JPH1121834A - Road surface freeze judgment method - Google Patents

Abstract

(57) [Problem] To provide a road surface freezing determination method capable of accurately determining the freezing state of a road surface even when a deicing agent is sprayed. SOLUTION: A temperature sensor 8 for detecting a road surface temperature and a wetness sensor 9 for detecting a wet state of the road surface are installed, and a time transition of these measured values is measured to determine whether or not the road surface is frozen. Things.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frozen state determination method used for predicting a frozen state of a road such as a road or the like.

[0002]

2. Description of the Related Art Conventionally, road surface freeze determination methods are mainly divided into two methods.

[0003] The first method has a sensor for measuring the outside air temperature and the road surface temperature, and determines whether or not the road surface is frozen based on the sensor information. As a means for measuring the outside air temperature and the road surface temperature, a general thermometer and a thermocouple are mainly used.Especially at the road surface temperature, even when using a radiation thermometer utilizing the natural radiation of infrared rays from the road surface, is there.

The second method is to irradiate a road surface with infrared rays or radio waves, and determine the presence or absence of freezing based on a difference in reflectance from the road surface. This method uses an infrared irradiation device, a light receiving device, and a signal processing device near the road, and uses the fact that the intensity of the reflected light (reflected radio wave) that irradiates and reflects on the road differs between dry and wet road surfaces. To detect. Also,
A mixture of the above two methods has also been proposed.

[0005] Specifically, as shown in FIG.
Irradiates infrared rays 3 from the road surface wetness meter 2 to the road surface 1
The signal processing and road surface wet / freeze determination output unit 7 calculates the ratio between the component that does not return to the incident direction (specular reflection wave 4) and the component that returns to the incident direction (diffuse reflection wave 5) among the reflected waves from. The surface measured by the infrared radiation thermometer 6 which measures the road surface wetness (the degree of wetness of the road surface is grasped by the strength of this ratio), further measures the amount of infrared radiation from the road surface, and measures the surface temperature of the road surface The threshold value required for the determination is set based on the temperature (for example, the surface temperature is set to 0 ° C. or less), and when the road surface is wet, the signal processing and the road surface wet / freeze determination output unit 7 determine whether or not the road surface is frozen. It is to judge.

[0006]

However, the temperature,
The measurement of the road surface temperature alone cannot always accurately detect the frozen state. When a deicing agent is sprayed on the road, the temperature at which the frozen state changes depends on the situation. Therefore, when the temperature threshold is simply set (for example, to 0 ° C. or less) and the determination is performed, the freeze determination is performed. Errors and large errors will result.

[0007] The temperature at which the ice actually freezes is determined by the amount of the antifreeze applied and the wet state of the road surface, so that it is difficult to grasp in advance. Furthermore, a method for accurately measuring the amount of the antifreeze applied and the wet state has not yet been established.

Accordingly, an object of the present invention is to solve the above problems and to provide a road surface freezing determination method capable of accurately determining the freezing state of a road surface even when a deicing agent is sprayed.

[0009]

In order to achieve the above object, the present invention provides a temperature sensor for detecting a road surface temperature and a wetting sensor for detecting a wet state of the road surface, and a time sensor for measuring these values. It is to determine the presence or absence of freezing of the road surface by measuring the target transition.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

Regarding the principle of the present invention, an example of a system configuration will be described first, and then an outline of operation will be described.

FIG. 1 shows an example of a system configuration according to the present invention.

This system comprises a road surface temperature sensor 8, a road surface wetness sensor 9, and an arithmetic output device 10. The road surface temperature sensor 8 measures the road surface temperature, and for example, a general radiation thermometer is used.

As the road surface wetness sensor 9, a sensor using a conventionally used infrared reflectance measuring method may be used. These measurement data (surface temperature of the target road,
The presence or absence of wetness on the road surface) is measured at regular time intervals, and these measurement data are collectively processed to determine and output the presence or absence of freezing.

Next, the freeze determination algorithm will be described in detail.

FIG. 2 is an example of a time-dependent change in the road surface temperature during freezing measured on an actual road. At the bottom of the graph, the change in the road surface condition at the time of measurement (presence or absence of a frozen state) is also shown.

The example of FIG. 2 shows a case where the deicing agent is not sprayed on the road surface. The road surface temperature decreases with time, and thereafter becomes constant at about 0 ° C. for a certain time, and tends to decrease again. Show. That is, the temperature change width Δt based on 0 ° C. is substantially zero.

FIG. 3 shows a deicing agent (sodium chloride 10
0g) shows an example of a time-change characteristic of the road surface temperature when sprayed.

In the example of FIG. 3, the same tendency as in the case where the above-mentioned antifreezing agent is not sprayed is shown, but the temperature value at which the temperature becomes a constant temperature is below the freezing point (in this example, about -10 ° C.). . That is, the temperature change width Δt based on 0 ° C.
Is approximately 10 ° C.

FIG. 4 shows the relationship with the temperature change width Δt when the amount of the antifreezing agent (sodium chloride) applied is changed.

Since the spray amount and the temperature change width Δt are substantially proportional to each other, the spray amount of the antifreeze can be determined by measuring the temperature change width Δt.

FIG. 5 shows the time course of the road surface temperature when the antifreezing agent is sprayed.

In the present embodiment, there is an effect of spraying, and it has not been frozen. In such a case, the temperature does not become constant.

From the above experimental results, that is, even if the spray amount of the deicing agent is unknown, the present invention detects the time transition characteristic of the road surface temperature and identifies the presence or absence of a constant temperature section. It is possible to determine the presence or absence of a frozen state.

In order to realize the present algorithm, FIG.
The road surface data measured at intervals of several minutes is stored in the memory in the arithmetic output device 10, and the difference between the temperature value at the certain point and the temperature value at the next point is compared. Is detected. If this temperature change width is within the range of the measurement error of the temperature sensor, it is determined that it is constant, and when the constant temperature difference and time become equal to or greater than a preset value, it is determined that the temperature has frozen.

[0026]

In summary, according to the present invention, by detecting the transition of the road surface temperature, the detection accuracy of the road surface freezing determination can be remarkably improved as compared with the conventional method, regardless of whether or not the antifreezing agent is sprayed.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of the present invention.

FIG. 2 is a diagram showing an example of a time change characteristic of a road surface temperature at the time of freezing (without spraying an antifreezing agent) in the present invention.

FIG. 3 is a diagram showing an example of a time change characteristic of a road surface temperature at the time of freezing (with antifreeze sprayed) in the present invention.

FIG. 4 is a graph showing the relationship between the amount of sprayed antifreeze and the temperature change width.

FIG. 5 is a diagram showing an example of a time change characteristic of a road surface temperature when an antifreezing agent is sprayed and not frozen in the present invention.

FIG. 6 is a schematic diagram showing a conventional method.

[Explanation of symbols]

 8 temperature sensor 9 wetness sensor 10 arithmetic output device

Claims (1)

[Claims] 1. A temperature sensor for detecting a road surface temperature and a wetness sensor for detecting a wet state of the road surface are installed.
A road surface freezing determination method characterized by determining the presence or absence of road surface freezing by measuring the temporal transition of these measured values.