JP3231257B2 - Method and apparatus for measuring road surface condition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring a road surface condition for confirming a road surface condition of a road, particularly a highway.

[0002]

2. Description of the Related Art Confirmation of road surface conditions, particularly of expressways, is an important matter for ensuring traffic safety. In particular, it is important to constantly monitor the state of road surface changes due to the increase in fog and humidity, as well as the occurrence of icing and the like in winter and the wetness of the road surface due to rain, and to immediately alert the driver when dangerous.

[0003] A conventional road surface condition measuring device irradiates a light wave from a general light wave type light projecting portion toward a road surface of a road, receives reflected light reflected on the road surface by a light receiving portion, and receives the reflected light. Was analyzed to determine the road surface condition.

[0004]

However, the above-mentioned conventional road surface condition measuring apparatus cannot be expected to efficiently determine, for example, the state of the road surface, that is, whether the road surface is wet, dry, or frozen. As a solution to the above-mentioned problem, the present applicant has already conceived a technique disclosed in Japanese Unexamined Patent Publication No.
In this publication, a light emitter and a light receiver are provided on both sides of a road, respectively, and a P / S ratio calculated based on received P-wave values and S-wave values is set in advance. The determined P / S setting ratio is compared and determined to grasp the road surface condition of the road.

Accordingly, when the light emitting section and the light receiving section are provided on both sides of the road, and the processing section is provided on one side of the road on which the light receiving section is provided, the light emitting section is provided. A power cable for connecting the power supply to the processing unit must be provided across the road, and it is very difficult to synchronize the control signals.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and an apparatus for measuring a road surface condition in which a power cable can be easily attached and control signals can be easily synchronized so that a more accurate road surface condition can be measured more easily than before. Is to provide.

[0007]

According to a first aspect of the present invention, there is provided a method for measuring a road surface condition, comprising the steps of: The laser beam is projected onto an appropriate number of reflection mirrors provided on the other side of the road, and the laser beam reflected by the reflection mirror is irradiated on the road surface of the road, and the scattered light or the reflected light is irradiated on the road surface. An appropriate number of light receiving units provided on one side of the road independently receive two orthogonally polarized light components, S-waves and P-waves, and calculate the actual P / S ratio of the received S-waves and P-waves. The P / S ratio is compared with a preset P / S ratio set value, and the wet, dry, and frozen state of the road surface is measured.

According to a second aspect of the present invention, there is provided a road surface condition measuring device provided on one side of a road for irradiating a near-infrared laser beam having a polarization characteristic to the other side of the road. An appropriate number of reflecting mirrors provided to reflect the laser beam emitted from the light emitting unit, and an appropriate number of reflecting mirrors provided on one side of the road irradiate the road surface of the road, and the reflected light is reflected. An appropriate number of light receiving sections for receiving the scattered light or reflected light, and a processing section for processing the scattered light or reflected light received by the appropriate number of light receiving sections, and the light emitting section emits a laser beam. A light-emitting element and an optical lens that allows a laser beam to pass therethrough. The light-receiving unit collects scattered light or reflected light, and a scattered or reflected light collected by the light-collecting lens is referred to as a P-wave. S
A P / S ratio calculation unit configured to calculate a P / S ratio based on a P wave and an S wave, the processing unit including a polarization component beam splitter configured to polarize the light into two polarization components of a wave; P / S ratio set value / memory for storing ratio set value and 1
The P / S ratio set value stored in the memory is compared with the actual P / S ratio calculated by the P / S ratio calculating means to determine whether the P / S ratio is wet, dry, or frozen. And comparison determining means.

According to the method and the apparatus for measuring the road surface condition of the present invention according to the first and second aspects of the present invention, from the light emitting portion provided on one side of the road to the appropriate number of reflecting mirrors provided on the other side of the road. A near-infrared laser beam having polarization characteristics is projected. The scattered light or reflected light reflected by the appropriate number of reflecting mirrors is applied to the road surface of the road, reflected at an appropriate number of locations, and then collected by the appropriate number of light receiving units provided on one side of the road. The light is condensed by a lens and is independently polarized into an S-wave and a P-wave by a polarization beam splitter.

The independently polarized S wave and P wave are taken into the P / S ratio calculating means of the processing section, and the actual P / S ratio is calculated. The calculated actual P / S ratio is taken into the comparison / judgment means, and P / S
S ratio set value / P set and stored in memory in advance
Since the / S ratio set value is taken in, the actual P / S ratio value and the P / S ratio set value are compared and determined, and the wet, dry, and frozen state of the road surface is accurately measured.

Since the light projecting unit, the light receiving unit and the processing unit are provided on one side of the road, it is easy to attach an electric cable for connecting the light projecting unit and the light receiving unit to the processing unit.
Control signals are easily synchronized. Also, reflecting mirrors,
When a plurality of light receiving sections are provided, a plurality of scattered lights or reflected lights are reflected on the road surface of the road and received by the plurality of light receiving sections, so that multipoint measurement is performed. Thus, a wide range of measurement can be performed, and more accurate road surface condition data can be obtained.

[0012]

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

Referring to FIG. 1, a road surface condition measuring device 1 is shown.
A pillar 3 is provided upright on one side of the road R (the right side in FIG. 1), and a light emitting unit 5 and an appropriate number (one in this example) of light receiving units 7 are provided above the pillar 3. 9 are provided. On the other hand, on the other side of the road R (the left side in FIG.
A reflection box 15 provided with an appropriate number (one in this example) of reflection mirrors 13 is provided above the column 11. A processing unit 17 is provided on one side of the road R, and the light emitting unit 5 and the light receiving unit 7 are connected to the processing unit 17. The reflection box 15 is provided with, for example, a solar cell to prevent the surface of the reflection mirror 13 from freezing.

With the above configuration, when a near-infrared laser beam having a polarization characteristic is projected from the light projecting unit 5 toward the reflecting mirror 13, the laser beam is reflected by the reflecting mirror 13 and then reflected on the road surface of the road R. Is irradiated. The scattered light or reflected light is received by the light receiving section 7. This light receiving unit 7
As shown in FIG. 2, P-waves and S-waves, which are two orthogonal polarization components, which are described later in detail, are independently received, and the output ratio is processed by the processing unit 17 to wet the road surface on the road R. , Thirst and freezing will be measured.

As shown in FIG. 3, a pulse laser diode (PLD) 19 having a high output and a wavelength of 880 nm, which is a preferable high-output light-emitting element, is provided in the light projecting section 5 as shown in FIG. Is provided. This P
A PLD drive circuit 21 for emitting light from the PLD 19 is connected to the LD 19. Also, an auto power control circuit 23 for controlling the power of the PLD 19
Are connected to the PLD 19 and the PLD drive circuit 21. A plurality of convex lenses 25 as optical lenses are provided in front of the PLD 19 (left side in FIG. 3).

The light emitting section 5 has a light emitting diode (LE) having a wavelength of 670 nm for emitting monitor light composed of visible light.
D) 27, and this LED 27 has an LED
An LED drive circuit 29 for driving the LED 27 is connected. A convex lens 31 of an optical lens is provided in front of the LED 27 (to the left in FIG. 3).

With the above configuration, when the PLD drive circuit 21 is driven, the PLD 19 emits light. By driving the auto power control circuit 23, the power of the PLD 19 is controlled to emit a pulse laser beam from the PLD 19, and the light passes through the plurality of convex lenses 25. The light is emitted to the reflection mirror 13 provided on one side of the road R.

On the other hand, the LED drive circuit 29 is driven to emit the LED 27, and the monitor light is irradiated from the LED 23 through the convex lens 31 to the reflection mirror 13.

As shown in FIG. 4, the light receiving section 7 is provided with a polarizing beam splitter 33, and the polarizing beam splitter 33 includes a half mirror 33M having 45 mirrors.
It is built in at an angle. A condenser lens 3 is provided in front of the polarization beam splitter 33 (to the left in FIG. 4).
5, a concave lens 37 is provided.

A convex lens 39, a polarizing plate 41, a band-pass filter 43, and an avalanche photodiode (APD) 45 are provided behind the polarizing beam splitter 33 (rightward in FIG. 4). This AP
The amplification device 47 is provided behind the D45, and a high-voltage power supply 49 is connected to the amplification device 47.

4, a convex lens 51, a polarizing plate 53, a band-pass filter 55 and an APD 57 are provided below the polarizing beam splitter 33 in FIG. Below the APD 57, a power amplifier 59 is provided, and a high voltage power supply 61 is connected to the power amplifier 59.

The light receiving section 7 is provided with an LED 63 for emitting monitor light composed of visible light.
LED driving circuit 6 for driving LED 63
5 is connected. A convex lens 67 of an optical lens is provided in front of the LED 63 (left side in FIG. 4).

With the above configuration, the high voltage power supplies 49 and 61 are
N is kept in a state where the width increasing devices 47 and 59 are operated. Then, the scattered light or the reflected light reflected on the road surface of the road R is condensed by the condenser lens 35 and is taken into the polarization beam splitter 33 via the convex lens 37.

In the polarization beam splitter 33, the P-wave of the laser beam is reflected by the half mirror 33M, passes through the convex lens 51, the polarizing plate 53, and the band-pass filter 55, and is detected by the APD 57. And is taken into the processing unit 17.

In the polarization beam splitter 33, the S wave of the laser beam passes through the half mirror 33M, passes through the convex lens 39, the polarizing plate 41, and the band pass filter 43, and is detected by the APD 45. The width is increased at 47 and is taken into the processing unit 17.

The LED 27 driven by the LED drive circuit 29 emits light through the convex lens 31 and the monitor light is applied to the road surface of the road R via the reflection mirror 13.
The LED driven by the LED driving circuit 65
The light is irradiated from 63 to the road surface of the road R via the convex lens 67. The monitor light emitted from the LED 27 to the road surface and L
By matching the monitor light emitted from the ED 63 to the road surface, it is possible to confirm that the laser beam is reliably emitted to the road surface of the road R.

As shown in FIG. 5, the processing section 17 includes a CPU 67. The CPU 67 includes the PLD drive circuit 21 and the LD drive circuits 29 and 65.
Is connected. The CPU 67 is connected with input means 69 such as a keyboard for inputting various data and output means 71 such as a CRT for outputting various data.

A P / S ratio set value / memory 73 is connected to the CPU 67. The P / S ratio set value / memory 73 stores a P / S ratio set value as shown in FIG. In addition, the CP
The P / S ratio calculation means 75 and the comparison judgment means 77 are connected to U67.

The P wave detected by the light receiving section 7 is amplified by an amplifier 7
9, via the sample / hold circuit 81 and the A / D converter 83, are taken into the P / S ratio calculating means 75. Similarly, the S wave detected by the light receiving unit 7 is supplied to an amplifier 85, a sample / hold circuit 87, and an A / D converter 89.
Through the P / S ratio calculation means 75.

The P / S ratio calculating means 75 calculates an actual P / S ratio value based on the taken P-wave and S-wave. The actual P / S calculated by the P / S ratio calculating means 75
The S ratio value is taken into the comparison judging means 77. Since the data shown in FIG. 2 stored in the P / S ratio set value / memory 73 have already been taken into the comparison judging means 73, the actual P / S ratio value is set to the set value shown in FIG. Is determined, and it can be determined that the road surface condition of the road R corresponds to any of the three types of wet, dry, and frozen. By outputting this measurement result to, for example, the output means 71 provided on the side of the road R, the driver can be immediately informed, the driver can be alerted, and the prevention of an accident can be suppressed. .

Further, since the light projecting unit 5, the light receiving unit 7 and the processing unit 17 are provided on one side of the road R, an electric cable for connecting the light projecting unit 5, the light receiving unit 7 to the processing unit 17 is provided. Can be easily performed, and control signals can be easily synchronized. In particular, it is useful on roads where overhead wiring is not possible. Further, when a plurality of reflection mirrors 13 and a plurality of light receiving sections 7 are provided, a plurality of scattered or reflected lights are reflected on the road surface of the road R and received by the light receiving section 7, so that multipoint measurement is performed. Measurement can be performed, and more accurate road surface condition data can be obtained.

The present invention is not limited to the above-described embodiment, but can be embodied in other modes by making appropriate changes.

[0033]

As will be understood from the above embodiments of the present invention, according to the first and second aspects of the present invention, the light emitting unit provided on one side of the road is provided on the other side of the road. A near-infrared laser beam having a polarization characteristic is projected onto an appropriate number of reflecting mirrors. The scattered light or reflected light reflected by the appropriate number of reflecting mirrors is reflected at an appropriate number of places on the road surface of the road, and then is condensed by an appropriate number of light receiving lenses provided on one side of the road. The light is independently polarized into the S wave and the P wave by the polarization beam splitter.

The independently polarized S wave and P wave are taken into the P / S ratio calculating means of the processing section, and the actual P / S ratio is calculated. The calculated actual P / S ratio is taken into the comparison / judgment means, and P / S
S ratio set value / P set and stored in memory in advance
Since the / S ratio set value is taken in, the actual P / S ratio value and the P / S ratio set value are compared and determined, and the wet, dry, and frozen state of the road surface can be accurately measured. .

Since the light projecting unit, the light receiving unit and the processing unit are provided on one side of the road, it is possible to easily attach an electric cable for connecting the light projecting unit and the light receiving unit to the processing, and to control the electric cable. Signal synchronization can be easily performed. Further, when a plurality of reflecting mirrors and a plurality of light receiving sections are provided, a plurality of scattered lights or reflected lights are reflected on the road surface of the road and received by the plurality of light receiving sections, so that multipoint measurement can be performed. Thus, a wide range of measurements can be made, and more accurate road surface condition data can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view of an example in which a road surface condition measuring device of the present invention is installed on a road.

FIG. 2 is an explanatory diagram of a measurement principle for measuring a road surface state of a road with a laser beam.

FIG. 3 is an explanatory diagram illustrating a configuration of a light projecting unit.

FIG. 4 is an explanatory diagram illustrating a configuration of a light receiving unit.

FIG. 5 is a configuration block diagram of a processing unit included in the road surface condition measuring device of the present invention.

FIG. 6 shows a P / S ratio set value and a P / S ratio stored in a memory.
It is a figure showing an example of an S ratio set value.

[Explanation of symbols]

 Reference Signs List 1 Road surface condition measuring device 5 Light emitting unit 7 Light receiving unit 13 Reflecting mirror 17 Processing unit 19 Pulse laser diode (PLD) 27 LED 33 Polarizing beam splitter 35 Condensing lens 45, 57 Avalanche photodiode (APD) 73 D / S ratio Set value / memory 75 P / S ratio calculation means 77 Comparison judgment means

Claims (2)

(57) [Claims] 1. A near-infrared laser beam having a polarization characteristic is projected from a light projecting portion provided on one side of a road to an appropriate number of reflecting mirrors provided on the other side of the road, and the reflected light is reflected. The laser beam reflected by the mirror is applied to the road surface of the road, and the scattered light or the reflected light thereof is converted into two polarized components, S waves, which are orthogonal to each other by an appropriate number of light receiving units provided on one side of the road. Independently received as P-waves, the actual P / S ratio of the received S-wave and P-wave is compared with a preset P / S ratio set value, and the wetness, dryness and freezing condition of the road surface are measured. A method of measuring a road surface condition. 2. A light projecting unit provided on one side of a road for irradiating a near-infrared laser beam having a polarization characteristic, and the laser beam projected on the other side of the road from the light projecting unit. An appropriate number of reflection mirrors for reflecting light, and an appropriate number of light receiving units provided on one side of the road for irradiating the road surface of the road from the appropriate number of reflection mirrors and receiving the reflected scattered light or reflected light. And a processing unit for processing scattered light or reflected light received by the appropriate number of light receiving units, and the light projecting unit is constituted by a light emitting element that emits a laser beam and an optical lens that allows the laser beam to pass. A light-collecting lens for condensing scattered light or reflected light by the light-receiving portion, and scattered or reflected light condensed by the light-collecting lens into P-wave and S-wave.
A P / S ratio calculation unit configured to calculate a P / S ratio based on a P wave and an S wave, the processing unit including a polarization component beam splitter configured to polarize the light into two polarization components of a wave; A P / S ratio set value / memory for storing the ratio set value,
The P / S ratio set value stored in the memory is compared with the actual P / S ratio calculated by the P / S ratio calculating means to determine whether the P / S ratio is wet, dry, or frozen. A road surface condition measuring device, comprising: a comparison determining unit.