JPH11248626A - Road surface freezing detection sensor - Google Patents

Abstract

(57) [Summary] [PROBLEMS] A road surface freezing detection sensor mounted on a vehicle and optically detecting whether or not the road surface is frozen, without being affected even if dirt adheres to the lens surface. To enable stable detection. SOLUTION: Light is projected by two LEDs 11, 12 for regular reflection and diffuse reflection via one light projection lens 13, and two LEDs for regular reflection and diffuse reflection are received via one light receiving lens 23. Light reception by the two PDs 21 and 22 is performed. Thereby, the light projecting lens 13 and the light receiving lens 23
If the surface of the lens 13 becomes dirty and the transmittance of the lenses 13 and 23 changes, the amount of light received by the two PDs 21 and 22 changes at the same ratio. Thus, it is possible to stably detect whether or not the road surface is frozen.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vehicle mounted on a vehicle,
The present invention relates to a road surface freezing detection sensor that optically detects whether or not a road surface is frozen, and particularly relates to a technology for detecting a road surface state without being affected even if dirt adheres to a lens surface. .

[0002]

2. Description of the Related Art Conventionally, there has been known a gloss detection sensor for detecting a glossiness of a detection object based on a ratio of a specular reflection component and a diffuse reflection component contained in the reflected light from the detection object (for example, Japanese Patent Application Laid-Open No. H11-163873). See Japanese Unexamined Patent Publication No. 62-276885. In addition, there is one in which such a gloss detection sensor is applied to a vehicle to detect whether or not the road surface is frozen by being mounted on a vehicle. FIG. 16 shows an example of a conventional road surface freezing detection sensor. The road surface freezing detection sensor 100 includes a light projecting unit 110 that irradiates the road surface 101 with light at an incident angle α, and a reflection angle α on the road surface 101.
Regular reflection light receiving section 120 for receiving the reflected light regularly reflected by
And a diffuse reflection light receiving unit 130 that receives light reflected at an angle other than the reflection angle α, and detects the gloss of the road surface 101 based on the amount of light received from the regular reflection light reception unit 120 and the diffuse reflection unit 130. Things.

The light projecting section 110 is composed of a light projecting lens 111 having a transmittance η1 and a light emitting element 112. The specular reflection light receiving section 120 and the diffuse reflection light receiving section 130 are respectively a regular reflection light receiving lens 121 and a regular reflection light receiving element 122 having a transmittance η2, and a diffuse reflection light receiving lens 131 having a transmittance η3.
And a light receiving element 132 for diffuse reflection. The light projecting unit 110 and the regular reflection light receiving unit 120 are arranged in a positional relationship such that an incident angle = reflection angle (α) with respect to the road surface 101, and the diffuse reflection light receiving unit 130 reflects the regular reflection component. It is arranged at a position where light does not easily enter.

Assuming that the light amount of the regular reflection component contained in the light reflected from the road surface 101 is Ps1 and the light amount of the diffuse reflection component is Pd1, the light intensity Ps2 of the regular reflection component by the regular reflection light receiving element 122 is equal to the regular reflection light receiving lens 121. , The result is (η2 × Ps1). Further, the light intensity Pd2 of the diffuse reflection component by the diffuse reflection light receiving element 132 is affected by the diffuse reflection light receiving lens 131, so that (η3 × P
d1). Here, since the relationship of gloss = (light intensity of specular reflection component) / (light intensity of diffuse reflection component) is established between gloss and light intensity of each reflection component, gloss = η2 · Ps
1 / η3 · Pd1, and therefore, it is possible to detect whether or not the road surface is frozen based on the gloss.

[0005]

However, FIG.
In the road surface freezing detection sensor 100 as shown in FIG.
Regular reflection light receiving lens 121 and diffuse reflection light receiving lens 13
When dirt adheres to the surface of the lens 121, these lenses 121, 1
Since the transmittances η2 and η3 of the respective 31 vary at different ratios, the gloss varies as a result, and a dry road surface is erroneously determined to be a frozen road surface, and conversely, a frozen road surface is a dry road surface. May be erroneously determined. This is a serious problem in the on-vehicle type road surface freezing detection sensor 100 used in a situation where dirt easily adheres.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and can stably detect whether or not the road surface is frozen even when dirt adheres to the lens surface. It is an object to provide a road surface freezing detection sensor mounted on a vehicle.

[0007]

In order to achieve the above object, the present invention relates to a road surface freezing detection sensor mounted on a vehicle and optically detecting whether or not the road surface on which the vehicle runs is frozen. The first different from the traveling direction of the vehicle
And a light projecting unit that projects light on the road surface of the second area, receives light reflected from the first area as a specular reflection component, and light reflected from the second area as a diffuse reflection component, and receives the respective areas. And a processing circuit for outputting, as an output signal, a calculation result of the light receiving signal for each area by the light receiving unit, and a light projecting unit for irradiating two areas. The light receiving section is constituted by two light emitting elements and one light projecting lens, and the light receiving section is constituted by two light receiving elements for receiving light from two areas and one light receiving lens. .

In this configuration, the light emitted from the two light projecting elements is projected via the light projecting lens toward the road surfaces of the first and second areas different from each other in the traveling direction of the vehicle. The reflected light of the specular reflection component from one area and the reflected light of the diffuse reflection component from the second area are arranged at positions where the reflected light of each reflection component can be received via the light receiving lens. The light is received by the two light receiving elements. The processing circuit performs a calculation such as a ratio or a difference on the light receiving signals from the two light receiving elements, and outputs the calculation result as an output signal. The gloss level of the road surface is detected based on the output signal from the processing circuit, and whether or not the road surface is frozen is detected. In this way, two light beams are transmitted through one light projecting lens.
Since light is emitted by two light emitting elements and light is received by two light receiving elements via one light receiving lens, dirt adheres to the surfaces of the light emitting lens and the light receiving lens. Even if the transmittance of the lens changes, the amount of light projected to the two areas and the amount of light received by the two light receiving elements change at the same ratio or difference, and no change appears in the calculation result output from the processing circuit. .

[0009]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is an optical system configuration diagram of a road surface freezing detection sensor according to the present embodiment. Road surface freezing detection sensor 1
Is mounted on a vehicle and determines whether or not the road surface is frozen by optically detecting the gloss of the road surface on which the vehicle runs, and is used for specular reflection and diffuse reflection on the road surface. A light projecting unit 10 that irradiates light toward two areas 2 (first area) and 3 (second area), and a light receiving unit that receives light reflected from these two areas 2 and 3 20. The light projecting unit 10 includes light projecting elements (hereinafter, referred to as LEDs) 11 and 12 for regular reflection and diffuse reflection for irradiating the areas 2 and 3 respectively, and one light projecting lens 13.
Further, the light receiving unit 20 includes light receiving elements (hereinafter, referred to as PDs) 21 and 22 for specular reflection and diffuse reflection for receiving the reflected light from the areas 2 and 3, respectively, and one light receiving element. And a lens 23.

The light projecting lens 13 and the light receiving lens 23 are arranged so that the road surface is viewed vertically in a direction (x-axis direction) perpendicular to the y-axis direction (vehicle traveling direction). LED11
And PD 21 are for detecting a specular reflection component (light that is specularly reflected on the road surface) included in the light reflected from the road surface, and the angle (α) at which the incident angle and the reflection angle are equal to the area 2 on the road surface. ). The LED 12 and the PD 22 are for detecting a diffuse reflection component included in light reflected from a road surface. LE
D12 is disposed behind the LED 11 in the traveling direction of the vehicle, and emits light toward the area 3 in front of the traveling direction of the area 2, and the PD 22 is located at a position where the area 3 is in the field of view. Placed in That is, the field of view of the diffuse reflection component is located slightly ahead of the field of view of the regular reflection component with respect to the traveling direction of the vehicle. The light emitted from the two LEDs 11 and 12 is projected toward the areas 2 and 3 via the light projecting lens 13, and the reflected light from the areas 2 and 3 is respectively reflected via the light receiving lens 23 into the PD 21 and the light receiving lens 23. 2
2 is received.

FIG. 2 shows a circuit configuration of the road surface freezing detection sensor 1. The processing system of the road surface freezing detection sensor 1 has two L
Light emission driver 31 for controlling light emission by EDs 11 and 12
And a processing circuit 32 for calculating the glossiness (Is / Id) of the road surface from the electrical signal Is of the regular reflection component obtained by the PD 21 and the electrical signal Id of the diffuse reflection component obtained by the PD 22. Is done. This gloss (Is /
If Id) is large, it is determined to be a frozen road surface, and if it is small, it is determined to be a dry road surface.

As described above, according to the present embodiment, the light projecting lens 13 and the light receiving lens 23 are respectively provided for the specular reflection component and the diffuse reflection component. Even if dirt adheres to the surface of the lens 23 and the transmittance of the lenses 13 and 23 changes, the amount of light projected onto the two areas 2 and 3 on the road surface and the two PDs 2
The light receiving signals Is and Id from 1 and 22 change at the same ratio. Therefore, the output signal (Is / Id) from the processing circuit 32 does not change depending on the degree of dirt on the lenses 13 and 23, and the lens 1 determines whether or not the road surface is frozen.
The detection can be performed stably without being affected by the stains 3 and 23.

(Second Embodiment) As in the embodiment shown in FIG. 1, the specular reflection component and the diffuse reflection component are detected from different areas 2 and 3, respectively. The following problems occur when crossing a white line painted on the road surface in a direction perpendicular to the traveling direction. For example, as shown in FIG. 3, when the vehicle 34 is traveling at a constant speed and a white line 35 painted in a direction perpendicular to the traveling direction is present, the signal waveform of the regular reflection component A time difference corresponding to the speed of the vehicle 34 occurs between Is and the signal waveform Id of the diffuse reflection component. Therefore, the signal (Is / Id) corresponding to the degree of gloss obtained by the processing of the processing circuit 32 increases in certain intervals, and is erroneously detected as if the road surface is glossy.

This problem can be solved if the regular reflection component and the diffuse reflection component can be detected from the same position. The reason that the specular reflection component area can detect the same area as the diffuse reflection component area is that the vehicle has a distance L between the two areas.
It is when you proceed. That is, if the signal waveform Id of the diffuse reflection component before traveling the distance L and the regular reflection component waveform Is after traveling the distance L are used, the area of the diffuse reflection component area and the area of the regular reflection component area are the same. Can be considered.

FIG. 4 shows a configuration diagram of a processing system of the road surface freezing detection sensor according to the second embodiment. The road surface freezing detection sensor 1 solves the above-mentioned problem, and the processing circuit 32 is provided with the speed v of the vehicle, and the traveling distance is calculated based on the speed v. PD21,22
Are converted into digital signals Ss and Sd by an analog-to-digital converter (hereinafter, referred to as an A / D converter) 36, and then processed by a processing circuit 32.
Is input to The processing circuit 32 outputs the signal values Sd and Ss,
Ratio Ss / Sd corresponding to glossiness depending on vehicle speed v
Is output. Since the processing circuit 32 corrects a time delay corresponding to the variable speed, the processing is easier if a microcomputer or the like is used.

A method of calculating the ratio (Ss / Sd) by the processing circuit 32 will be described with reference to the flowchart of FIG. First, the signal Sd from the PD 22 is detected for the diffuse reflection component (S1), and then the traveling distance is calculated based on the speed v of the vehicle (S2). (S3). When the regular reflection component detection area reaches the diffuse reflection component detection area, the signal Ss from P21
Is detected (S4), and the ratio Ss / Sd is calculated (S4).
5). The travel distance calculated in S2 is updated each time the vehicle moves by the distance L between the detection areas.

(Third Embodiment) As shown in FIG. 6, when the traveling direction of the vehicle 34 changes due to steering, the area of the road surface to be detected differs between the diffuse reflection component detection area 3 and the regular reflection component detection area 2. And false detection may occur. The embodiment described below is for solving such a problem.

FIG. 7 is a configuration diagram of an optical system of a road surface freezing detection sensor according to a third embodiment. The road surface freezing detection sensor 1 includes a regular reflection PD array (hereinafter, referred to as a PDA) 24 in which the light receiving unit 10 includes PDs 41, 42, 43, and a PD.
A PDA 25 for diffuse reflection composed of 51, 52, 53 is provided, and these PDA 24, 25 are arranged in a direction (x-axis direction) orthogonal to the traveling direction of the vehicle. The PDs 41, 42, and 43 use the detection areas S1, S2, and S3 as light receiving fields, respectively.
Numerals 2 and 53 designate the detection areas D1, D2 and D3 as light receiving fields, respectively.
2, S3 and the detection areas D1, D2, D3 are arranged side by side in the x-axis direction on the road surface. The light projecting unit 10 includes the regular reflection irradiation area 5 including the detection areas S1, S2, and S3.
5 and the irradiation area 56 for diffuse reflection including the detection areas D1, D2, and D3 are optically adjusted so as to uniformly irradiate them.

FIG. 8 shows a circuit configuration corresponding to the optical configuration of FIG. In the processing circuit 32, in addition to the speed v of the vehicle 34,
The steering angle θ of the vehicle 34 is given. The output values from the PDs 41, 42, 43, 51, 52, and 53 are digitized by the A / D converter 36, and then converted to digital signals Ss1, Ss2, Ss3,
The signals are input to the processing circuit 32 as Sd1, Sd2, and Sd3.

The operation according to the third embodiment will be described with reference to FIG. FIGS. 9A and 9B show the detection positions of the regular reflection detection area and the diffuse reflection detection area before and after the traveling direction changes, respectively. Steering the vehicle 34 to the right
Is changed, the road surface position detected by the diffuse reflection component detection area D2 can be captured by the regular reflection component detection area S1, and the PDs 52 and 41 corresponding to these D2 and S1 respectively. The glossiness is detected based on the light receiving signals Sd2 and Ss1 from the CPU. Thus, the displacement between the detection areas for the specular reflection component and the diffuse reflection component can be suppressed, so that erroneous detection during traveling on a curve can be avoided. If the traveling direction changes to the left, the road surface position detected by the diffuse reflection component detection area D2 can be captured by the regular reflection component detection area S3. Corresponding PD5
The glossiness is detected based on the light receiving signals Sd2 and Ss3 from the light emitting devices 2 and 43. Furthermore, when the vehicle 34 goes straight, the glossiness is detected based on the light receiving signals Sd2 and Ss2 from the PDs 52 and 42 corresponding to D2 and S2. When the vehicle 34 is backing, detection is performed based on light reception signals from the PD 42 corresponding to the regular reflection component detection area S2 and the PDs 51, 52, 53 corresponding to the diffuse reflection component detection areas D1, D2, D3. If it is performed, as described above, displacement of the detection area is suppressed, and highly accurate detection is possible.

Gloss (Ss / Sd) by processing circuit 32
Will be described with reference to the flowchart of FIG. First, a signal Sd2 from the PD 52 for the diffuse reflection component is detected (S11), and this signal Sd2 is assumed to be a signal Sd for the diffuse reflection component (S1).
2). Next, the travel distance is calculated based on the speed v of the vehicle 34 from the speed sensor 33 (S13), and the process waits until the regular reflection component detection area reaches the diffuse reflection component detection area at the time of detecting Sd (S14). . Further, the steering angle θ and the light receiving signals Ss1, Ss2, from the PDs 41, 42, 43
Ss3 is detected (S15, S16), and if θ is large in the positive direction (YES in S17), it is determined that the vehicle 34 is being steered to the right, and the signal S from the PD 41 is determined.
Let s1 be the signal Ss for the specular reflection component,
s / Sd is calculated (S18, S19). If θ is not large in the plus direction (NO in S17) and small in the minus direction (YES in S20), it is determined that the vehicle 34 is being steered to the left, and the signal Ss3 from the PD 43 is determined.
Is used to calculate Ss / Sd (S21, S19). Further, when no inclination is observed in θ (N in S20)
O), it is determined that the vehicle 34 is traveling straight, and Ss / Sd is calculated using the signal Ss2 from the PD 42 (S22,
S19).

As described above, according to the present embodiment, by using the PD arrays 24 and 25 for the light receiving section and inputting the steering angle, the specular reflection component and the diffuse reflection component can be obtained even when traveling on a curve. Since the component detection areas can be the same, it is possible to avoid occurrence of erroneous detection when traveling on a curve.

(Fourth Embodiment) FIG. 11 is a configuration diagram of a vehicle equipped with a road surface freezing detection sensor according to a fourth embodiment. The present embodiment includes a ground speed sensor 37 for the road surface 38, calculates the travel distance of the vehicle 34 based on the speed v detected by the ground speed sensor 37, and further calculates the diffuse reflection component area based on the travel distance. By making the detection areas coincide with the regular reflection component area, the occurrence of erroneous determination is suppressed. In general, the speed of a vehicle is detected based on the rotation speed of wheels, so that when the tire slips, a speed higher than the actual speed is detected, and the detection region of the diffuse reflection component and the specular reflection component is shifted. On the other hand, when the ground speed sensor 37 is used as in the present embodiment, the speed v and the traveling distance can be accurately detected even if the tire slips, so that it is possible to accurately detect whether or not the road surface is frozen. can do.

(Fifth Embodiment) FIG. 12 is a configuration diagram of a vehicle equipped with a road surface freezing detection sensor according to a fifth embodiment. In the present embodiment, in addition to the configuration of the second or fourth embodiment, the distance between the road surface freezing detection sensor 1 (for example, one shown in FIGS. 1 and 7) and the road surface 38 is measured. A distance measurement sensor 39 is provided, and the distance L0 detected by the distance measurement sensor 39 is provided to the road surface freezing detection sensor 1.

As shown in the second embodiment, an important parameter for matching the detection areas of the regular reflection component and the diffuse reflection component on the road surface is the distance L between the two detection areas. This distance L varies according to the load of the vehicle. As shown in FIG. 13, when the load amount is large, the distance L0 between the light projecting lens 13 and the road surface 38 is short, so that the distance L is short. Conversely, when the load amount is small, Since the distance L0 between the light projecting lens 13 and the road surface 38 increases, the distance L increases. In the present embodiment, the distance L0 between the light projecting lens 13 and the road surface 38 is detected by the distance measuring sensor 39, and the distance L is calculated based on the detected distance. Also,
The detection positions of the regular reflection component and the diffuse reflection component do not shift, and it is possible to detect road surface gloss with higher accuracy. In addition, as this distance measuring sensor, for example, an optical sensor device using a triangulation method is used.

(Sixth Embodiment) Normally, LEDs deteriorate with time, and there are individual differences in the manner of deterioration.
For this reason, as shown in FIG. 1 described above, in the case where the two LEDs 11 and 12 for regular reflection and diffuse reflection are provided, if the degree of deterioration of the two LEDs 11 and 12 is different, the detection accuracy is reduced. Therefore, in a sixth embodiment described below, one LED constitutes the light emitting portion of the sensor. FIG. 14A is an optical system configuration diagram of a light projecting unit of the road surface freezing detection sensor according to the sixth embodiment, and FIG. 14B is an enlarged view of a beam splitter constituting the light projecting unit. Floodlight unit 10
Is a single LED 60, a collimating lens 61 for coupling light emitted from the LED 60, and a light 70a for specular reflection of the light coupled by the collimating lens 61.
And a beam splitter 6 for dividing the light into diffused light 70b
And 2. In this embodiment, one LED 6
From 0, two light projections 70a and 70 for regular reflection and diffuse reflection
Since b can be obtained, the influence of the deterioration of the LED 60 is eliminated, and more accurate road surface detection can be performed.

(Seventh Embodiment) FIG. 15 is an optical system configuration diagram of a light projecting unit of a road surface freezing detection sensor according to a seventh embodiment. In the present embodiment, a mirror 63 is arranged beside the LED 60, and the light reflected by the mirror 63 is projected toward the road surface via the lens 64 as a light beam 70a for regular reflection. The light directly from the LED 60 to the lens 64 is projected toward the road surface as a diffuse reflection light projection 70b. Thus, similarly to the above-described sixth embodiment, it is possible to obtain light projection 70a, 70b for regular reflection and diffuse reflection by one LED 60, and furthermore,
Since light that is not coupled by the lens 64 can be used as a light source, the total amount of light increases.

The present invention is not limited to the above embodiment, but can be variously modified. In the above description, an example in which the ratio of the electrical signals from the two light receiving elements is processed as the output signal has been described. However, even if the difference between the two signals is used as the output signal, almost the same effect can be obtained although a slight difference in performance occurs. can get. Also, (specular reflection component) / (specular reflection component + diffuse reflection component),
(Diffuse reflection component) / (specular reflection component + diffuse reflection component),
Similar effects can be obtained by detecting whether or not the road surface is frozen based on a calculation result such as (specular reflection component−diffuse reflection component) / (specular reflection component + diffuse reflection component). . Furthermore, in the above-described embodiment, the state of the road surface is detected based on the reflected light from the two areas 2 and 3. However, light is projected to three or more areas, and The detection may be performed based on the reflected light.

[0029]

As described above, according to the road surface freezing detection sensor of the present invention, light is emitted by two light emitting elements via the same light emitting lens, and two light is received via the same light receiving lens. The elements receive the specular reflection component and the diffuse reflection component, so that even if the surface of the light projecting lens or the light receiving lens is stained and the transmittance of these lenses changes, the two light receiving elements are changed. The amount of light received by the elements changes at the same ratio, and the result of calculation such as the ratio or difference of the light receiving signals from these light receiving elements is not affected by lens contamination. Therefore, it is possible to accurately detect whether or not the road surface is frozen without being affected by dirt on the lens.

[Brief description of the drawings]

FIG. 1 is an optical system configuration diagram of a road surface freezing detection sensor according to a first embodiment of the present invention.

FIG. 2 is a block diagram of the road surface freezing detection sensor.

FIG. 3 is a diagram for explaining a problem that occurs when a vehicle equipped with a road surface freezing detection sensor crosses a white line.

FIG. 4 is a block diagram of a road surface freezing detection sensor according to a second embodiment.

FIG. 5 is a flowchart illustrating a method of calculating glossiness by a processing circuit.

FIGS. 6A and 6B are diagrams showing a positional relationship between a diffuse reflection component detection area and a regular reflection component detection area before and after the traveling direction of the vehicle changes, respectively.

FIG. 7 is an optical system configuration diagram of a road surface freezing detection sensor according to a third embodiment.

FIG. 8 is a block diagram of the road surface freezing detection sensor.

FIGS. 9A and 9B show the positional relationship between the diffuse reflection component detection area and the specular reflection component detection area before and after the traveling direction of the vehicle equipped with the road surface freezing detection sensor is changed. FIG.

FIG. 10 is a flowchart illustrating a method of calculating glossiness by a processing circuit.

FIG. 11 is a configuration diagram of a vehicle equipped with a road surface freezing detection sensor according to a fourth embodiment.

FIG. 12 is a configuration diagram of a vehicle equipped with a road surface freezing detection sensor according to a fifth embodiment.

FIG. 13 is a diagram for explaining a relationship between a load amount of a vehicle and a distance between detection areas.

FIG. 14A is an optical system configuration diagram of a light projecting unit of a road surface freezing detection sensor according to a sixth embodiment, and FIG. 14B is an enlarged view of a beam splitter constituting the light projecting unit.

FIG. 15 is an optical system configuration diagram of a light projecting unit constituting a road surface freezing detection sensor according to a seventh embodiment.

FIG. 16 is a configuration diagram of a conventional road surface freezing detection sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Road surface freezing detection sensor 2 Area (1st area) 3 Area (2nd area) 10 Light emitting part 11,12 Light emitting element 13 Light emitting lens 20 Light receiving part 21,22 Light receiving element 23 Light receiving lens 24,25 PDA (Light receiving element) 41, 42, 43, 51, 52, 53 PD (Light receiving element) 32 Processing circuit 34 Vehicle 38 Road surface

Claims (1)

[Claims] 1. A road surface freezing detection sensor mounted on a vehicle and optically detecting whether or not a road surface on which the vehicle runs is frozen, the first and second road surfaces being different in a traveling direction of the vehicle. A light projecting unit for projecting light onto a road surface of an area, receiving reflected light of a specular reflection component from the first area, and reflected light of a diffuse reflection component from the second area, A light receiving unit that outputs a light receiving signal; and a processing circuit that outputs a calculation result of the light receiving signal for each area by the light receiving unit as an output signal, wherein the light projecting unit irradiates the two areas. 2
The light-receiving unit is configured to include two light-receiving elements for receiving light from the two areas and one light-receiving lens. Road surface freezing detection sensor.