JPS58158540A - Device for judging road surface condition - Google Patents

Abstract

PURPOSE:To make it possible to detect exactly road surface conditions such as thawing snow, consolidated snow, freezing, etc. on a road by judging whether or not light reflected from a road surface is bieing properly received and performing road surface condition judgement operation. CONSTITUTION:A light emitting device 1 directs on to a road surface 2 a light that is not polarized and the light reflected from the road surface 2 is received in the image dividing lens 7 of a light receiver 3. This light is divided for a light polarizer 8 that detects horizontal polarization component and a light polarizer 9 that detects vertical polarization component. The outputs of light receiving elements 10 and 11 are inputted to an all-wave rectifying, smoothing circuits 18 and 19 through amplification circuits 14 and 15 and narrow band-pass filters 16 and 17. The outputs of the smoothing circuits 18 and 19 are inputted to a processing circuit 23 through an A/D converter 22. On the other hand a comparison circuit 24 identifies the horizontally polarized light component for level by the reference value from a reference value generating circuit 25, and only when this horizontally polarized light output is under the reference value, the processing circuit 23 performs judgement operation for road surface conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus (a) for determining a road surface condition during driving on a road such as an automobile road.

Book I'-I: The inventor here proposes a novel method that can determine road surface conditions while a car is running.

This makes it possible to know road surface conditions such as melting snow, compacted snow, and freezing, and to estimate the extraneous coefficient of the road surface. As a result, it is important to maintain the normal deformation of the vehicle and prevent accidents.

In such a method, it is desirable to accurately detect the road surface condition.

SUMMARY OF THE INVENTION An object of the present invention is to provide a road surface condition determination device that can accurately detect road surface conditions without error.

FIG. 1 is a simplified +et view of one embodiment of the present invention. The light emitting device 1 emits unpolarized light toward one corner of the road surface 2 . The light reflected by the road surface 2 is received by the light receiving device 3. The optical axis of the light emitted by the light emitting device 1 is inclined, for example, by 50° to the left in FIG. It is tilted 50 degrees to the right in Figure 1. The light emitting device 1 includes one or more light emitting diodes 5 and a condensing lens 6. The light receiving device 3 includes an image splitting lens 7, polarizers 8 and 9, and a light receiving element 1 realized by a silicon autodiode or the like.
0 and 11.

Figure 2 shows the light emitting device 1 and the light receiving device? - FIG. 3 is a block diagram of an electric circuit related to L3. The light emitting diode 5 is
It is driven by a oscillator circuit 13 which receives the output from an oscillation circuit 12, and is driven by a oscillator circuit 13 which receives an output from an oscillation circuit 12.
It emits kHz pulsed dimming and its radiation output is 2Q nW. Pulse modulated light emitted from the light emitting device 1 is reflected by the road surface 2 and is received by the image lens 7 of the light receiving device 3.

This received light is passed through a polarizer 8 that detects the horizontally polarized light component.
and a polarizer 9 for detecting the vertically polarized light component, and are applied to the light receiving elements 10 and 11, respectively. Light receiving element 10
．． The output from 11 is amplified by an amplifier circuit 14.15, and a narrow band pass filter 16 passes only the variable axis light.
．． 17 to the aftermath rectifier/smoothing circuits 18 and 19, respectively. Aftermath rectification/smoothing h! i, 418,
] 9 derives a signal having a level 6 relative to the horizontal and vertical polarization components of the reflected light in lines 20 and 21.

The signal from line 20.21 is applied via an analog/digital converter 22 to a processing circuit 23 implemented by a microprocessor or the like.

A signal representing the horizontal polarization component from line 20 is also applied to one input of comparator circuit 24. The other input of the comparison circuit 24 is supplied with a signal from a circuit 25 that generates 3fi of horizontal polarization component reference 11μ.

When the signal from line 20 is equal to or greater than the reference value given from circuit 25, comparison circuit 24 supplies a signal to processing circuit 23 via line 26, indicating that the road surface condition can be determined.

Further, the signal from the detector 27 that detects the outside air temperature is amplified by 11'iit by the amplifier circuit 28 and is applied to one side of the comparison circuit 29. The other input of the comparator circuit 29 is supplied with a signal from a circuit 30 for generating an outside temperature reference value. Comparison circuit 29 indicates that outside air is 11.11 degrees and circuit 3
When the value is equal to or greater than the reference value determined by 0, a signal indicating this is sent to the processing circuit 23 via all lines 31. The processing circuit 23 provides a signal representing the road surface condition to the control/display device 32.

FIG. 3 is a flowchart for explaining the operation of the processing circuit 23. In determining the state of the circuit lTl12, the process moves from step n] to step n2, where the comparator circuit 24
The signal on line 26 is read from.

When FIG. 4 is illustrated, the state of path 111']2 and the relationship between the horizontally polarized light output and 1 (plane polarized light output) are omitted.

In FIG. 4, asphalt represents that the road 1I112 is paved with asphalt, and concrete represents that the road 1I112 is paved with concrete. A indicates that the road surface 2 is dry, B indicates that the road surface has been wiped with rags, and C indicates that water has been sprinkled on it. As can be seen from FIG. 4, the signal-to-noise ratio of the horizontally polarized light 1" is generally better than that of the vertically polarized output. In the comparison circuit 1i24, +'ti '3 representing the horizontally polarized light component passing through the line 20 is converted into the base γ ((level discrimination is performed by the tomoe value), and this horizontally polarized light 1
11 Judgment of the road surface condition described below when the force is above the reference value>;11! l! Take J1 work now. Of course, discrimination can also be made using the vertical surface and one polarization component. In this way, it is determined whether the reflected light from the road surface is received by 1 or not, and for example, whether it is the horizontal 11i+'+ light output,
When it does not have enough level, i.e. hk NU 1
+11*r#, in step n3, the processing circuit 23 maintains the road surface discrimination result f, 'f, or issues a message Y indicating that the present device should be maintained. When the horizontally polarized light output has a level equal to that of light, the process moves from step n2 to step n4, and the ratio between the road surface irregularity rate (2) of the horizontal polarized light component and the road surface irregularity rate (2) of the vertically polarized light component is calculated. Note that this ratio H/V is dependent on the ratio between the level of the horizontal tlnt to C component and the level of the vertically polarized component received by the light receiving element 10.11. The symbols used in the following explanation and the meanings expressed by the notation M are as shown in Table 1. - (Left below) 1st Table processing circuit 23 samples and detects the signal representing the horizontal polarization component from line 20.21 and the signal representing the vertical polarization component at a predetermined fixed time record and performs calculations. Process. Here, j represents the value at each sampling time. As mentioned above, H represents the road surface reflectance of the horizontal polarization component, ■ represents the road surface reflectance of the vertical polarization component, and 0 or γ represents the degree of polarization, which is expressed by the first equation.

Figures 5 and 6 show the ratio H/V and its cumulative frequency.
Indicates the relationship between In FIG. 5, line 11 represents a frozen road surface, line 12 represents a snow-packed road 1f11, and lines 13 and 14 represent a dry road surface. Also, in FIG. 6, line 15. /6 represents the warm road surface, and lines 17 and 7 to 8 represent the t-layer warm road surface. It can be seen from FIGS. 5 and 6 that there is a large correlation between the ratio H/V and the nodal shape I.

After determining the ratio H/V in step n4, the process moves to step n5 to determine the gradient of change Sk in the ratio H/V.

Figure 7 shows that in roadway 2 paved with asphalt,
It shows the time course of the degree of polarization γ when the first instar i continues to descend at time ti. This 7th thing!
[When descending from IIV, bias ・tsut
It can be seen that the degree γ has a constant change slope, and the difference in the ratio H/V over time is positive.

Figure 8 shows that on a road surface 2 covered with asphalt, at 1 time t2 a mountain or a small hill descends and becomes a small mountain.
It shows the change in the degree of polarization γ when it completely stops at time t3 and the Omukai light is irradiated by Q.

After becoming a rice field or a small mountain (Sai, 1j+n former J length γ
It can be seen that as time 1ijj N tTij decreases with a negative gradient.

After the slope of change Sk of the ratio H/V has been determined in step n5, the process moves to step n6, where it is determined whether or not the slope of change Sk is positive. When the change gradient Sk is positive, the process moves to step n7, where it is determined whether the ratio a/V satisfies the second equation.

α2<Kj<α3 (2) For example, α2. α3 is α2=:3 from FIGS. 5 and 6.
4, α3 = 8.6 is chosen. In this way, the gradient of change Sk is positive, and the ratio H/V changes the second equation to '6'l
Step n8 indicates that the road surface or mountain has begun to fall. Rain 1. : At the beginning of rain, the friction coefficient of the road surface decreases against the load, and by identifying the beginning of rain, it is possible to prevent danger when driving on road surfaces. Helpful.

ratio)(/V change slope Sk or stop, and the second equation is 1
If both are not produced, the process moves to step n9, and when the ratio H/V is 1 ``('' technique conversion Rk is calculated.Is the 2゛ conversion gradient IJms, k of the ratio H/V to be negative or negative? When it is determined, in step nlO, the rate of change of 1)-i,l is calculated when the ratio H/V is 1).

FIG. 9 shows the ratio when running on a 1) surface 2 covered with asphalt.

Line 19 covers the dry road surface, line e1() covers the wet road surface, and line 7711 shows the ratio H/V unchanged over time when driving on the snow-melting road 1 river for the time W1. As is clear from Figure 0 and 9, the rate of change Rk of the ratio H/V in the Tosojiro area is larger than that of dry mackerel (and wet 1i > +++1).

In step nil, it is determined whether the time rate of change Rk of the ratio H/V exceeds a predetermined threshold [αR1]. For example, Rl=3. When LtJH/'V, 1ijl change Li Rk meets threshold value R1,
Proceeding to step n12, it is determined that the road surface is melting snow. When the ratio H/V th1 change k is less than the threshold fmR1, move to step n13;
It is determined whether the ratio H/V exceeds a predetermined value α2. When the ratio H/V exceeds α2, step n14
Next, it is determined whether the outside air temperature T detected by the outside air temperature good detector 27 is less than a predetermined temperature T1.

As shown in Table 2, it can be seen that the mirror-like frozen road surface has polarization characteristics comparable to that of the wet road mJ.

Table 2 Therefore, in this IJJ, frozen road surface and wet road [71+
In order to determine this, not only the 1 ratio H/V but also the outside air temperature T is used as a parameter. When the outside temperature MT is equal to the predetermined temperature TI, it is determined in step n15 that the road 101 is frozen; otherwise, step n17. At n18, it is determined that the road surface is wet or slightly wet. For example, T1 is set at +5°C.

In step n14, the outside air temperature T is set to a predetermined temperature i.
When it is T1 or more, the process moves to step n16 and the ratio H
It is determined whether /v exceeds a predetermined value α3, and α
If it exceeds 3, it is determined in step n17 that the road surface is wet. In step n16, if it is determined that the ratio H/V is less than or equal to α3, the process moves to step n18, where it is determined that the road surface is slightly flat, for example, the rain is starting to rain or is stopping. .

In step n13, the ratio H/V is set to a predetermined value α2.
If it is below, step n13 to step n1
9, it is determined whether this ratio H/V exceeds a predetermined value α1. When the ratio H/V exceeds the predetermined value αl and is less than or equal to the predetermined value α2, it is determined in step n20 that the road surface is in a dry state. For example, α1 = 1.4.

When the ratio H/V is less than or equal to the predetermined value α1, it is determined in step n21 whether the roadway (2) is covered with compacted snow or frozen.

The operation for determining the road surface condition shown in FIG. 3 is as follows:
The ratios H/v, Rk, Sk shown in Table 3.

This is done using the parameters of T. ○ in Table 3
The marks indicate parameters used to determine the road surface condition.

Table 3 In the above-mentioned embodiment, the threshold values αl to α3. Although R1, T1, etc. have been set, according to the experiment of the present invention, these threshold values may be set as appropriate depending on changes in the road surface condition.

FIG. 10 shows a situation in which the threshold value changes with hysteresis as the state of the path r+n2 changes. 101ffl(1) indicates the threshold values α1 to α3 of the ratio H/V, and the subscript a indicates the condition when the road surface 2 in FIG. 10(1) changes from the right to the left in FIG. 10(1). is the threshold value, and the subscript is road surface 2 or 1.
0 shows the value when changing from left to right in Figure (1). FIG. 10 (2) shows the threshold values R1a and R1b of the time rate of change Rk of the ratio H/V, and FIG. 10 (3) shows the threshold value 5l-84 of the change slope Sk of the ratio H/V. , Figure 10 (
4) shows the threshold values Tla and Tlb of the outside air 'yA degree T.

According to the present invention, as shown in FIG. 10, the threshold 1. M may be changed.

As described above, according to the present invention, the light receiving device receives the reflected light of the light irradiated onto the path (2) from the older optical device, and the horizontally polarized component or the vertically polarized component of the reflected light out of the 1j power from the light receiving device. Since the level of one of these components is discriminated based on a predetermined level, and the discrimination operation is performed only when one of the components is equal to or higher than the above-mentioned level, erroneous detection of the road surface condition is eliminated.

[Brief explanation of drawings]

FIG. 1 is a simplified diagram of a 1 + IM example of the present invention; FIG. 2 is an overall block diagram of an embodiment of the present invention; and FIG. 3 is a diagram of the processing circuit 23 shown in FIG. 2. A flowchart for explaining the operation, Figure 4 is a diagram showing the S/N ratio of horizontally polarized light output and vertically polarized light output corresponding to the road surface condition, and Figures 5 and 6 are the ratio H/V corresponding to the road surface condition. Figure 7 is a graph showing the temporal change in the degree of polarization γ when it starts to rain, Figure 8 is the degree of polarization from when the rain becomes light until it stops completely. The graph shown in Fig. 9 shows no deterioration of γ over time, and the ratio H/V is 1tJjt?
Figure 10, a graph for explaining the +J change rate, is a diagram showing a threshold 101 that should be set in response to changes in road surface conditions. l... Light emitting device, 2... Road surface, 3... Light receiving device ↑W
z 5... Light emitting diode, 6... Condensing lens, 7
...Image portion νJll lens, 8...Horizontal polarizer, 9.
...Vertical polarizer, 10°11... Light receiving element, 14.1
5...Amplification circuit, 16°17...Filter, 18.
19... Aftermath rectification/smoothing circuit, 22... Analog/
Digital converter, 23... Processing circuit, 24.29...
・Comparison circuit, 27... Outside air temperature detector, 32... Control/display device agent Patent attorney Kei Nishi Part Figure 5 σ1 Figure 6 Figure 7 Elapsed time (minutes) 2 t3 Figure 9 Progress HourFIFl (minutes)

Claims (1)

[Scope of Claims] A light-emitting device that irradiates unpolarized light onto a road surface; a light-receiving device that receives reflected light from the road surface; The level of one of the polarized light components is discriminated at a predetermined level, and the road surface condition is determined based on at least one of the horizontal polarized light component and the vertical polarized light component only when any one of the polarized light components is equal to or higher than the IF level. A road surface condition determination device comprising: means.