JPS584003A - Apparatus for distinguishing road condition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a road surface condition identification device in which a traffic counter device is added by adding a signal processing stage without changing the equipment configuration of the current road surface condition identification device.

Ensuring the safety of drivers by taking appropriate measures against traffic disturbances caused by frozen roads, snow accumulation, etc. is a very important issue in transportation system management, and in order to take appropriate measures, It is necessary to quickly and accurately grasp the road surface condition. The inventor has developed 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, and a light receiver that receives visible light and diffusely reflected light from the road surface as devices that satisfy the above requirements. A road surface condition detector equipped with a light receiver that receives diffusely reflected infrared light, a comparator that discriminates the outputs of these light receivers at respective required levels, and a discrimination device that discriminates the road surface condition based on the discrimination results. Invented an identification device and applied for it (patent application 1984-804)
29).

This invention is based on the current road surface condition identification device, that is, the patent application filed in 1973.
The object of the present invention is to provide a road surface condition identification device that detects a vehicle through one software process without changing the equipment configuration of the device of No. 5-80429, has a traffic counter function, and prevents malfunctions.

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

In FIG. 1, a pillar 22 is erected on one side of a road 21, and a support arm 23 extends upward from the upper end of the pillar 22 toward the upper side of the road 21. A light projector 24, a diffuse reflection receiver 25, and a specular reflection receiver 26 are attached to this support arm 23.
and a light emission level measuring device 27 are installed, respectively.
A road surface temperature gauge 28 is provided on the pillar 22. The light projector 24 uses a mercury lamp whose emission spectrum includes not only visible light but also near-infrared light. The projector 24 is arranged so as to be directed toward the road surface at an appropriate angle of incidence. The specular reflection receiver 26 receives specularly reflected visible light of the road surface reflected light projected from the light projector 24 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. The wavelength of near-infrared light is approximately 1.5 to 2.
Preferably, the thickness is in the range of 5 μm. Light emission level measuring device 2
7 directly receives the light from the floodlight 24;
In this embodiment, the amount of visible light is measured. A radiation thermometer is used as the road surface thermometer 28.

In FIG. 2, the projector 24 is driven by a constant power ballast 29 with constant power. The diffuse reflection light receiver 25 includes light receiving elements 31, 32'iH for infrared light and visible light, and the outputs of these light receiving elements 31, 32 are amplified by an amplifier 34, and then
Each noise component is removed by a bandpass filter 35.

The specular reflection light receiver 26 includes a visible light light receiving element 33, and the output signal of this light receiving element 33 is also outputted via an amplifier 34 and a bandpass filter 35. The signals output from the photoreceivers 25, 26 are again amplified and rectified by the amplifiers 36 and sent to the comparators j1, 42, and 43, respectively. Each of these comparators 41, 42, 43 has two or more reference levels AI, A2 . Bl, B2゜B3. B4,
01, 02 are set, and each light receiving element 31, 32 .
The outputs of 33 are compared by these reference levels. The logic circuit 44 converts these comparison results into status signals, and the output of the logic circuit 44 is sent to the arithmetic processing section 45. As the arithmetic processing section 45, a microprocessor is suitably used.

Further, the comparators 41, 42, 43, the logic circuit 44, and the arithmetic processing section 45 may all be a one-chip microprocessor with a built-in V cape converter, or a combination of a width converter and a microprocessor.

The light emitting level measuring device 27 includes a visible light light receiving element 30, and the output of this light receiving element 30 also passes through an amplifier 37, a bandpass filter 38, and is amplified and rectified by an amplifier 39. Input to comparators 41, 42 and 43. Comparator 41
, 42.43 of the above reference levels At, A2. Bl,B
2. B3. B4°01.02 is adjusted by the output of the measuring device 27. Although the projector 24 is driven with constant power, the amount of light emitted varies depending on the quality of the mercury lamp itself, dirt on the front surface of the projector, etc. If the projector changes, the amount of light reflected from the road surface will naturally change, so if the reference levels of the comparators 41, 42, and 43 are kept constant, false detection may occur. Here, in order to compensate for changes in the amount of projected light, the comparators 41, 42 .
43 standard levels are adjusted. Since the amount of projected light and the amount of reflected light are considered to be approximately proportional, each comparator 41, 4
The reference level of 2°43 is changed in proportion to the level of the amount of light emitted. ``The output of the thermometer 28 is input to the arithmetic processing section 45.

Figure 3 shows the relationship between dry, wet, snowy and frozen conditions.
The relative ranges of the output levels of each of the light receivers 25, 26 and thermometer 28 and the determination results of the road surface condition obtained from these outputs are shown.

Now, if we consider the case where a vehicle enters the road surface condition identification area, the specular reflection component is blocked by the vehicle, so the output of the specular reflection receiver 26 is 0 (actually, there is an offset, so the output is shown in FIG. 3). The level becomes C2) near O. Further, the output of the diffuse reflection receiver 25 increases greatly because the light is reflected by the vehicle (level B4 in FIG. 3). Furthermore, since the road surface thermometer 28 uses an infrared radiation thermometer, vehicle detection can also be performed using this. That is,
In order to measure road surface temperature with a radiation thermometer, it is necessary to correct the emissivity of the object.For asphalt or concrete, this emissivity is set to about 0.98, but the steel plate of a vehicle has a low emissivity. Therefore, (about 0.9)
The apparent temperature output decreases. Therefore, vehicle detection can be performed by detecting the above three changes.

The traffic counter and malfunction prevention function of the present invention are executed as follows. Comparator 42 in FIG.
A vehicle detection reference level B 4°C2 is set in 43, and a vehicle detection reference value I of the road surface temperature difference (previous temperature - current temperature) is set in the arithmetic processing section 45.

The output of each light receiver 25.26 is the vehicle detection level B4. of the comparator 42.43. It is discriminated by C2, and a status signal representing the discrimination result is outputted via a logic circuit. Based on this status signal, the arithmetic processing unit 45 detects the entry and passage of vehicles and counts the number of passing vehicles according to the following procedure.

Referring to FIG. 4, first check whether the output of the specular reflection receiver 26 is below the reference level C2 (step 1m)
. If it is below the reference level C2, it is assumed that a vehicle has entered and the timer is set to a predetermined time (step 1b), and on the condition that the timer does not go up (step lc), the blade of the specular reflection receiver 26 exceeds the reference level C2 again. (step ld). Standard level C2 before timer up
If it exceeds the reference level C2, it is determined that the vehicle has passed and the process proceeds to step 5. If the timer is fL without exceeding the reference level C2, it is assumed that no vehicle has entered and the process proceeds to step 2a. If the specular reflection receiver output is not below the reference level C2 in step 1a, proceed to step 2a.6 Next, in step 2 (28 to 2d), based on the visible light output from the diffuse reflection receiver 25, the reference level B4 is set. Based on the discrimination result, it is determined whether the vehicle has passed. The procedure is the same as step 1 (18 to ld) except that in step 1a, 1≦C2'' is replaced with 1>B4'', and in step 1d, 1<C2'' is replaced with 1<B4''. .Step 3 (3
In steps 8 to 3d), instead of determining whether the road surface temperature decrease is equal to or lower than the reference level C2 in step 1a, it is determined whether the road surface temperature decrease is equal to or higher than the reference value 1. The same steps as Step 1 are performed except that instead of determining whether the temperature rise value returns to above the reference level C2, it is determined whether the temperature increase value is equal to or greater than the predetermined value 1 (Step 3d). If the vehicle passage is not determined in steps fl-3, road surface conditions are identified (step 4). Step 1~
3, when it is determined that the vehicle has passed, the vehicle counter is incremented by 1 without determining the road surface condition (
Ste, Gu5). The amount of passing vehicles counted over an appropriate period of time is sent to a center or a road surface display device installed on the road, etc., where the traffic amount is monitored and displayed.Meanwhile, the vehicle counter is cleared and the next count starts. Be prepared.

The procedure for determining the road surface condition is described in the above-mentioned patent application No. 55-80429.
However, it will be explained below with reference to FIGS. 3 and 5.

As shown in FIG. 3, the light receiver 25
．． 26 output levels change and each state has its own range ◎ Therefore, the reference level A1 is set to a level that can distinguish between dry state and other states (dry state and part of snowy state (new snow)) ), the reference level B1 is set to a level that can distinguish between white snow (fresh snow) and other conditions, and the reference level B2 is set to a level that can distinguish snowy and dry conditions from other conditions according to level B1, Set the reference level C1 to a level that can distinguish between the mirror-surfaced wet state and other states (although the #i-surfaced wet state and the snowy state that appear white overlap), A2. , B3 are set to a level (A2=83 in this embodiment) that can distinguish between normal and abnormal sensors.

Each receiver 25.26 has a comparator 4], 42.43
Reference levels A I , A 2 , B as above of
1, B2°B3,01, and 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 procedure, outputs a road surface state identification signal of dry, wet, snowy, or frozen, or performs sensor abnormality processing. Fifth
Referring to the figure, first, each light receiver 25, 26 and thermometer 2
8 is checked for any abnormality (step 10), and if there is no abnormality, the process proceeds to step 11. If there is an abnormality, the process moves on to deal with it (step 15). In step 11, based on the infrared light output of the diffuse reflection receiver 25, it is determined whether the road surface condition is dry or other than dry based on the discrimination result based on the reference level A1. That is, if the infrared light output of the light receiver 25 is equal to or higher than level A1, it is considered as drying, and if it is less than level A1, it is considered as other than drying. The area determined to be dry includes part of the snowfall, that is, fresh snow (white snow).

Next, the process proceeds to steps 12 and 16, in which snowfall is determined using the visible light diffused reflection output. The snow included in the snow determined to be dry in step 11 is white snow, and in the case of this white snow, the visible light diffused reflection output is level B1 or higher. Therefore, among the snow determined to be dry in step 11, if the level is B1 or higher, it is determined to be snow, and if it is less than B1, it is determined to be dry (step 16). .

Further, among the items determined to be other than dry in step 11, those whose visible light diffuse reflection output is level B2 or higher are determined to be snowfall, and those whose visible light diffuse reflection output is level B2 or higher are determined to be wet or frozen (step 12).

In step 13, the wet state (
(mirror surface).

If the visible light specular reflection output is equal to or higher than level C1, it is in a wet state.

In the determination process of steps 11-13, a frozen state and a part of a wet state are not determined. Therefore, in Step 14, frozen and wet conditions are distinguished based on the output of the thermometer 28. If the road surface temperature is 0°C or higher, it is wet, and if it is -2°C or lower, it is frozen. When the road surface temperature is between 0° C. and -2° C., if the previous determination was wet, it is determined to be wet, and if it is frozen, it is determined to be frozen (step 18).

Even if it is determined in step 14 that the area is frozen, the area may still be in a wet state. This is the case when snow melting agents are sprayed. Spraying a snow melting agent lowers the freezing point, causing a transition from a snowy or frozen state to a wet state. Therefore, even if it is determined in step 14 that the area is frozen, the wet state is maintained within a certain period of time (the effective time of the snow melting agent) after the snow melting agent is sprayed (step 17). Detection of snow melting agent dispersion can be performed in various ways. For example, a switch is provided for the spraying staff to operate, an oscillator is provided on the snow melting agent spraying vehicle, a receiver is provided on the road surface condition identification device, and the receiver detects the passage of the spraying vehicle, and specular reflection of visible light is provided. Check the fluctuation of the received light output.

There are other ways to do this. When snow or ice melts and turns into water, the road surface temporarily becomes mirror-like.

As a result, the visible light specular reflection output increases, so it can be known that the snow melting agent has been sprayed.

When the road surface condition is finally determined in this way, a road surface condition identification signal is output (step 19).

This identification signal, together with the traffic volume counted in steps 1 to 5, is transmitted to, for example, a center or a road surface display device installed on the road, and the road surface condition and traffic volume are monitored and displayed. The above road surface condition determination is performed at appropriate time intervals. In addition, each standard level A above
1. A2. Bl.

B2. B3. B4. CI, C2 and reference temperature (
0°C, -2°C) and the reference temperature difference I vary depending on the installation location, so it is preferable to make them variable and change them as appropriate.

In the embodiments described above, the traffic volume measurement and road surface condition determination are performed by the arithmetic processing unit (microprocessor, controller), but these measurements and determination can also be performed by a logic circuit. Furthermore, the setting of the reference level that is the basis for measurement or discrimination and the method of combining the compared and discriminated status signals are not limited to the above example, but may be determined as appropriate depending on the traffic volume or road surface condition to be measured or discriminated. can.

As described above, according to the present invention, without changing the equipment configuration of the current road surface condition identification device, by adding only the signal processing stage, and especially by changing the program of the microprocessor part, Since a traffic counter function can be added, IC,
Current equipment can be modified with relatively simple operations such as replacing modules or cards. In addition, since road surface condition identification is not performed when the vehicle enters the road surface condition identification area, it is possible to prevent the identification device from malfunctioning due to misidentifying the roof of the vehicle as the road surface and performing road surface condition identification.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram showing the arrangement of the emitter and receiver;
Figure 2 is a diagram showing the internal configuration of the road surface condition identification device, Figure 3 is a diagram showing the relative range of the output level of each light receiver for each road surface condition, and Figure 4 is a diagram showing the relative range of the output level of each light receiver for each road surface condition. Flowchart showing the procedure. FIG. 5 is a flowchart showing the procedure for determining the road surface condition. 24... Emitter, 25... Diffuse reflection receiver, 26...
Specular reflection receiver, 28...Road surface thermometer, 41.42°4
3... Comparator, 45... Arithmetic processing unit. Patent applicant Tateishi Electric Co., Ltd. Representative patent attorney Tatsuo Ito Representative patent attorney Tetsuya Ito

Claims (1)

[Scope of Claims] 1. A 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, and diffusely reflected infrared light from the road surface. It is equipped with a light receiver that receives light, a comparator that discriminates the outputs of these light receivers at required levels, and a discrimination device that discriminates the road surface condition based on the discrimination results. Passage of a vehicle is identified based on whether the reflected output is greater than a predetermined value, or the diffusely reflected output of visible light is less than a predetermined value, and whether these changes occur within a predetermined time. A road surface condition identification device that includes a traffic counter that counts the amount of traffic. 2. A road surface condition identification device that includes a road surface temperature meter, and detects the passing of a vehicle based on the indication of the road surface temperature meter changing by a predetermined value or more and within a predetermined time. A road surface condition identification device according to claim 1, characterized in that: