JP2852844B2 - Vehicle Sensing Method by Following Road Reflection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle sensing method for following road surface reflection for collecting road traffic information.

[0002]

2. Description of the Related Art Conventionally, in order to collect road traffic information, a light emitter is attached to a brace extending in the direction of a road from a pillar built on the side of a road, and a light beam such as infrared rays is transmitted from the light emitter to a road surface. A method of detecting the number of passing vehicles by detecting the amount of light reflected from a road surface has been adopted.

[0003] In this case, the time average value of the reflected light is considered as the reflection from the road surface, and it is determined that the vehicle is sensed when the difference between the reflected light and the reflected light from the vehicle is detected to a certain degree or more. As another method, a reflection level from a road surface is set to a fixed value, and a signal having a level higher than that by a predetermined amount or more is detected as a vehicle.

[0004]

However, in such a conventional method, the reflection level of the road surface changes due to weather changes such as rain and cannot be kept constant, and a change in transmittance due to contamination of the light receiver occurs. , Because the reflection level gradually decreases,
The method of setting the road surface reflection to a fixed value has a problem that it does not conform to the actual situation.

[0005] The method of using the average value of the reflection level of the road surface and the vehicle as the reflection level of the road surface solves the problem of the level change due to aging or the like. There has been a problem that the light quantity becomes a value far from the measured value.

The present invention has been made in view of such circumstances, and is intended to correctly detect road surface reflection even when traffic jams or the like occur.

[0007]

In order to solve such a problem, the present invention relates to a main beam transmitted to a road surface.
The first sensor detects the amount of reflected light of
Out of the road reflection detection point
The reflected light amount of the sub-beam is sensed by the second sensor,
The rising waveform of the amount of reflected light obtained from the second sensor
Predicts the vehicle speed of the traveling vehicle based on
Judgment of the presence of both vehicles, the first time when it is judged that there is no preceding vehicle
The amount of reflected light obtained by the detector
Judged as the amount of road surface reflection from the surface and determined from the amount of road surface reflection
When a higher amount of reflected light is obtained by the first sensor ,
It is determined that the amount of light is reflected from the vehicle .

[0008]

The reflected light of the sub-beam obtained from the second sensor
Predicts the speed of the traveling vehicle based on the rising waveform of the amount
And the presence of a preceding vehicle is determined, and it is determined that there is no preceding vehicle.
The main beam obtained by the first sensor
The amount of reflected light that is higher than the amount of road surface reflected by a predetermined amount
If it is obtained by the
Refused.

[0009]

FIG. 1 is a view showing one embodiment of the present invention. As shown in FIG. 2, a sensor 1 is provided with a sensor control unit 10 on a pillar 5 provided on the road side, as shown in FIG. The sensor light emitting and receiving unit 11 attached to the arm 6 extending from the road to the road surface emits the main beam 2 immediately below, and the main beam detector 11a for detecting the reflected wave of the main beam 2 reflected from the road surface is provided. Have. In addition, the sensor 11 includes a sub-beam detector 11b that sends out the sub-beam 3 at a predetermined angle ahead of the main beam 2 in order to detect the head of the vehicle traveling a predetermined distance before the main beam 2. .

The sub beam 3 detects a vehicle 4 located a predetermined distance before the main beam 2, and the predetermined distance is set based on the following criteria.
When the vehicle 4 runs at a normal speed, that is, when the vehicle 4 travels in a very natural state without traffic congestion and without running at an extremely high speed, the distance between the vehicle 4 and the preceding vehicle is safe. Should be kept at a reasonable distance.

Therefore, the predetermined distance is set to a distance slightly longer than the inter-vehicle distance, and the sub beam 3
When the head of the main beam 2 is detected,
If the road surface reflection that can be regarded as being after passing through is detected, it should be possible to judge that the reflection is from the road surface instead of the vehicle.

Specifically, if there is no signal change in the main beam 2 before and after the time when the vehicle 4 is detected by the sub-beam 3, the vehicle is not detected due to traffic congestion at that time. It can be determined that it is detected.

Further, if a change occurs in the main beam within a predetermined time after the vehicle 4 is detected by the sub-beam 3, the detected value of the main beam is not treated as road surface reflection. This corresponds to the case where the vehicle that has passed through the sub-beam 3 passes through the main beam 2 at an extremely fast speed.
Normally, the main beam 2 and the sub beam 3 are separated from each other by about 3 to 10 meters. In such a case, if the traveling speed is too high, a measurement error may occur. Therefore, it is desirable that the road surface reflection at that time is not detected. .

FIG. 3 is a block diagram showing the internal configuration of the sensor control section 10 and the sensor light emitting / receiving section 11. The sensor control unit 10 includes a power supply circuit 10a, a road surface level reading circuit 10
b, comparison and judgment circuit 10c, processing circuit 10d, output circuit 1
0e.

The sensor light emitting / receiving section 11 comprises a main beam detector 11a, a sub beam detector 11b, a normal traveling vehicle detection determination circuit 11c, and a power supply circuit 11d.

Each of the main beam detector 11a and the sub beam detector 11b includes a light emission signal generation circuit 110, a drive circuit 111, a light emission element 112, a light reception element 113, a band amplification circuit 115, and a detection integration circuit 115.

The sub-beam, for example, will be described in the device configured as described above. When an infrared signal transmitted from the light emitting element 112 is reflected from the vehicle and detected by the light receiving element 113, a predetermined signal component is output from the band amplification circuit 114. Is extracted and the signal shown in FIG. 4A is output. This signal has a steep rising waveform as shown in the first half when the speed of the vehicle is high, and has a gentle rising waveform as shown in the second half when the speed of the vehicle is low.

When this signal is detected and integrated by the detection integration circuit 115, it becomes a signal having a waveform shown in FIG. That is, the envelope of the signal shown in FIG. 4A is obtained, and is supplied to the normal traveling vehicle detection determination circuit 11c, and the vehicle speed is determined. That is, the voltage V2 after t time from when the output signal of the detection and integration circuit shown in (b) exceeds the level 1 shown by the voltage V1.
It is determined whether or not level 2 has been exceeded.

Here, as described above, the reason why the vehicle speed is required is that if the vehicle speed is too slow, the preceding vehicle may be present at the position of the main beam. It can be considered that there is no preceding vehicle at the position, and the surface reflection at that time may be reliably determined to be from the road surface. Therefore, it is sufficient to determine whether the required vehicle speed is equal to or higher than a predetermined speed.

For this reason, in this example, it is determined that the vehicle speed is equal to or higher than the predetermined value in a state where the time from exceeding level 1 to exceeding level 2 is equal to or lower than the predetermined value. An output signal is sent. The sensor control unit 10 reads the signal from the main beam by the road surface level reading circuit 10b according to this signal, and compares it with the value stored so far by the comparison judgment circuit 10c. Processing circuit 10
d, output via the output circuit 10e.

[0021]

As described above, the present invention provides the second
Rise of reflected light amount of sub-beam obtained from sensor
The vehicle speed of the traveling vehicle is predicted based on the waveform and the
When the presence or absence of the preceding vehicle is determined, the first sense
From the amount of road reflected light from the main beam obtained by the detector
When the amount of reflected light higher than a certain level is obtained by the first sensor
Is determined to be the amount of light reflected from the vehicle , so that the reflection from the vehicle during traffic congestion can be distinguished from the road surface reflection, and the signal reflected from the road surface can be reliably detected. In addition, since the road surface reflection amount can be constantly updated as long as the vehicle is only passing by, there is an effect that various changes in the road surface reflectance can be followed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing an overall configuration of the present invention.

FIG. 3 is a block diagram illustrating an internal configuration of a sensor control unit and a sensor light emitting / receiving unit;

FIG. 4 is a waveform diagram of each part showing a waveform of each part.

[Explanation of symbols]

 2 Main beam 3 Sub beam 4 Vehicle 10 Sensor control unit 11 Sensor light emitting / receiving unit 11a Main beam sensor 11b Sub beam sensor

Continuation of front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) G01V 8/20 G08G 1/04

Claims (1)

(57) [Claims] 1. A method for detecting a vehicle by detecting a vehicle by detecting a change in the amount of reflected light from a road surface by a sensor, wherein the reflected light amount of a main beam transmitted to a road surface is determined by a first method.
Detected by the sensor, a predetermined distance from the point of reflection of road reflection by the main beam
The reflected light amount of the sub beam sent to the front is sent to the second sensor.
And the rising waveform of the amount of reflected light obtained from the second sensor
Predicts the vehicle speed of the traveling vehicle based on
Judgment of the presence and absence of both vehicles, obtained by the first sensor at the time of judging that there is no preceding vehicle
The amount of reflected light is the light reflected from the road surface by the main beam.
Determining the amount, high reflected light amount more than the predetermined amount from the road surface reflection light amount first sensor
Judgment is the amount of reflected light from the vehicle if obtained by
A method of detecting a vehicle by following a road surface reflection.