source side and regular reflection light in the traveling direction of the irradiation light at polarization planes of 0 ° and 90 °, and detects the signal intensity of the irradiation light received by the optical system. A light detecting means; a reflected light detecting means for detecting the signal intensities of the regular reflected light and the diffused reflected light of the polarization planes 0 ° and 90 ° received by the optical system; the detection output of the reference light detecting means and the reflected light detection Compare the four detection outputs detected by the means, and compare A comparison means for outputting a signal according to the result and a comparison output of the comparison means are fetched, and the comparison result is compared with previously stored data determined corresponding to each state of the road surface to determine the road surface state. A road surface condition detecting device. 3. The reference light detecting means sets a plurality of threshold values, which are integer multiples of 1 / n of the detected value of the light intensity of the irradiation light received directly by the optical system, as a reference. The plurality of threshold values are used as detection outputs, the reflected light detection means has a variable amplification means for amplifying a signal to a predetermined level, the comparison means outputs each comparison result as binary data, and the determination means. Compares the combination of binary data indicating each comparison result with data stored in advance corresponding to each state of the road surface, and determines the road surface state corresponding to the matched data as the current road surface state. The road surface state detecting device according to claim 1, wherein 4. The infrared light generation means has a modulation means for intensity-modulating the irradiation infrared light having a polarization plane of 45 ° with a code pattern which is a repetitive code, and the reference light detection means and the reflected light detection means And a demodulation means for demodulating the reference light and each reflected light on the basis of the code pattern.
The road surface state detection device according to any one of 1.