JP2006021558A - Monitoring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a monitoring system capable of informing properly a monitor or a driver etc. of existence of pedestrians and/or vehicles in the monitoring region or at a crossing upon sensing the pedestrians and vehicles certainly and accurately. <P>SOLUTION: A signal transmitting means to make signal transmission of a sensing medium and a receiving medium to receive the sensing medium are installed on one side of the monitoring region while a reflecting means to reflect the sensing medium is installed on the other side, and the sensing medium is transmitted at all times from the transmitting means to the reflecting means and received by the receiving means, followed by calculation of the reflecting position every time signal is received, and the reference reception signal based on the sensing medium reflected by the reflecting means is emitted either with the reception intensity held unchangedly or upon amplification, and the reception signal based on the sensing medium reflected by other than the reflecting means is emitted either with the reception intensity held unchangedly or upon attenuation, and when reference reception signals go out or are attenuated, sensing is made for existence of the object to be sensed in the monitoring region. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a monitoring system for detecting a person or a vehicle in a monitoring area or a level crossing.

  When a detection medium such as a laser beam, an ultrasonic wave, or a microwave is transmitted / received in the monitoring area to detect that a person or a vehicle has entered or exists in the monitoring area, and the detection medium is blocked by the person or the vehicle In addition, it is determined that a person or vehicle is present in the monitoring area.

  For example, a railroad crossing monitoring system is installed at a railroad crossing to detect this and notify a driver of an approaching railroad vehicle when a vehicle is stuck on a vehicle passage. Conventionally, in this type of level crossing monitoring system, a method of monitoring a monitoring area with a television camera, a CCD camera, or the like has been widely used (for example, see Patent Document 1). However, with this method, the lens section of the TV camera, CCD camera, etc. must be periodically wiped, maintenance work is required, and when the visibility is poor due to rain, snow, fog, etc. Sometimes it cannot be detected.

  There is also known a method of irradiating a monitoring region with laser light or ultrasonic waves (millimeter wave or the like) and detecting the reflection (Doppler wave) (for example, see Patent Document 2). However, even in this method, the sensitivity is lowered due to irregular reflection of laser light and ultrasonic waves due to rain, snow, misty snow, and the like.

Furthermore, the use of microwaves as a detection medium is also considered (see, for example, Patent Document 3). However, since microwaves are transmitted from transmitters with a certain spread, microwaves are transmitted and received with the transmitters and receivers facing each other, and when microwaves are blocked by people or vehicles, When the distance between the transmitter and the receiver is increased, unnecessary reflected waves reflected by the surrounding structure and the train passing through the railroad crossing are incident on the receiver and received from the transmitter. May cause interference with a straight wave for detection of interception that directly enters the device, lowering the direct wave reception signal, and even if the straight wave is not intercepted by a person or vehicle, it may output a shutoff signal by mistake There is also.
JP 2002-145072 A JP 2003-11824 A JP 2003-107150 A

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a monitoring system that reliably and accurately detects a person or a vehicle in a monitoring area or a level crossing and accurately notifies a monitoring person or a driver. And

In order to achieve the above object, the present invention provides the following.
(1) A transmission means for transmitting the detection medium and a reception means for receiving the detection medium are arranged on one side across the monitoring area, and a reflection means for reflecting the detection medium is arranged on the other side for transmission. The detection medium is constantly transmitted from the means toward the reflecting means, and received by the receiving means.
For each received signal, the reflection position is calculated, and for the reference received signal based on the detection medium reflected by the reflecting means, the received intensity is output as it is or amplified, and the detection reflected by other than the reflecting means is detected. The received signal based on the medium is output with the received intensity or attenuated,
A monitoring system for detecting the presence of an object to be detected in a monitoring area when a reference reception signal is interrupted or attenuated.
(2) A dummy signal indicating reflection by an object virtually existing at an arbitrary position between the transmission unit and the reflection unit is output when the reference reception signal is interrupted or attenuated ( 1) The monitoring system described.
(3) The monitoring system according to (2), wherein the dummy signal is amplified in the same manner as the reference received signal or attenuated in the same manner as the received signal based on the detection medium reflected by a means other than the reflecting means and output. .
(4) The detection medium is a rotating wave whose electric field distribution rotates in one of the clockwise or counterclockwise directions, or the electric field distribution is less than 90 ° with respect to a horizontal or vertical plane including the microwave traveling direction axis. Any one of the above (1) to (3), which is an inclined linear wave inclined at an angle, and the reflection means reflects the microwave incident on the reflection means an even number of times and sends it to the reception means. The monitoring system according to item.
(5) A transmission means for transmitting the detection medium and a reception means for receiving the detection medium are arranged on one side across the vehicle passage in the railroad crossing, and a reflection means for reflecting the detection medium is arranged on the other side. The transmission medium is always transmitted from the transmission means to the reflection means, and received by the reception means.
For each received signal, the reflection position is calculated, and for the reference received signal based on the detection medium reflected by the reflecting means, the received intensity is output as it is or amplified, and the detection reflected by other than the reflecting means is detected. The received signal based on the medium is output with the received intensity or attenuated,
When the reference reception signal is interrupted or attenuates even after the barrier fence is lowered, it is judged that there are people or vehicles on the vehicle passage in the railroad crossing, and a warning is issued to the railway vehicle approaching the railroad crossing Railroad crossing monitoring system.
(6) A dummy signal indicating reflection by an object virtually existing at an arbitrary position between the transmission unit and the reflection unit is output when the reference reception signal is interrupted or attenuated ( 5) The level crossing monitoring system described.
(7) The level crossing monitoring according to (6), wherein the dummy signal is amplified in the same manner as the reference reception signal or attenuated in the same manner as the reception signal based on the detection medium reflected by a means other than the reflection means. system.
(8) The detection medium is a rotating wave whose electric field distribution rotates in one of the clockwise or counterclockwise directions, or the electric field distribution is less than 90 ° with respect to a horizontal or vertical plane including the microwave traveling direction axis. Any one of the above (5) to (7), which is an inclined linear wave inclined at an angle, and the reflecting means reflects the microwave incident on the reflecting means an even number of times and sends it to the receiving means. The level crossing monitoring system described in the section.

  According to the present invention, it is possible to reliably and accurately detect that a person or a vehicle is present or passing between the transmission means and the reflection means of the detection medium, and the reliability of monitoring is increased. Will be able to operate safely. Furthermore, by using microwaves as a detection medium, the influence of weather such as rain, snow, and fog can be eliminated as much as possible, and people and vehicles can be detected more reliably and accurately. In particular, by using a rotating wave or an inclined linear wave among microwaves, unnecessary reflected waves reflected by other than the reflecting means can be effectively eliminated, and the reliability of detection is further increased.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In the present invention, the detection medium is not limited, and laser light, ultrasonic waves, and the like can be used. However, there is a possibility that the sensitivity may be reduced due to irregular reflection of laser light or ultrasonic waves due to rain, snow, drizzle, etc. Therefore, microwave is preferable. Among them, a rotating wave whose electric field distribution rotates in one of the clockwise direction or the counterclockwise direction, or an inclination in which the electric field distribution is inclined at an angle of less than 90 ° with respect to a horizontal or vertical plane including the traveling direction axis of the microwave. A straight wave is preferred. As will be described later, these rotating waves and inclined linear waves have the property of changing the rotation direction or the inclination direction at each reflection, and accurately distinguish between those reflected by the reflecting means and those reflected by other objects. This is particularly preferable because it can be performed. Therefore, here, an embodiment in the case of using a microwave rotation wave and an inclined linear wave will be described.

  FIG. 1 is a schematic diagram showing an example of a monitoring system according to the present invention, in which a microwave transmitter l and a microwave receiver 2 are arranged side by side on the other side with a monitoring region R in between. The reflector 3 is disposed oppositely. The microwave transmitter 1 and the microwave receiver 2 are unitized and can be configured to transmit and receive microwaves using a common antenna. In addition, a person, a vehicle, or the like (hereinafter referred to as “detected object A”) moves in the monitoring region R in the direction of the arrow in the figure.

  The microwave transmitter 1 emits a straight wave W1a whose electric field distribution matches the voltage application direction of the oscillation diode 4. At this time, the microwave transmitter 1 is shown in the lower diagram of FIG. Thus, the electric field distribution is emitted toward the reflector 3 in a state where the electric field distribution intersects the plane P including the traveling direction axis of the microwave M at an angle of less than 90 °. The intersection angle can be any angle except that it is completely parallel (0 °) or orthogonal (90 °) to the plane P, but 45 ° is most preferable. When the linear wave W1a emitted so as to intersect with the plane P is reflected by the reflector 3, the direction of the electric field distribution is 90 ° when the intersecting angle is 45 ° with respect to the microwave traveling direction axis. ° Has the property of rotating. Therefore, in the state of FIG. 1A, the linear wave W1a emitted from the microwave transmitter 1 is reflected by one reflecting surface of the reflector 3, so that the direction of the electric field distribution is rotated by 90 °. And then reflected by the other reflecting surface so that it is rotated again by 90 ° to become a linear wave W1a having an electric field distribution that matches the electric field distribution of the original linear wave W1a. Is incident on the vessel 2.

  On the other hand, the microwave receiver 2 makes the detection direction of the receiving diode 5 coincide with the voltage application direction of the oscillation diode 4 of the microwave transmitter 1, and emits from the microwave transmitter 1 in the incident wave. Only those having an electric field distribution parallel to the straight traveling wave W1a are detected.

  The reflector 3 is composed of a pair of mirrors arranged with an inclination of 45 ° with respect to the traveling direction axis of the microwave M of the microwave transmitter 1 and the microwave receiver 2. The microwave M emitted from the vessel 1 is reflected twice by the reflector 3 and enters the microwave receiver 2. Further, the reflector 3 is arranged so that the angle can be adjusted so that the microwave M is reflected twice and is incident on the microwave receiver 2. In addition, as the reflector 3, although not shown, a curved surface capable of reflecting the microwave M twice, a corner cube, or the like can be used.

  In such a configuration, the detected object A moves in the direction of the arrow in the figure, but when the detected object A shown in FIG. 1A does not pass, the linear wave W1a emitted from the microwave transmitter 1 is The light travels straight and is reflected by one surface of the reflector 3 and further reflected by the other reflecting surface, and then enters the microwave receiver 2. That is, the linear wave W1a emitted from the microwave transmitter 1 is reflected twice by the reflector 3 and received by the microwave receiver 2. At that time, the linear wave W1a emitted from the microwave transmitter 1 is rotated by 90 ° in the direction of the electric field distribution by the first reflection (W2a), and further rotated by 90 ° by the second reflection. The electric wave distribution becomes a linear wave directed in the same direction as the linear wave W1a emitted from the microwave transmitter 1 and enters the microwave receiver 2. Since the microwave receiver 2 is configured such that the detection direction of the reception diode 5 coincides with the linear wave W1a emitted from the microwave transmitter 1, the received signal from the incident linear wave W1a is calculated by the calculation unit. (Not shown).

  From this state, when the detected object A passes between the microwave transmitter 1 and the reflector 3 as shown in FIG. 1B, the linear wave W1a emitted from the microwave transmitter 1 is The light is reflected by the detected object A and enters the microwave receiver 2. At this time, since the linear wave W1a is reflected once, the microwave receiver 2 has a linear wave W3a whose electric field distribution is rotated by 90 ° from the linear wave W1a emitted from the microwave transmitter 1. Is incident. Therefore, the microwave receiver 2 does not detect this linear wave W3a, and no reception signal is output to the arithmetic unit.

  FIG. 2 shows a configuration in which the microwave emitted from the microwave transmitter 1 is replaced with a rotating wave. As shown in the drawing, the microwave transmitter 1 includes a polarization converter 23 for polarizing a linear wave W1 oscillated from the oscillation diode 4 into a rotating wave W2. For the polarization converter 23, a known device can be used, for example, a 90 ° phase difference plate made of a dielectric material is mounted in the waveguide. The 90 ° phase difference plate is adjusted in thickness and length in the axial direction of the waveguide in order to perform circular polarization more effectively. For the same purpose, it is formed in a planar shape narrowed toward the axis of the waveguide, or in a planar shape in which a concave portion is partially omitted along the axis of the waveguide. Also, instead of the 90 ° phase difference plate, a metal blade member of a predetermined length is attached to the inner wall of the waveguide, or a metal lump is attached to the inner wall of the waveguide, and the cross-sectional shape thereof is a part of the circumference. The polarization converter 23 can also be configured by using a circular shape lacking. Further, a polarization converter 23 can be formed by connecting a turn-style branch circuit to the waveguide. The polarization converter 23 is mounted in the waveguide so as to intersect the voltage application direction of the oscillation diode 4 at a predetermined angle (E1: 45 °, for example).

  On the other hand, the microwave receiver 2 has a receiving diode 5 whose detection direction coincides with the voltage application direction of the oscillation diode 4, and a polarization converter 32 for returning the incident rotating wave W2 to the linear wave W1. Prepare. The polarization converter 32 can be the same as the polarization converter 23 mounted on the microwave transmitter 1 and has the same inclination angle (E1) as that of the polarization converter 23 in the waveguide. Installed.

  In the above configuration, when the detected object A shown in FIG. 2A does not pass, the linear wave W1 oscillated from the oscillation diode 4 is rotated by the polarization converter 23 having an electric field distribution that rotates in one direction. Polarized into a wave W2 and emitted from the microwave transmitter 1, the rotational direction of the rotating wave W2 is reversed by the first reflection by the reflector 3 (W3) and reversed again by the second reflection. Eventually, it enters the microwave receiver 2 as a rotating wave W2 that rotates in the same direction as the rotating wave W2 emitted from the microwave transmitter 1. The incident rotating wave W2 is polarized into the linear wave W1 when passing through the polarization converter 32 in the microwave receiver 2, and reaches the receiving diode 5. Since the electric field distribution of the linear wave W1 coincides with the detection direction of the receiving diode 5, the reception signal is output from the microwave receiver 2 to the arithmetic unit.

  From this state, as shown in FIG. 2 (b), when the detected object A passes, the rotating wave W2 emitted from the microwave transmitter 1 is reflected once by the detected object A, and its rotational direction. Is inverted and then enters the microwave receiver 2. The incident rotating wave W3 is polarized into a linear wave W1 by the polarization converter 32. However, since the electric field distribution is orthogonal to the detection direction of the receiving diode 5, the received signal is not output to the arithmetic unit.

  In the above detection method, the reflection position of the microwave can be calculated based on the time from the transmission to the reception of the microwave, and the object A to be detected is shown in FIG. 1 (a) or 2 (a). When there is no gap between the microwave receiver 1 and the reflector 3, a signal indicating the position of the reflector 3 (hereinafter referred to as “reference received signal”) appears strongly at the same position as shown in FIG. .

  In addition, since the microwave is transmitted with a certain spread, actually, the microwave is reflected by the road surface of the road R and surrounding objects, and when the microwave is reflected an even number of times, the reflected wave enters the microwave detector 2. Sometimes. Such unnecessary reflected waves appear in accordance with their reflection positions as indicated by broken lines in FIG. If the reflection position is close to the microwave receiver 2, an unnecessary reflected wave (I) having a high reception intensity may appear, which may cause a malfunction.

  Therefore, the reference received signal reflected by the reflector 3 is preferably amplified and output with its received intensity, and is reflected by an even number of times by other objects and received by the microwave receiver 2. Is output with the received intensity unchanged or attenuated. By such signal processing, when the detected object A does not exist between the microwave transmitter 1 and the reflector 3, the reference received signal by the reflector 3 appears clearly, and the received signal by the unnecessary reflected wave is Virtually lost. Such signal processing can be easily realized by those skilled in the art using known amplification means.

  Then, the reference reception signal from the reflector 3 is always output, and when the reference reception signal is interrupted or attenuated, as shown in FIG. 1B or FIG. It determines with passing between the microwave transmitter 1 and the reflector 3. FIG. This determination can be performed reliably and accurately because the influence of unnecessary reflected waves is eliminated as described above.

  In addition, a dummy signal can be output for the purpose of preventing further malfunction. As shown in FIG. 4, the position of the dummy signal that is assumed to have been reflected by an object virtually existing at an arbitrary position between the microwave receiver 2 and the reflector 3 is received by the reflector 3 as a reference. Output when the signal is interrupted or attenuated. Since the dummy signal appears at a certain position when the reference reception signal is interrupted or attenuated, the detected object A can be detected more reliably by monitoring the appearance position of the dummy signal. become. This dummy signal may be attenuated in the same manner as the unnecessary reflected wave, or may be amplified in the same manner as the reference reception signal.

  In order to generate a dummy signal, for example, as shown in FIG. 5, a coaxial cable of a predetermined length may be connected to a waveguide connected to a microwave transmitter / receiver, or a reflective object may be attached to the tip of an antenna. . The microwave transmitted from the microwave transmitter / receiver of the microwave transmitter / receiver propagates through the coaxial cable and is reflected at the tip and returned to the microwave transmitter / receiver, or reflected by the reflecting object at the tip of the antenna and micro-transmitted. It returns to the wave transceiver and is received by the microwave receiver. Therefore, the appearance position of the dummy signal can be adjusted by the length of the coaxial cable and the attachment position of the reflecting object.

  The above monitoring system can be applied to a level crossing as it is. That is, the above-mentioned monitoring region R is regarded as a vehicle passage in a railroad crossing, the microwave transmitter 1 and the microwave receiver 2 are arranged on one side across the vehicle passage, and reflected on the other side. The body 3 is arranged to transmit / receive a microwave tilt wave or rotation wave. Similarly, the reference reception signal is always output, and when the reference reception signal is interrupted, a dummy signal is output as necessary to determine that a person or vehicle is passing the vehicle passage in the railroad crossing. When the reference reception signal is interrupted and it is determined that there are people or vehicles on the vehicle traffic path even after the barrier fence is lowered, an alarm is issued to the approaching train.

  In this way, the level crossing monitoring system also eliminates the effects of unwanted reflected waves, so it is possible to reliably and accurately detect people and vehicles passing through the vehicle passages within the level crossing, enabling safe train operation. Become.

It is a schematic block diagram which shows an example of the apparatus which constructs the level crossing monitoring system of this invention. It is a schematic block diagram which shows the other example of the apparatus which constructs the level crossing monitoring system of this invention. It is a figure which shows the example of a received signal. It is a figure for demonstrating a dummy signal. It is a schematic block diagram which shows the apparatus for generating a dummy signal.

Explanation of symbols

1 Microwave Transmitter 2 Microwave Receiver 3 Reflector A Detected Object

Claims (8)

A transmission means for transmitting the detection medium and a reception means for receiving the detection medium are arranged on one side across the monitoring area, and a reflection means for reflecting the detection medium is arranged on the other side to reflect from the transmission means. The detection medium is constantly transmitted toward the means and received by the receiving means.
For each received signal, the reflection position is calculated, and for the reference received signal based on the detection medium reflected by the reflecting means, the received intensity is output as it is or amplified, and the detection reflected by other than the reflecting means is detected. The received signal based on the medium is output with the received intensity as it is or attenuated,
A monitoring system that detects the presence of an object to be detected in a monitoring area when a reference reception signal is interrupted or attenuated.   The dummy signal indicating reflection by an object virtually existing at an arbitrary position between the transmission means and the reflection means is output when the reference reception signal is interrupted or attenuated. Monitoring system.   3. The monitoring system according to claim 2, wherein the dummy signal is amplified in the same manner as the reference received signal or attenuated in the same manner as the received signal based on the detection medium reflected by a means other than the reflecting means.   The detection medium is a rotating wave whose electric field distribution rotates in one of the clockwise or counterclockwise directions, or the electric field distribution is inclined at an angle of less than 90 ° with respect to a horizontal or vertical plane including the microwave traveling direction axis. The monitoring system according to any one of claims 1 to 3, wherein the microwave is an inclined linear wave, and the reflection means reflects the microwave incident on the reflection means an even number of times and sends the microwave to the reception means. . A transmission means for transmitting the detection medium and a reception means for receiving the detection medium are arranged on one side across the vehicle passage in the railroad crossing, and a reflection means for reflecting the detection medium is arranged on the other side. The detection medium is constantly transmitted from the transmission unit to the reflection unit, and is received by the reception unit.
For each received signal, the reflection position is calculated, and for the reference received signal based on the detection medium reflected by the reflecting means, the received intensity is output as it is or amplified, and the detection reflected by other than the reflecting means is detected. The received signal based on the medium is output with the received intensity as it is or attenuated,
When the reference reception signal is interrupted or attenuated even after the barrier fence has come off, it is judged that there are people or vehicles on the vehicle passage in the railroad crossing, and a warning is issued to the railcar approaching the railroad crossing Railroad crossing monitoring system.   6. The dummy signal indicating reflection by an object virtually existing at an arbitrary position between the transmission unit and the reflection unit is output when the reference reception signal is interrupted or attenuated. Railroad crossing monitoring system.   7. The level crossing monitoring system according to claim 6, wherein the dummy signal is amplified in the same manner as the reference reception signal or attenuated and output in the same manner as the reception signal based on the detection medium reflected by a means other than the reflection means.   The detection medium is a rotating wave whose electric field distribution rotates in one of the clockwise or counterclockwise directions, or the electric field distribution is inclined at an angle of less than 90 ° with respect to a horizontal or vertical plane including the microwave traveling direction axis. The railroad crossing monitoring according to any one of claims 5 to 7, wherein the reflection means transmits the microwave incident on the reflection means to the reception means after being reflected an even number of times. system.

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