JPS6152932B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for identifying road surface conditions as dry, wet, snowy, frozen, etc., and is an improvement of the invention related to the earlier application, Japanese Patent Application No. 80429/1983.

An object of the present invention is to provide the device described at the beginning, which can prevent malfunctions caused by a vehicle entering the sensor output area.

Next, a preferred embodiment of the present invention will be described with reference to the drawings.

Since FIG. 1 and FIG. 2 are the same as those of the prior application mentioned above, they will be briefly explained. In Fig. 1, 21 is a road, 22 is a support column, 23 is a support arm, 2
4 is a light emitter, 25 is a diffused reflection receiver, 26 is a regular reflection receiver, 27 is a light emission level measuring device, and 28
is a road surface thermometer. The light projector 24 uses a mercury lamp whose spectrum includes not only visible light but also near-infrared light. The specular reflection receiver 26 receives specularly reflected visible light and converts it into an electrical signal.
The diffused reflection receiver 25 separately detects visible light and near-infrared light reflected from the road surface. A radiation thermometer is used as the road surface thermometer.

In FIG. 2, 29 is a constant power type ballast, which drives the projector 24 with constant power. The diffuse reflection light receiver 25 includes light receiving elements 31 and 32 for infrared light and visible light, and 34 is the light receiving element 31 and 3.
An amplifier 2 amplifies the output of the amplifier 34, and a band filter 35 removes noise components from the output of the amplifier 34. The specular reflection receiver 26 is a visible light receiving element 3
3, whose output signals undergo similar processing.
The signals output from the light receivers 25 and 26 are again amplified and rectified by the amplifier 36, and then sent to the respective comparators 41, 42, and 43. The light emitting level measuring device 27 includes a visible light receiving element 30, and its output also passes through an amplifier 37 and a band filter 38, is amplified and rectified by an amplifier 39, and is sent to each comparator 41. , 42, 43. Each comparator 4
1, 42, 43 have reference levels A, B1, B2, B3, B4, C1, 1 to 4 as shown in FIG.
C2 is set, and each set reference level is adjusted by the output of the measuring device 27. The logic circuit 44 converts the comparison results of the comparators 41, 42, and 43 into a status signal, and the output thereof is sent to the arithmetic processing section 45. Note that the output of the thermometer 28 is processed by the arithmetic processing section 4.
Enter 5.

FIG. 3 shows the light receivers 25 and 26 and the thermometer 28 for dry, wet, snowy and frozen conditions.
The figure shows the relative range of output levels and the road surface condition judgment results obtained from these outputs. In this way, the light receiver 2
The output levels of 5 and 26 vary and each state has its own range. Therefore, the standard level (A) is set to a level that can distinguish between dry conditions and other conditions, the standard level B1 is set to a level that can distinguish between white snow and other conditions, and the standard level B2 is set to a level that can distinguish between snow and dry conditions. The reference level C1 is set to a level that can distinguish between the wet state and other states. The reason why 0°C and -2°C are set as the reference temperatures of the road surface temperature is because it is thought that freezing starts at -2°C and melting starts at 0°C.

Each light receiver 25, 26 has a comparator 41, 42, 4
3. Discriminated by the above reference level,
A status signal representing the discrimination result is output. Based on this state signal, the arithmetic processing unit 45 determines the road surface state according to the following exemplary procedure, and outputs a road surface state identification signal of dry, wet, snowy, and frozen. Therefore, to briefly explain Fig. 4, first, if the diffusely reflected visible light receiver output (SC/VIS) is smaller than level B4, the sensor abnormality processing is performed,
On the other hand, for those judged to have no abnormality,
Diffuse reflection infrared light receiver output (SC/IR) is level A
If it is not smaller, the diffusely reflected visible light receiver output (SC/VIS) is compared with level B1, and based on the judgment shown in the figure, each state of dryness or snowfall is output processed. On the other hand, if the diffusely reflected infrared light receiver output (SC/IR) is smaller than level A, the next step is to compare the diffusely reflected visible light receiver output (SC/VIS) with level B2, and on the other hand, to determine snow accumulation. On the other hand, in the next step, the specular reflection visible light receiver output (NOR) is compared with level C1, and if it is large, output processing for moisture judgment is carried out, and if it is small, output processing is carried out. , the next step is road temperature output (RT).
is compared with two levels 0° C. and −2° C., and as shown in the figure, output processing for determining wetness or freezing is performed.

By the way, if a vehicle enters the vehicle as a disturbance, the output of the light receiver will naturally be affected, so there is a risk that the road surface condition will be incorrectly identified. Therefore, it is necessary to add an appropriate reference level to avoid the influence of this disturbance. Considering that when the projected light is interrupted by a vehicle, the specular reflection receiver output of visible light decreases rapidly, we have established a lower limit reference level C2. In consideration of the sudden increase in the visible light diffuse reflection receiver output, an upper limit reference level B3 is provided. Furthermore, regarding temperature, since the road surface thermometer is composed of a radiation thermometer, it should be set to the road surface emissivity due to the difference between the emissivity of the road surface (approximately 0.98) and the emissivity of the vehicle body (approximately 0.90). Therefore, by detecting this decrease in road surface temperature, vehicle entry can be detected and the influence of disturbances can be removed. In this way, when a vehicle enters the vehicle, it is sufficient to individually judge the three factors, and an example of the order of each comparison is shown in the flowchart of FIG.

In this example, as a first step, the visible light specular receiver output is compared with the added level C2, and if it is equal to or lower than this, vehicle entry is detected and a road condition identification output is obtained. It ends without. If it is high, as a second step, the output of the diffused reflection receiver is compared with the added level B3, and if it is equal to or higher than this, it is determined that it is a vehicle, and the road surface condition identification output is not obtained. If it is low, the third step is to compare the road surface temperature before a certain period of time (stored in memory) with the current road surface temperature, and if there is a change in decrease, the system also detects the approach of a vehicle. The program ends without obtaining the identification output of the road surface condition. Although not shown in the drawings, when a vehicle is detected, processing for outputting the state may be set before "End".

As described above, according to the present invention, vehicle entry is detected using an existing device for road surface condition identification, and road surface condition identification is not performed when detecting vehicle entry, so that errors in road surface condition identification are avoided. can be reduced.

[Brief explanation of the drawing]

Figure 1 shows the arrangement of the projector and receiver on the road surface, Figure 2 is a block diagram showing the internal configuration of this device, and Figure 3 shows the relative range of the output level of each receiver for each road surface condition. FIG. 4 is a flowchart showing a procedure for road surface condition identification, and FIG. 5 is a flowchart showing an example of detecting the entry of a vehicle. 24 is a light projector, 25 is a diffused reflection receiver, 26 is a regular reflection receiver, 28 is a road surface thermometer, 41, 42, 4
3 is a comparator, and 45 is an arithmetic processing section.

Claims (1)

[Claims] 1. A light projector that projects visible light and infrared light toward the road surface, a light receiver that receives specularly reflected light and diffusely reflected light of visible light from the road surface, respectively, a light receiver that receives diffusely reflected light of infrared light from the road surface, It is equipped with a comparator that discriminates the output of each of these light receivers at a required level, and an identification device that identifies the road surface condition based on the discrimination result of the comparator, and the comparator determines whether the output of the visible light specular reflection light receiver is below a certain level. A road surface condition identification device, characterized in that the road surface condition identification device does not perform road surface condition identification by the identification device in response to determining that the visible light diffuse reflection receiver output is equal to or higher than a certain level.