JPH1039024A - Sensor for presence/absence of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the possibility of incorrect determination and to enable the accurate determination of presence or absence by providing a determining means which determines whether a vehicle is present or absent at a location to be determined according to the calculated results of a distance calculating means and level calculating means. SOLUTION: A level calculating part 31 is fed the amplitude information of the signal of light reception which is extracted by a rectifying circuit 17 by rectifying the signal of light reception and an AGC signal which is generated by a AGC circuit 16 on the basis of the information. A calculating part 31 calculates the level of light reception from the inputs of the circuit 17 and 16 and sends the results to a presence determining part 32. Here the calculated distance value sent from a low pass filter 18 and the calculated level value sent from the calculating part 31 are compared with a floor distance value and floor level value stored in advance in a floor distance storage part 21 and floor level storage part 33 respectively. By their differences, it is possible to determine whether a parking vehicle is present or not at a location to be determined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vehicle presence / absence sensor device for determining the presence / absence of a vehicle upon entry into a parking lot or the like.

[0002]

2. Description of the Related Art Conventionally, there has been used a vehicle presence / absence sensor which is mounted on an indoor ceiling in a parking lot or the like and detects the presence / absence of a parked vehicle by the reflection of a projected wave. This type of vehicle presence / absence sensor determines the presence / absence of a vehicle based on the difference between the distance to the floor set at the time of installation and the distance calculated from the reflected wave, and the configuration is as shown in FIG. I have.

In FIG. 1, reference numeral 11 denotes a signal generator for generating a reference sine wave signal. The sine wave signal generated by the signal generator 11 is intensity-modulated by a light projecting unit 12 to determine a lower part of the apparatus. The light is emitted toward the target position, and is also sent to the multiplication circuit 13.

[0004] However, the irradiation light reflected at the determination target position is received by the light receiving section 14, and the narrow band amplifier 15 amplifies only the same frequency band component as the irradiation light by the light projecting section 12.

The amplification factor of the narrow band amplifier 15 is AGC
The amplitude of the signal is variably adjusted by the AGC signal from the circuit 16 so that the amplitude of the signal becomes constant. The light receiving signal having the specific frequency component amplified through the narrow band amplifier 15 is sent to the multiplication circuit 13 and the rectification circuit 17. .

The rectifier circuit 17 rectifies the received light signal and extracts the amplitude information of the received light signal and supplies it to the AGC circuit 16. The AGC circuit 16 narrows the band based on the amplitude information from the rectifier circuit 17. By supplying the AGC signal to the amplifier 15, the narrow-band amplifier 15 adjusts the amplitude of the received light signal to be constant as described above.

The multiplying circuit 13 multiplies the received light signal whose amplitude has been adjusted to a constant value by a reference sine wave signal, and removes a high-frequency component from the product signal by a low-pass filter 18 so as to reciprocate to the object. A transfer difference signal corresponding to the distance can be obtained.

[0008] A distance value to the object is calculated by subjecting the phase difference signal to arithmetic processing in the distance calculating section 19. The calculated distance value is sent to the presence / absence determination unit 20, and the presence / absence determination unit 2
At 0, the presence or absence of a parked vehicle at the determination target position is determined based on the difference between this distance value and the floor distance stored in advance in the floor distance storage unit 21, and the determination result is sent to an external display device or the like (not shown). Output.

In the above configuration, the distance calculation unit 1
9 calculates the distance value from the phase difference signal to the object by the following equation: D = (C / f) × (Δθ / 360 °) × (1/2) (1) (where D: Distance to the object (calculated distance), C: speed of light (= approximately 2.998 × 10 ⁸ [m / s]) f: irradiation light frequency, Δθ: phase difference calculated from the phase difference signal. It is.

On the other hand, the presence / absence judgment unit 20 calculates the calculated distance D obtained in this manner and the floor distance D0 stored in the floor distance storage unit 21 from the time of installation of the apparatus as shown in the flowchart of FIG. Whether or not “D0−D ≧ k” is satisfied, that is, whether or not the difference between the floor distance D0 and the calculated distance D is equal to or greater than a predetermined value k (step A1), determines whether or not there is a parked vehicle at the determination target position. (Steps A2, A
3) The result of the determination is externally output (step A4). Note that the constant value k is determined in consideration of the installation position (height) of the light projecting unit 12 and the light receiving unit 14 and the height of the vehicle to be determined.

[0011]

However, in the above-described apparatus, when the difference between the calculated distance D and the floor distance D0 is equal to or greater than a certain value k, it is determined that there is a parked vehicle. Therefore, for example, when the irradiation light from the light projecting unit 12 is applied to the front, rear, and side glass parts of the entering vehicle, the amount of light reflected to the light receiving unit 14 is greatly reduced. Since the light receiving level in the light receiving unit 14 is out of the dynamic range of the apparatus, that is, the level calculation error falls outside a predetermined range, and the error of the calculated distance D increases, the probability of erroneous determination is extremely high. Become.

Normally, the beam width of the irradiation light of this type of apparatus is as narrow as several degrees, and the irradiation light is applied to the glass part of the vehicle as described above from the relationship between the mounting position of the apparatus and the storage position of the vehicle. Irradiation is not a rare event, and it is not always possible to accurately determine the presence or absence of a vehicle.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the probability of erroneous determination as much as possible and to always accurately determine the presence or absence of a vehicle. An object of the present invention is to provide a non-sensor device.

[0014]

According to the first aspect of the present invention,
A light projecting means for irradiating an optical signal to a target position for determining the presence or absence of a vehicle, a light receiving means for receiving reflection of the optical signal from the target position by the light projecting means, and a light receiving signal obtained by the light receiving means Distance calculating means for calculating a distance from the light projecting means to the target position based on a phase difference from an optical signal emitted by the light projecting means, and level calculating means for calculating a signal level of a light receiving signal obtained by the light receiving means And determining means for determining the presence or absence of the vehicle at the target position according to the calculation results of the distance calculating means and the level calculating means.

[0015] With this configuration, it is possible to determine whether or not the vehicle is present not only when the signal level of the light receiving signal is within the dynamic range of the apparatus but also when the signal level is out of the dynamic range. This can be performed accurately, and the probability of erroneous determination can be reduced.

According to a second aspect of the present invention, in the first aspect of the present invention, the determination means is configured to determine the object even when the calculation results of the distance calculation means and the level calculation means do not continuously change from the same range. It is characterized in that the presence or absence of a vehicle at a position is determined.

With such a configuration, in addition to the operation of the first aspect of the present invention, when the signal level of the received light signal falls within the dynamic range of the apparatus or when the signal level deviates from the dynamic range. Since the determination of the presence or absence of the vehicle is performed in consideration of each time, the determination can be performed more accurately, and the probability of erroneous determination can be further reduced.

[0018]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the circuit configuration, which is basically the same as that shown in FIG. 4 above. Therefore, the same portions are denoted by the same reference numerals and description thereof will be omitted.

However, the rectification circuit 17 rectifies the light reception signal and extracts the amplitude information of the light reception signal and the AGC circuit 16
And an AGC signal created based on the amplitude information are supplied to the level calculator 31.

The level calculator 31 calculates the light receiving level based on the input from the rectifier circuit 17 and the AGC circuit 16, and sends the calculation result to the presence / absence determining unit 32. The presence / absence determination unit 32 stores the calculated distance value sent from the low-pass filter 18 and the calculated level value sent from the level calculation unit 31 in the floor distance storage unit 21 and the floor level storage unit 33, respectively, in advance. It compares the determined floor distance value and floor level value, determines the presence or absence of the parked vehicle at the determination target position based on the difference, and outputs the determination result to an external display device or the like (not shown).

In the above configuration, the multiplication circuit 13
The phase difference signal corresponding to the reciprocating distance to the object, which is obtained by removing the high-frequency component from the product signal in the low-pass filter 18, can be represented by Acos θ where the level of the light receiving signal in the light receiving unit 14 is A. The distance calculation unit 19 calculates the Ac from the phase difference signal using the above-described equation (1).
The phase difference θ is calculated from os θ and sent to the presence / absence determination unit 32.

On the other hand, the level calculating section 31 determines the light receiving level A based on the amplitude information from the rectifier circuit 17 and the AGC signal from the AGC circuit 16 based on the following equation: A = (amplitude) / (AGC) (2) The calculated light receiving level value A is sent to the presence / absence determining unit 32.

The presence / absence determination unit 32 determines whether or not there is a parked vehicle at the determination target position in accordance with the processing procedure shown in FIG. That is, first, the light receiving level value A from the level calculating section 31 and two threshold values A1 and A2 (A1 <A2) set in advance for this device are "A≤A1" or "A2≤ A ”, it is determined whether the presence / absence determination based on the calculated distance D is possible (step B).
1). The method of setting the two thresholds A1 and A2 will be described later.

If it is determined in step B1 that "A≤A1" or "A2≤A", that is, if it is determined that the presence / absence determination based on the calculated distance D is impossible, the position to be determined is determined. It is determined that the reflectance of the object to be measured has changed due to the entry of the vehicle, and that the light receiving level value A has changed. Then, it is determined whether or not this state continues for a predetermined time Δt, for example, 3 [sec] or more. (Step B
4).

If it is determined in step B1 that neither "A≤A1" nor "A2≤A" is satisfied and the presence / absence determination based on the calculated distance D is possible, the distance calculator 19 determines The calculation “D0−D” is performed using the calculated distance D obtained and the floor distance D0 stored in the floor distance storage unit 21 since the apparatus was installed.
.Gtoreq.k ", that is, whether or not the difference between the floor distance D0 and the calculated distance D is equal to or greater than a predetermined value k (step B2). This constant value k is determined in consideration of the installation positions (heights) of the light projecting unit 12 and the light receiving unit 14 and the height of the vehicle to be determined.

Then, in step B2, "D0 -D≥
Even if it is determined that “k” is reached, it is then determined whether or not this state continues for a preset time Δt, for example, 3 seconds or more (step B4).

However, in this step B4, "A≤A1
"A2≤A" or "D0 -D≥
If it is determined that the state of “k” has continued for the preset time Δt or more, it is determined that there is a parked vehicle at the determination target position (step B5).

In step B4, if the state of "A≤A1" or "A2≤A" or the state of "D0-D≥k" changes without continuing for a predetermined time Δt or more. In step B2, "D0 -D≥
If it is determined that the vehicle is not in the state of "k", it is determined that there is no parked vehicle at the determination target position (step B3).

Then, the judgment result in the step B3 or B5 is output to the outside (step B6).
Thus, the processing by the presence / absence determination unit 32 ends. A method for setting the two thresholds A1 and A2 will be described below with reference to FIG. That is, for example, in an apparatus having a distance calculation error characteristic as shown in FIG.
D0 is the floor distance calculation error, and g is the floor distance calculation error ΔD0.
If A0 is the floor level, the calculation error allowed from
The two threshold values A1 and A2 are set at the time of installation of the apparatus, and the error relative value of the calculated distance is a predetermined ± g with respect to the distance D calculated using the floor level A0 stored in the floor level storage unit 33. The lower limit value and the upper limit value of the light receiving level value A within the range.

Therefore, when the light receiving level value A calculated by the level calculating section 31 is within the range of the threshold values A 1 and A 2, the presence or absence of the vehicle is determined by calculating the distance D by the distance calculating section 19. If it is determined that the threshold value is outside the range of the threshold values A1 and A2, the light receiving level is changed because the light emitted from the light emitting unit 12 is applied to, for example, a glass part of the vehicle. It is determined that the vehicle is parked and that the vehicle is parked.

Further, before determining that the vehicle is in the parking lot, a process of confirming that the state has continued for a predetermined time Δt or more is performed, so that the determination of the presence or absence of the vehicle can be performed more easily. It can be stable and accurate.

[0032]

According to the first aspect of the present invention, the presence or absence of the vehicle is detected not only when the signal level of the received light signal is within the dynamic range of the apparatus but also when the signal level is out of the dynamic range. Can be accurately determined, and the probability of erroneous determination can be reduced.

According to the second aspect of the present invention, in addition to the effect of the first aspect of the present invention, when the signal level of the received light signal falls within the dynamic range of the apparatus or deviates from the dynamic range. Therefore, the determination of the presence or absence of the vehicle is performed in consideration of the time, so that the determination can be performed more accurately, and the probability of erroneous determination can be further reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration according to an embodiment of the present invention.

FIG. 2 is a flowchart mainly illustrating processing of a presence / absence determination unit according to the embodiment;

FIG. 3 is a view exemplifying a distance calculation error characteristic according to the embodiment;

FIG. 4 is a block diagram showing a circuit configuration of a conventional vehicle presence / absence sensor device.

FIG. 5 is a flowchart illustrating a process of a presence / absence determination unit in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Signal generator 12 ... Light emitting part 13 ... Multiplier circuit 14 ... Light receiving part 15 ... Narrow band amplifier 16 ... AGC circuit 17 ... Rectifier circuit 18 ... Low pass filter 19 ... Distance calculating part 20 ... Presence / absence determining part 21 ... Floor distance Storage unit 31: Level calculation unit 32: Presence / absence determination unit 33: Floor level storage unit

Claims (2)

[Claims] 1. A light projecting means for irradiating an optical signal to a target position for determining the presence or absence of a vehicle, a light receiving means for receiving reflection of an optical signal from the target position by the light projecting means, Distance calculating means for calculating a distance from the light projecting means to the target position based on a phase difference between the obtained light receiving signal and the light signal emitted by the light projecting means; and a signal level of the light receiving signal obtained by the light receiving means. A vehicle presence / absence sensor device comprising: a level calculation means for calculating; and a determination means for determining presence / absence of a vehicle at the target position according to calculation results of the distance calculation means and the level calculation means. 2. The method according to claim 1, wherein the determining unit determines whether the vehicle is present at the target position based on a time during which the calculation results of the distance calculation unit and the level calculation unit do not continuously change from the same range. Item 4. The vehicle presence / absence sensor device according to Item 1.