JP2003050198A - Apparatus and method for discriminating road surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a road-surface discrimination sensor and a road-surface discrimination apparatus, that can be miniaturized by receiving both of a regular reflection constituent and a diffusion reflection constituent by one light-receiving means. SOLUTION: The road-surface discrimination sensor 1 and a reflector 2 are arranged, while sandwiching a road 4, and light is applied to a road surface from the road surface discrimination sensor 1. When the reflection surface from the road surface is to be received by a light receiving means in the road surface discrimination sensor 1, a diffusion reflected components that directly returns from the road surface to the light-receiving means, and a regularly reflected components that are reflected by the reflector 2 and are returned to the light-receiving means are detected by the road-surface discrimination sensor 1. The road-surface state is discriminated, by utilizing the change in the light-receiving state of the diffusion reflection components and the regularly reflected components, depending on the road surface state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road surface discriminating device for irradiating a road surface with light and discriminating a road surface state from the flight time of the reflected light, and a road surface discriminating sensor used in the device.

[0002]

2. Description of the Related Art Conventionally, as a device for determining the road surface condition,
For example, there is one disclosed in JP-A-9-269381. This device irradiates the road surface with infrared light from a floodlight installed on the road, receives the reflected light reflected from the road surface with a specular reflection light receiver and a diffuse reflection light receiver, and uses these regular / diffuse reflection light. Drying the condition of the road surface from the comparison of the output from the light receiver and the road surface temperature detected by the road temperature sensor,
Determine whether it is wet, frozen, or snowy. This device takes advantage of the fact that when the road surface is irradiated with light, the light reception levels of the regular reflection component and the diffuse reflection component from the road surface are different.

[0003]

However, in the above-mentioned conventional apparatus, since the specular reflection component and the diffuse reflection component of the reflected light reflected from the road surface reach different positions, the specular reflection light receiver and the diffuse reflection light receiver are different. It is necessary to separately install and at different positions, and there are inconveniences that the electrical wiring becomes complicated and the entire device becomes large. Further, since there is only one measurement point on the road, there is a problem that the road surface state determination result does not always reflect the road surface state of the entire road.

An object of the present invention is to provide a road surface discriminating sensor and a road surface discriminating apparatus which can downsize the device by allowing one light receiving means to receive both specular reflection components and diffuse reflection components. is there.

Another object of the present invention is to provide a road surface discriminating sensor and a road surface discriminating device capable of discriminating the road surface condition of the entire road by one light receiving means.

[0006]

The present invention is configured as follows to solve the above problems. (1) The irradiation means for scanning and irradiating the road surface with light, the light receiving means for receiving the reflected light from the road surface by the light emitted by the irradiating means, and the flight time of the reflected light received by the light receiving means. A road surface determining means for determining a road surface state based on the road surface; and a reflecting means installed to face the irradiation means on the opposite side of the road, and the road surface determining means is irradiated by the irradiation means. Flight time of the light reflected from the road surface by the reflecting means, reflected again by the road surface and received by the light receiving means, and flight of diffuse reflection component of the reflected light received by the light receiving means. It is characterized in that the road surface condition at a plurality of points is determined from the time.

In the road surface discriminating apparatus of the present invention, the road surface discriminating means discriminates the road surface state from the flight time of the specular reflection component and the flight time of the diffuse reflection component received by one light receiving means.
Regular reflection occurs when the road surface is a mirror surface state, and diffuse reflection occurs when the road surface is uneven. The regular reflection component received by the light receiving means, the light emitted by the irradiating means is regularly reflected on the road surface, and the light is reflected by the reflecting means arranged opposite to the irradiating means on the opposite side of the road, The light is the light that has been specularly reflected again on the road surface and reached the light receiving means. On the other hand, the diffuse reflection component is the light emitted from the irradiation means and reflected back on the road surface. Therefore, the flight time of the specular reflection component is longer than the flight time of the diffuse reflection component. Therefore, it is possible to determine from the flight time whether the flight time of the reflected light received by the light receiving means is due to the specular reflection component or the diffuse reflection component. If there is only the diffuse reflection component, it can be determined that the road surface is uneven. If both the regular reflection component and the diffuse reflection component can be detected, it can be determined that the road surface state is neither a mirror surface state nor an uneven state, for example, a flooded road surface state.

Further, in the present invention, the light emitted from the irradiation means is scanned along the road surface. Thereby, the road surface condition at a plurality of points on the road surface can be determined, and the road surface condition of the entire road can be accurately determined.

(2) Irradiating means for irradiating the road surface with light, light receiving means for receiving reflected light from the road surface due to the light emitted by the irradiating means, and flight time of the reflected light received by the light receiving means. A road surface discriminating means for discriminating a road surface state based on the road surface discriminating means, the road surface discriminating means discriminating the road surface state from the flight time of the specular reflection component and the flight time of the diffuse reflection component received by the light receiving means. To do.

The road surface discriminating sensor of the present invention is combined with the irradiating means in the sensor and the reflecting means which is arranged on the opposite side of the road, and is structurally integrated with the reflecting means. It is not necessary and can be manufactured separately from the reflecting means and can be installed later on the road on which the reflecting means has already been installed.

(3) In the road surface discrimination sensor according to the above (2), the road surface discrimination means has a reference distance from the road surface determined by the mounting position of the irradiation means, a flight time of the specular reflection component received by the light receiving means, and It is characterized in that the road surface condition is determined by comparing the distance calculated from the flight time of the diffuse reflection component.

Since the flight time of the specular reflection component and the flight time of the diffuse reflection component can be replaced by the dimension of the distance, the reference distance from the road surface determined by the mounting position of the irradiation means and the distance detected from the above flight time. By comparing and, the road surface condition can be determined.

(4) In the road surface discriminating sensor according to the above (2), the road surface discriminating means receives the amount of reflected light received by the light receiving means, the flight time of the specular reflection component received by the light receiving means, and diffuse reflection. It is characterized in that the road surface state is discriminated from the distance calculated from the flight time of the component.

When trying to determine the road surface condition in detail, it may be difficult to detect the flight time only. For example, in a dry state and a wet state of the road surface, the light received by both of them cannot be discriminated because most of the received light is occupied by diffuse reflection components. Therefore, in the present invention, the road surface condition is determined by taking into consideration the amount of reflected light received by the light receiving means. For example, in the above example, the amount of received light is greater on a dry road surface than on a wet road surface.

(5) The road surface discrimination sensor according to any one of the above (2) to (4), and a reflection means installed opposite to the road surface discrimination sensor on the opposite side of the road, The reflected light from the road surface due to the light emitted by the irradiation means,
It is characterized in that the light is reflected by the reflecting means, reflected again on the road surface, and received by the light receiving means.

According to the present invention, there is provided the above-mentioned road surface discrimination sensor (2) to (4), and a reflecting means arranged opposite to the road surface discrimination sensor on the opposite side of the road. The specular reflection component is light that is reflected by the reflecting means and is reflected again on the road surface and received by the light receiving means.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram for explaining the principle of the present invention.

FIG. 1 (A) shows the irradiation and reflection of light when the road surface is a diffuse reflection object (for example, dry asphalt), and FIG. 1 (B) shows the irradiation and reflection of light when the road surface is a mirror surface object. FIG. 1C shows the state of irradiation and reflection of light when the road surface is a flooded road surface.

In FIG. 1A, a road surface discrimination sensor 1
Is provided with an irradiation means for irradiating the road surface with light and a light receiving means for receiving the reflected light from the road surface due to the light emitted by the irradiation means. The irradiation means is composed of a laser light irradiation means, and is provided with a polygon mirror so that the road surface 3 can be scanned with light. The light scanning direction is the width direction of the road surface in this example.

The road surface discrimination sensor 1 is installed on one end side in the width direction of the road 4, and the reflector 2 is installed so as to face the road surface discrimination sensor 1 and the opposite side of the road across the road. There is. Reflection surface of reflector 2, that is, road surface discrimination sensor 1
The surface on the side is a reflecting surface formed so as to perform retroreflection. By regressive reflection, regular reflection light from the road surface,
It is possible to return to the light receiving means by following the same route as going. In addition, this enables one light receiving unit to receive both the specular reflection component and the diffuse reflection component.

In FIG. 1A, since the road surface 3 of the road 4 is dry asphalt (diffuse reflection object), the light P emitted from the road surface discrimination sensor 1 to the road surface 3 is diffusely reflected on the dry asphalt surface. Then, the light is received by the light receiving means of the road surface determination sensor 1. At this time, by measuring the flight time of the reflected light from the road surface discrimination sensor 1 to the irradiation point on the road surface, the distance from the road surface discrimination sensor 1 to the irradiation point on the road surface can be calculated. The calculated measurement distance is
It becomes L. When the road surface is dry asphalt, the light received by the light receiving means is mostly occupied by diffuse reflection components,
The regular reflection component is rarely included.

FIG. 1B shows the case where the road surface 3 is a mirror surface object. In this case, the light irradiated on the road surface 3 is
The light is specularly reflected on the road surface 3 and is regressively reflected by the reflector 2 installed so as to face the road surface determination sensor 1. The reflected light is on the road surface 3
Is again specularly reflected and is received by the light receiving means of the road surface determination sensor 1. When the road surface 3 is a mirror surface, the light is specularly reflected on the road surface 3 toward the reflector 2 and is reflected back there, and then specularly reflected on the road surface 3 to return to the light receiving means. The flight time is twice as long as the flight time shown in FIG. That is, the calculated measurement distance is 2L.
When the road surface is a mirror surface object, most of the light received by the light receiving means is occupied by the specular reflection component, and the diffuse reflection component is rarely included.

FIG. 1C shows a case where the road surface 3 is a flooded road surface. On the surface of the submerged road, a water film is formed on the surface, and the water film acts like a mirror. Therefore, the light applied to the submerged road surface is separated into light that is specularly reflected on the surface of the water film and light that is transmitted through the water film and diffusely reflected on the underwater film road surface below the water film. The light specularly reflected on the surface of the water film is specularly reflected by the reflector 2 and then specularly reflected again on the surface of the water film to return to the light receiving means. Also,
The light transmitted through the water film and diffusely reflected on the undersurface of the water film is diffusely reflected and received by the light receiving means. As a result, the light received by the light receiving means of the road surface discrimination sensor 1 becomes a composite of the regular reflection component and the diffuse reflection component, and its flight time is longer than the flight time shown in FIG. The flight time is shorter than the flight time shown in 1 (B). That is, the measurement distance is L <measurement distance <2L.

In this embodiment, as can be understood from FIG. 1, the road surface condition is determined by the flight time of the light emitted from the irradiation means, that is, the measured distance calculated from the flight time.

FIG. 2 is a view showing the installation state of the road surface discrimination sensor 1 and the reflector 2. The road surface discrimination sensor 1 is provided with a laser light irradiation means capable of scanning in the width direction of the road as an irradiation means, and an angle θ is set as a scanning range. This scanning range is set on the road 4 as a range corresponding to the range of the road surface 3 to be detected. Q is a laser light irradiation range corresponding to the above θ. As described above, by providing the laser light irradiation means capable of scanning in the width direction of the road, it is possible to determine the road surface condition at a plurality of points on the road, and it is possible to accurately determine the road surface condition of the entire road. .

In the present embodiment, the road surface discrimination sensor 1
In addition, a road surface temperature sensor 5 that detects the temperature of the road surface 3 is installed. The road surface temperature sensor 5 is used to determine the road surface state in combination with the determination result by the road surface determination sensor 1, and, for example, an infrared radiation thermometer or the like is used.

FIG. 3 is a block diagram of the road surface discrimination sensor 1. The LD (laser diode) drive circuit 11 is LD1
Laser light emitted by driving 0 is reflected by the reflecting surface of the polygon mirror 13 via the light projecting lens 12 and is applied to the road surface 3 as irradiation light. The reflected light from the road surface 3 is reflected by the reflecting surface of the polygon mirror 13, is received by the APD (avalanche photodiode) 15 via the light receiving lens 14, and is input to the light receiving circuit 16 as an electric signal.

The LD drive circuit 11 and the light receiving circuit 16 are
It is connected to the control unit 17. The control unit 17 further includes a motor drive circuit 18 and a scan start detection circuit 19
And are connected. The motor drive circuit 18 is connected to a motor 20 that rotationally drives the polygon mirror 13, and by driving this motor 20, the polygon mirror 1 is driven.
3 is driven at a predetermined rotation speed. Scan start detection circuit 1
Reference numeral 9 detects the reference position of the polygon mirror 13 and outputs a signal for controlling the scanning timing of the laser light to the control circuit 17.

The control circuit 17 is a time measuring circuit 17a for measuring the flight time from the irradiation of laser light to the reception of laser light.
A module control circuit 17b for controlling each module, a distance calculation circuit 17c for calculating a distance (a distance from the road surface discrimination sensor 1 to a road surface irradiated with laser light) from the measured flight time, and a road surface state It is provided with a road surface state discrimination circuit 17d for discriminating.

The operation of the road surface discrimination sensor 1 will be described in more detail below.

When the scan start detection circuit 19 detects a predetermined position of the polygon mirror 13, it outputs a scan start signal to the control circuit 17. When the control circuit 17 receives this scanning start signal, the LD drive circuit 11 drives the LD 10 to emit the laser beam to the polygon mirror 13.
And irradiate the road surface 3. The reflected light from the road surface 3 is reflected by the polygon mirror 13, received by the APD 15, and converted into an electric signal by the light receiving circuit 16. The light receiving circuit 16 specifically generates a stop signal and a received light amount signal. The stop signal is a signal for causing the time measurement circuit 17a in the control circuit 17 to receive a start signal from the LD drive circuit 11 to start time measurement and stop the time measurement. The light receiving circuit 16 forms a signal similar to a sine wave by differentiating the light receiving pulse input from the APD 15, or passes the sine wave signal by passing through a filter such as a BPF that passes a fundamental wave component. The stop signal is formed at the zero cross timing of this signal. The timing of this stop signal coincides with the timing of the peak position of the received light pulse.

When the time measuring circuit 17a measures the time from the start signal to the stop signal, the distance calculating circuit 17c calculates the distance based on this time. Since the above time is the round-trip time of the laser light, the actual distance L is calculated by ½ of the distance obtained from this round-trip time. Then, based on the calculated distance, the amount of light received by the light receiving circuit 16, and the road surface temperature information of the road surface temperature sensor 5, the road surface state determination circuit 17d determines the road surface state,
The result is output.

FIG. 4 is a diagram showing an outline of the operation of the light receiving circuit 16.

The received light pulse S input from the APD 15 is
Differentiated by an internal differentiation circuit. Normally, the received light pulse S has a shape as shown in the figure, and therefore, when differentiated, it has a waveform similar to a sine wave, and a zero cross point occurs. Since this zero cross point corresponds to the peak position of the light receiving pulse S, a stop signal is formed at this zero cross point. Further, the amount of received light is obtained by integrating the received light pulse S. Therefore, the light receiving circuit 16 is basically composed of an integrated circuit of the received light pulse, a differentiating circuit, and a stop signal forming circuit that forms a stop signal by the differentiating signal.

In the case of FIG. 1 (C), the received light pulse S corresponds to the reflected light from the surface of the water film and the reflected light from the lower surface of the water film below it. The reflected light from the surface of the water film is a component of the reflected light from the reflector 2 that is specularly reflected on the surface of the water film, and the light reflected from the road surface below the water film is diffused and reflected on the road surface. Therefore, the diffuse reflection component a and the regular reflection component b obtained by differentiating the received light pulses are as shown in FIG. Since the reflection components a and b after the received light pulse differentiation are close to each other in time, they are combined to be as shown in FIG. 4 (C). The zero-cross point of this combined signal is the stop signal generation timing. As is clear from FIGS. 4B and 4C, the generation timing of the stop signal of the combined signal c is the zero cross point of the diffuse reflection component a and the regular reflection component b.
It is located between the zero-cross points of. Therefore, the measurement time by the time measuring circuit is longer than the flight time when only the road surface as shown in FIG. 1 (A) and shorter than the flight time when the mirror surface as shown in FIG. 1 (B). That is, the measurement distance calculated by the distance calculation circuit is L <measurement distance <2L.

FIG. 5 is a diagram showing a storage state of the distance and the amount of received light in the road surface state determination circuit 17d.

The road surface condition determining circuit 17d includes a memory M1 for storing distance information and received light amount information, and stores distance information and received light amount information at each measurement point obtained for each scanning with a laser beam. To do. The distance information is distance measurement data calculated by the distance calculation circuit 17c, and the received light amount information is received light amount data input from the light receiving circuit 16.
The distance measurement data and the received light amount data are stored as L1 to Ln and P1 to Pn for the measurement points 1 to n for each scan, respectively. In the road surface state determination circuit 17d, the distance measurement data stored in the memory M1 is coordinate-converted into XY coordinates, and the conversion result is stored in the memory M2. The XY coordinates are coordinates when the height of the road surface is Y = 0 and the sensor light emitting surface of the road surface determination sensor 1 is X = 0, and the distance measurement data L1 to Ln stored in the memory M1 are represented by X. Data X1 to X
n and Y data Y1 to Yn are coordinate-converted to the memory M2
Remember. As for the Y component of the distance measurement data, since the height of the road surface is set to Y = 0, the height Y0 from the sensor projection emission surface determined by the mounting position of the road surface discrimination sensor 1 to the road surface is used as a reference distance in advance. Ask,
This reference distance Y0 is used for coordinate conversion. That is, the Y data Y1 to Yn after the coordinate conversion has a value obtained by subtracting Y0 from the Y component of the distance calculated by the distance calculation circuit.

With the above structure, the condition of the road surface is as shown in FIG.
In the case of a diffuse reflection object such as dry asphalt as shown in, X at measurement points 1 to n in one scan of laser light
The Y data is as shown by D1 in FIG.

The above-described data processing is performed in the road surface state determination circuit 17d of the control circuit 17.

FIG. 6 is a flow chart showing the data processing operation performed by the road surface state determination circuit 17d.

In step ST1, the distance measurement data stored in the memory M1 is coordinate-converted into XY data. Next, the variation of Y data for one scan is calculated (ST
2) Further, the received light amount data for one scan is sorted in descending order of received light amount (ST3). Next, N pieces are sequentially removed from the data with the largest received light amount (ST4), and N pieces are removed from the data with the smallest received light amount (ST5).
These steps ST4 and ST5 are for removing data with a large amount of received light and data with a small amount of received light, which are considered to be unsuitable for determining the road surface condition, and the number N to be removed is set to an appropriate value in advance. Is set. Next, the average value of the amount of received light in one scan of the laser light is calculated from the remaining amount of received light data (ST6).

7 to 10 show the relationship between the XY data stored in the memory M2 and the road surface condition.

FIG. 7 shows XY data when there is no snowfall or a vehicle on the road surface. When there is no snow or vehicles on the road,
The height data Y of the XY data is less than or equal to zero and never becomes higher than the road surface. In this case, the threshold value a (mm)
Is used, and this threshold value a is set in consideration of variations due to distance measurement.

FIG. 8 shows the light reflection state and XY data when the road surface is flooded.

When the road surface is flooded, as shown in FIG. 1 (C), a part of the light radiated toward the road surface is specularly reflected on the water film surface, reaches the reflector 2, and again reaches the water film surface. Then, the light is specularly reflected by and returns to the road surface discrimination sensor 1. Further, another part of the light passes through the surface of the water film, diffusely reflects on the road surface under the water film, and returns to the road surface determination sensor 1. The signals corresponding to the specular reflection component and the diffuse reflection component are combined as shown in FIG. 4C, and as a result, the measured Y data is the optical path length up to the reflector 2 and the water film under the diffuse reflection. It is a value between the optical path lengths to the road surface. Further, this value becomes larger as the time difference between the diffuse reflection component a and the regular reflection component b becomes longer in FIG. 4B, so that the closer the measurement point is to the sensor 1, the larger the Y data with respect to the reference distance Y0. When the measured Y data is larger than the reference distance Y0, the difference is represented by a negative value. As a result, when the road surface is submerged, the XY data is as shown by D3 in FIG. It should be noted that b (mm) is a threshold value set in consideration of variations due to distance measurement.

FIG. 9 shows the state and the XY data when the vehicle 10 is on the road 4. When the vehicle 10 is present on the road 4, the Y data for the laser light scanning after the specific m point becomes smaller than the reference distance Y0. D4
Indicates the XY data at this time. A threshold value c (mm) larger than the threshold value a (mm) is set. This threshold value c is for distinguishing the vehicle 10 from the snowfall, and the threshold value c is a value larger than the maximum snowfall amount on the road 4 (about 100 mm to 300 m).
m).

FIG. 10 shows the state and XY data when there is snow on the road 4. When there is snow 11 on the road 4, the Y data has a value that varies in the Y direction depending on the measurement point. Therefore, the XY data becomes as shown by D5 in FIG.

FIG. 11 shows a part of the road surface state determining operation in the road surface state determining circuit 17d, which is executed continuously from the data processing operation of FIG.

First, it is judged whether or not there are k or more pieces of data having a height a (mm) or more set as a threshold value in the Y data for one scanning of the laser light. k is
It is used as a threshold for considering the data below that as noise. In ST10, height a (mm)
When the above data does not exist k or more, the process proceeds to ST11. In this ST11, in the Y data for one scan,
It is determined whether or not there are k or more pieces of data having a height of −b (mm) or less. In this ST11, the determination explained in FIG. 8 is performed. That is, in the Y data, -b
When there are k or more data of (mm) or less, it is determined to be in a flooded state. Actually, the Y data is -b (mm) or less even in the state of ice burn instead of flooding. In the present embodiment, the state following this ice burn and flooding can be discriminated by the procedure that follows. In ST11, when there are no more than k pieces of Y data of -b (mm) or less, it is determined that the state is not flooded, and the process proceeds to the step of determining other road surface states.

In ST10, among Y data,
When there are k or more data of a (mm) or more, S
Proceed to T12. In ST12, it is determined whether or not there are k or more pieces of data having a height c (mm) or more in a certain X range. If it exists, it is determined in ST13 that there is a vehicle. If it does not exist, the possibility of snow 11
It will be determined in the subsequent steps.

FIG. 12 shows the operation following the discrimination operation of FIG. In FIG. 12, the received light amount data and the road surface temperature are further used to determine the road condition. The road surface temperature is information obtained by the road surface temperature sensor 5 in FIG.

ST20 is a step following ST12 of FIG. In this ST20, it is determined whether or not the average value of the amount of received light calculated in ST6 of FIG. 6 exceeds a predetermined value d. If the average value of the amount of received light exceeds d, S
In T21, it is determined whether the road surface temperature is lower than e. If the road surface temperature is lower than e, in ST22, it is determined that the vehicle is in a snowy state. When the average value of the amount of received light is not less than d or the road surface temperature is not less than e, the state is determined to be unknown in ST24 and ST23, respectively. In the snowy state, the average value of the amount of received light becomes large because the whole becomes whitish, and the road surface temperature also becomes low.
Therefore, in this case, the process proceeds to ST22, and it is determined that the snow cover state.

In ST25, it is determined whether or not the road surface temperature is lower than the predetermined value e, which is a step following ST11 in FIG. When the road surface temperature is lower than e, the routine proceeds to ST26, where it is determined that the vehicle is in the ice burn state, and when the road surface temperature is not lower than e, the routine proceeds to ST27 where it is determined that the vehicle is in the flooded state. In the flooded state and the ice burned state, the Y data show almost the same value, and thus, by using the information of the road surface temperature, the two are discriminated.

In ST28, which is a step executed after ST11 in FIG. 11, it is determined whether or not the average value of the amount of received light exceeds the predetermined value f. When the average value of the amount of received light exceeds the predetermined value f, the process proceeds to ST29, and it is determined whether the road surface temperature is less than the predetermined value e. When the road surface temperature is lower than e, it is determined in ST30 that the snow is in a compressed snow state, and otherwise, in ST31, the condition is unknown. Also, S
If the average value of the received light amount does not exceed the predetermined value f at T28, it is determined in ST32 whether the average value of the received light amount is less than the predetermined value g, and further in ST33, 1
It is determined whether the variation in Y data for scanning is less than or equal to a predetermined value h, and further in ST34, it is determined whether the road surface temperature is less than a predetermined value e.

In each of the condition judgments of ST28 to ST34 in the figure, the judgments of ST35 to ST38 are performed. That is, when it is determined in ST32 that the amount of received light is less than the predetermined value g, it is determined in ST35 that it is wet, and in ST33, when the variation of Y data for one scan is less than or equal to h, in ST36. When it is determined that the road surface temperature is less than the predetermined value e in ST34, it is determined in ST37 that it is a jam snow condition.
At other times, the state is determined to be unknown in ST38.

It should be noted that when jammed snow is present, snow on the sorbet remains on the road surface, so that the Y data may vary. On the contrary, when the road surface is dry, the Y data may not vary. Therefore, the threshold value h in ST33 is set to a value that can distinguish the dry road surface from the jammed snow. In addition, the amount of received light is considered to be: snow pressure state> jam snow state (or dry state)> wet state. Also,
It is considered that the road surface temperature is below a certain temperature when the snow is snowy or jammed. Average value of received light and threshold d
According to experiments, the relationship between f and g is preferably the following relationship.

D> f >> g Further, the predetermined value e to be compared with the road surface temperature is preferably set to about zero.

In the road surface condition determining operation shown in FIGS. 11 and 12, the road surface condition can be determined only by the determination in ST11 when the road surface is only in a dry state or in a flooded state. Further, to determine whether the road surface is in a dry state, a flooded state, a snowy state, or a state with a vehicle, it is sufficient to perform the determination operation including steps ST10 to ST12 in FIG.

As described above, by using the Y data in which the regular reflection component is taken into consideration on the road surface, the road surface state can be discriminated, and in addition to this, each information of the amount of received light and the road surface temperature is used. By doing so, it becomes possible to determine a more detailed road surface condition.

FIG. 13 shows the relationship between the road surface condition and parameters such as distance, amount of received light, distance distribution, and road surface temperature. In FIGS. 11 and 12, an algorithm using the relationship of the hatched areas in the relationship shown in FIG. 13 is used. Relationships other than the hatched area can also be used as an algorithm if necessary.

Next, a second embodiment of the present invention will be described.

In the second embodiment of the present invention, the control circuit 17 of FIG. 3 has a vehicle type pattern database. As shown in FIG. 9, when the vehicle 10 exists on the road 4, the Y data pattern from the measurement points m to n varies depending on the outer shape of the vehicle 10. 14
(A) and (B) show Y data patterns of different vehicle types. Therefore, by storing the Y data pattern corresponding to each vehicle type in the vehicle type pattern database in advance, the vehicle type of the vehicle 10 passing on the road 4 can be determined by referring to this vehicle type pattern database. .

Specifically, if it is determined in ST13 of FIG. 11 that there is a vehicle, the process proceeds to FIG. 15 and, in ST40, the vehicle type pattern database is referenced and a pattern that matches the obtained Y data pattern is extracted. It discriminates the vehicle type and outputs it to a display device or a host device connected by a line. The types of vehicles include motorcycles, bicycles, trucks, buses, etc. in addition to general vehicles, and may also include humans. Still another embodiment of the present invention will be described.

In this embodiment, by devising the shape of the polygon mirror 13, the laser light emitted from the road surface discrimination sensor 1 can be scanned not only in the width direction of the road but also in the traveling direction of the vehicle on the road. To FIG.
FIG. 16A shows a scanning state of the laser light when the vehicle traveling direction on the road 4 is viewed, and FIG. 16B shows a scanning state of the laser light when viewed from above the road 4. . The laser light scans by changing the scanning angle θ in the width direction of the road, and further scans by changing the scanning angle φ in the vehicle traveling direction of the road.

FIG. 17 shows the shape of a polygon mirror for performing scanning in the above θ and φ directions. As shown in FIG. 17, the polygon mirror 13 'has an upper surface and a lower surface in a regular hexagonal shape, and its side surface has a first mirror surface 13a (inclined inward at an angle m1 from a regular hexagonal ridge line d1 of the lower surface ( The mirror surface A) and the second mirror surface 1 arranged to be inclined inward at an angle m2 from the hexagonal ridge line d2 of the upper surface.
3b (mirror surface B) are alternately arranged. By rotating this polygon mirror 13 ',
On the mirror surface 13a, the laser light (incident beam) from the LD 10 is scanned in the angle θ direction, and in the next stage, at the position shifted in the angle φ direction on the mirror surface 13b (mirror surface B), the angle θ changes. Scanning is performed. Thereafter, each time the mirror surface changes, scanning in the θ direction is performed while changing the scanning position in the φ direction. In FIG. 17, since two types of surfaces, the mirror surface A and the mirror surface B, are used, scanning is performed alternately at two angles in the φ direction. However, by providing mirror surfaces with different tilt angles m, the φ direction The number of scans can be increased.

[0066]

According to the present invention, one light receiving means can receive both the specular reflection component and the diffuse reflection component, and the road surface condition can be discriminated from their flight times. The device can be downsized.
Further, since there is only one light receiving means, it is not necessary to consider the characteristic error of each light receiving means when using a plurality of light receiving means, and the measurement accuracy can be kept high. Moreover, the road surface condition of the entire road can be determined by one light receiving means.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the operation principle of a road surface discrimination device that is an embodiment of the present invention.

FIG. 2 is a diagram showing an installed state of the road surface discrimination device.

FIG. 3 is a configuration diagram of a road surface determination sensor

FIG. 4 is a diagram showing a light receiving pulse processing operation of a light receiving circuit.

FIG. 5 is a diagram showing a storage state of distance information and received light amount data.

FIG. 6 is a flowchart showing a data processing operation.

FIG. 7 is a diagram showing XY data on a dry road surface.

FIG. 8 is a diagram showing a relationship between laser beam reception data and XY data when a road surface is flooded.

FIG. 9 is a diagram showing a laser light receiving state and XY data when a vehicle is on the road surface.

FIG. 10 is a diagram showing a laser light receiving state and XY data when there is snow on the road surface.

FIG. 11 is a flowchart showing a part of road discrimination operation.

FIG. 12 is a flowchart showing another part of the road discriminating operation.

FIG. 13 is a diagram showing a relationship between information used for road discrimination and road conditions.

FIG. 14 is a diagram showing that the Y data pattern is different depending on the vehicle type in another embodiment of the present invention.

FIG. 15 is a flowchart showing an operation of discriminating a vehicle type from a Y data pattern.

FIG. 16 is a diagram showing a scanning direction of laser light in still another embodiment of the present invention.

FIG. 17 is a diagram showing the shape of a polygon mirror.

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Claims (6)

[Claims] 1. An irradiation unit for scanning light to irradiate the road surface, a light receiving unit for receiving reflected light from the road surface by the light emitted by the irradiation unit, and a flight of the reflected light received by the light receiving unit. A road surface determining means for determining a road surface state based on time; and a reflecting means installed opposite to the irradiation means on the opposite side of the road, the road surface determining means irradiating the road surface with the irradiation means. The light reflected from the road surface by the reflected light is reflected by the reflecting means, is reflected again on the road surface and is received by the light receiving means, and the diffuse reflection component of the reflected light received by the light receiving means. A road surface determination device, which determines road surface conditions at a plurality of points from the flight time of the vehicle. 2. An irradiation means for irradiating a road surface with light, a light receiving means for receiving reflected light from the road surface by the light emitted by the irradiating means, and a flight time of the reflected light received by the light receiving means. A road surface discriminating means for discriminating a road surface state according to the present invention, wherein the road surface discriminating means discriminates the road surface state from the flight time of the specular reflection component and the flight time of the diffuse reflection component received by the light receiving means. Road surface discrimination sensor. 3. The road surface determination means calculates a distance calculated from a reference distance from a road surface determined by a mounting position of the irradiation means, and a flight time of a specular reflection component and a flight time of a diffuse reflection component received by the light receiving means. 3. The road surface discrimination sensor according to claim 2, wherein the road surface condition is discriminated by comparing with. 4. The road surface discriminating means uses the amount of reflected light received by the light receiving means and the distance calculated from the flight time of the specular reflection component and the flight time of the diffuse reflection component received by the light receiving means. The road surface determination sensor according to claim 2, wherein the road surface condition is determined. 5. The road surface discrimination sensor according to claim 2, and a reflecting means installed opposite to the road surface discrimination sensor on the opposite side of the road surface from the road surface discrimination sensor. A road surface discriminating apparatus characterized in that light reflected from a road surface by the reflected light is reflected by the reflecting means, reflected again on the road surface and received by the light receiving means. 6. An irradiation means for irradiating a road surface with light, a light receiving means for receiving reflected light from the road surface due to the light emitted by the irradiation means, and a flight time of the reflected light received by the light receiving means. A road surface discriminating means for discriminating the road surface state by means of the road surface discriminating means, and the road surface discriminating means detects whether or not the light received by the light receiving means is regularly reflected by the light emitted from the irradiating means on the road surface. A road surface discriminating sensor characterized by discriminating and discriminating a road surface state based on the discrimination result.