KR100510117B1 - Vehicle detecting Apparatus and method for checking error operation due to external light - Google Patents

Abstract

The present invention relates to a vehicle detection apparatus that can accurately classify vehicle types even in an environment with external interference such as sunlight, and receives an optical signal incident from the outside, converts the electrical signal into an electrical signal, and then detects a DC level of the received signal. A light receiving unit; A comparator for comparing the detected DC level with a reference DC level; And a control unit which determines that the received signal is valid data if the detected DC level is less than the reference DC level, and otherwise determines that the received signal is invalid data so that vehicle detection to vehicle type determination can be more accurately controlled. Can be.

Description

Vehicle detecting apparatus and method for preventing malfunction due to external light {Vehicle detecting Apparatus and method for checking error operation due to external light}

The present invention relates to a vehicle detection apparatus for detecting whether a vehicle passes, and more particularly, to a vehicle detection apparatus capable of accurately classifying vehicle types even in an environment with external interference such as sunlight.

The vehicle detecting device is an automatic or unmanned device related to toll collection on a toll road. The sensor unit is installed on both sides of the road and a plurality of outgoing / receiving photoelectric sensors are arranged at regular intervals on and off according to the passage of the vehicle. Detect whether the vehicle has passed by detecting the state. However, since the device for detecting whether the vehicle passes is installed outdoors, the light sensor may be affected by data detection according to the intensity of sunlight or other external light. In particular, in a situation where the light receiving sensor receives direct sunlight, there is a problem that an error occurs in the determination result according to light transmission and reception of the light emitting unit and the light receiving unit.

The technical problem to be achieved by the present invention is to provide a vehicle detection apparatus and method that can accurately detect vehicle information by preventing malfunction due to interference of sunlight.

According to an aspect of the present invention, there is provided a vehicle detecting apparatus comprising: a light receiving unit configured to receive an optical signal incident from an outside, convert the light signal into an electrical signal, and then detect a DC level of the received signal; A comparator for comparing the detected DC level with a reference DC level; And a control unit that determines that the received signal is valid data if the detected DC level is less than the reference DC level, and otherwise determines the received signal as invalid data.

The vehicle detection method according to the present invention for achieving the above technical problem, in the method for detecting whether the vehicle passes by using the light emitting unit and the light receiving unit of the vehicle detection device, the reference DC level for the normal operation of the light receiving unit Determining and storing it; Emitting an optical signal from the light emitting unit and then detecting the optical signal at the light receiving unit corresponding thereto; Detecting a DC level of the received signal detected by the light receiving unit to determine whether the detected DC level is smaller than the reference DC level; And a control unit that determines that the received signal is valid data if the detected DC level is less than the reference DC level, and otherwise determines the received signal as invalid data.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 shows an example of a sensor unit of a vehicle detection apparatus according to the present invention. The sensor unit receives the light-receiving unit-emission in the vertical downward direction in correspondence with the light-emitting unit and the light-receiving unit of the A-type sensor unit 11 and the A-type sensor unit 11 which are arranged in order in the vertically downward light-emitting unit-receiving unit. It consists of the B-type sensor unit 13 arranged in order in the order of the negative. Thus, the light emitting portion of the A-type sensor portion 11 and the light receiving portion of the B-type sensor portion 13 form one optical axis or the light emitting portion of the B-type sensor portion 13 and the A-type sensor portion ( The light receiving portion of 11) forms one optical axis. Typically, four pairs of light emitting portion-light receiving portions are mounted on one board. Therefore, in the example of FIG. 1, each sensor part 11 or 13 is comprised by eight boards of 32 pairs of light emitting part-light receiving parts.

A method of detecting whether a vehicle passes through a detection space formed between the A-type sensor section 11 and the B-type sensor section 13 will be described. In order to determine whether the light is transmitted and received in each optical axis unit, the light emitter transmits the light sequentially in a sequential time. For example, while transmitting light (T1) from the lowest light emitting part of the A-type sensor part 11 to the lowest light receiving part of the B-type sensor part 13 at the first optical axis, the 34th optical axis ( The light is transmitted from the light emitting part of the B-type sensor part 13 to the light receiving part of the A-type sensor part 11 at an optical axis near the middle of the entire optical axes (R1). Next, the optical transmission / reception inspection is performed by the third optical axis T2 and the 36th optical axis R2, and as shown in FIG. 1, T3 / R3 (the fifth optical axis and the 38th optical axis), and T4. Optical transmission / reception inspection is performed in the order of / R4 (optical axis 7 and optical axis 40). The time required to scan all the optical axes is usually within 1 second, and it is possible to adjust the scanning time in the optical axis unit quickly or late in consideration of the traveling speed of the vehicle.

Whether the vehicle passes through the detection space is determined whether the light emitted from the light emitting portion of the A-type sensor portion 11 is received by the light receiving portion of the B-type sensor portion 13 corresponding thereto, and the B-type sensor portion ( The light emitted from the light emitting portion 13 is detected according to whether the light receiving portion of the A-type sensor portion 11 corresponding thereto is received. If the light emitted from the light emitting unit of the A-type sensor unit 11 is not received by the light receiving unit of the B-type sensor unit 13 or the light emitted from the light emitting unit of the B-type sensor unit 13 is A If there is at least one state that is not received by the light receiving portion of the type sensor unit 11, it is recognized that the vehicle passes between the detection spaces.

2 is a block diagram illustrating a vehicle detection apparatus according to the present invention. The light emitter 21 emits a predetermined infrared signal, and the light receiver 25 receives the infrared light 22 from the light emitter 21 together with the sunlight 23 from the sun.

The light receiving unit 25 includes a light receiving transistor 251 for converting an optical signal incident from the outside into an electrical signal S, an analog-digital converter 252 for converting an analog electrical signal into a digital signal, and a DC level of a received signal. A comparator 253 for comparing with the DC level Dmax and a controller 254 for determining vehicle type discrimination based on the comparison result.

3 is a diagram illustrating an output signal S of the light receiving transistor 251. The output signal includes a DC level (Do) determined by the DC bias circuit to the transistor, a DC level (d) represented by irradiation of sunlight, and an infrared (IR) signal transmitted from the light emitting unit.

4 is a view for explaining a method of removing the interference of sunlight in the vehicle detection apparatus according to the present invention. First, the light receiver 25 experimentally determines a maximum DC level Dmax for a normal operation. When the light receiving transistor 251 is biased at a DC range of a predetermined range, the light receiving transistor 251 may be linearly recognized in proportion to the received IR signal, but when biased at a DC level exceeding the predetermined range, the transistor is saturated and the amplitude of the infrared signal is distorted. This will not be recognized properly. The maximum value of the DC level at which the normal operation is possible is called the maximum DC level Dmax, and varies depending on the characteristics of the light receiving transistor used in the light receiving unit 25. Accordingly, the DC level of the light-receiving transistor 251 used is operated while varying the DC level, thereby obtaining a DC level at which the amplitude of the infrared signal is abnormally distorted. The DC level experimentally obtained in step 41 is stored in the memory.

In order to detect whether the vehicle passes by using the light emitting unit and the light receiving unit of the vehicle detecting apparatus, the light emitting unit emits an optical signal and the corresponding light receiving unit detects the optical signal (42). The DC level of the light receiving signal detected by the light receiving transistor of the light receiving unit is detected (43), and it is determined whether the detected DC level is smaller than the maximum DC level (44).

If the detected DC level is less than the maximum DC level, it is determined that the currently detected data is valid data (45), and the valid data is used for classifying the vehicle. That is, based on the amplitude (magnitude) of the AC signal detected at this time, it is judged whether or not the infrared signal emitted from the light emitting portion at the optical axis has been received. On the other hand, if the detected DC level is greater than the maximum DC level, the currently detected data is determined as invalid data (47), and the data is not used for classifying the vehicle. The above process is repeated until the inspection of all optical axes is completed (48).

The invention can also be embodied as computer readable code on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like, which are also implemented in the form of a carrier wave (for example, transmission over the Internet). It also includes. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

The best embodiments have been disclosed in the drawings and specification above. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, according to the vehicle detection apparatus according to the present invention, in consideration of the electrical characteristics of the light-receiving transistor in the light-receiving unit, an appropriate DC level at which the light-receiving transistor can operate normally is set in advance, and the light-receiving signal is set based on the reference value. By analyzing, the optical signal input in the abnormal environment can be removed from the vehicle detection determination object. Therefore, vehicle detection to vehicle model discrimination can be controlled more accurately.

1 shows an example of a sensor unit of a vehicle detection apparatus according to the present invention.

2 is a block diagram illustrating a vehicle detection apparatus according to the present invention.

3 is a diagram illustrating an output signal S of the light receiving transistor 251.

4 is a view for explaining a method of removing the interference of sunlight in the vehicle detection apparatus according to the present invention.

Claims (2)

A light receiving unit which receives an optical signal incident from the outside to detect a DC level of the received signal; A comparison unit for comparing the detected DC level with a reference DC level set to a maximum value of a DC level at which the light receiving unit can operate normally; And And a control unit for determining that the received signal is valid data if the detected DC level is less than the reference DC level, and otherwise determining the received signal as invalid data. In the method for detecting whether the vehicle passes, etc. using the light emitting portion and the light receiving portion of the vehicle detection device,  Determining a reference DC level as a maximum value of a DC level at which the light receiving unit can normally operate and storing the same; Emitting an optical signal from the light emitting unit and then detecting the optical signal at the light receiving unit corresponding thereto; Detecting a DC level of the received signal detected by the light receiving unit to determine whether the detected DC level is smaller than the reference DC level; And And a control unit for determining that the received signal is valid data if the detected DC level is less than the reference DC level, and otherwise determining the received signal as invalid data.