JP2010127761A - Remote monitoring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a remote monitoring system for detecting changes in a plurality of events by one optical fiber and one monitoring apparatus, and reducing the total cost. <P>SOLUTION: The remote monitoring system includes: first and second detecting means 60, 40 connected by one optical fiber; and the monitoring apparatus 30 for causing a laser light within a predetermined wavelength range to enter the optical fiber, measuring a strength of a reflection light over the predetermined wavelength range, and detecting the change in the event to be monitored from detection results. The first detecting means detects whether the physical quantity to be monitored exceeds a preset predetermined level, and changes the light quantity by the predetermined quantity. The second detecting means changes a wavelength of the reflection light in response to a change in the physical quantity to be monitored. The monitoring apparatus detects the existence of the change in the physical quantity to be monitored at installation point of the first detecting means from the measured strength of the reflection light, and detects the change quantity of the physical quantity to be monitored at the installation point of the first detecting means from a peak value of the measured wavelength of the reflection light. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a remote monitoring system using an optical fiber, and more particularly, a change in an event in an area where a plurality of events or a portion requiring high detection accuracy and a portion having good detection accuracy are mixed even in the same event. The present invention relates to a remote monitoring system having a multi-sensing function for detecting an image.

  In recent years, various inventions related to remote monitoring systems have been made in order to capture a phenomenon that is a precursor to a natural disaster and to minimize damage caused by the natural disaster. For example, in sewer facilities, it is necessary to monitor the water level in preparation for overflow due to heavy rain, etc., and the optical water level detection is made by measuring the water level using the characteristics of an optical fiber called optical FBG (fiber Bragg grating). An invention related to a container has been proposed (for example, Patent Document 1).

In addition, inventions relating to monitoring systems using optical fibers for detecting rockfalls, rock collapses, landslides and precursors in mountainous areas have been proposed (for example, Patent Documents 2 and 3).
JP 2003-132774 A JP 2002-267549 A JP 2004-293277 A

  The inventions disclosed in Patent Documents 1 to 3 are all configured to detect a change in a specific event such as a rock fall, and thus, for example, a plurality of events such as a river increase and a rock fall in a certain area. When it is desired to detect a change in the number, it is necessary to install a plurality of monitoring systems. For this reason, there is a problem that the total cost becomes very high.

  An object of the present invention is to provide a remote monitoring system that can detect a change in a plurality of events with one optical fiber and one monitoring device and can reduce the total cost.

  Another object of the present invention is a location where a specific measurement value (analog output) is required and a location where it is sufficient to obtain whether or not the physical quantity to be monitored exceeds a predetermined level (high or low binary output). The object is to provide a remote monitoring system that can reduce the total cost in the case of coexistence.

In order to achieve the above object, a remote monitoring system according to the present invention provides:
An optical fiber laid so as to pass through a predetermined location in the monitoring area, first detection means installed at the predetermined location and connected to the optical fiber, and installed at the predetermined location and connected to the optical fiber A second detection means, a monitoring device that measures the intensity of reflected light over a predetermined wavelength range by entering laser light in a predetermined wavelength range into the optical fiber, and detects an event change to be monitored from the detection result; A remote monitoring system comprising:
The first detection means detects whether the physical quantity to be monitored exceeds a predetermined level set in advance and changes the light quantity by a predetermined amount, and the second detection means responds to a change in the physical quantity to be monitored. The wavelength of the reflected light is changed, and the monitoring device detects the presence or absence of a change in the physical quantity of the monitored object at the installation location of the first detection means from the intensity of the measured reflected light, and the peak of the wavelength of the measured reflected light The change amount of the physical quantity to be monitored at the location where the first detection means is installed is detected from the value.

  Here, preferably, the first detection unit is a reflection type detector whose reflected light amount changes when a physical quantity to be monitored exceeds a predetermined level.

  Further, preferably, a plurality of the first detection means are provided, and each first detection means is configured to output a reflected light amount having a different change amount when a physical quantity to be monitored exceeds a predetermined level.

  Preferably, the second detection means is a detector having a fiber grating. Further, a plurality of the second detection means are provided, and the fiber grating of each second detection means is configured to output reflected light having different center wavelengths.

  Further, preferably, the plurality of first detection means and the plurality of second detection means are installed at different locations. Further, the plurality of first detection means and a part of the plurality of second detection means may be installed at the same location.

  Preferably, the first detection means is an inundation detector or an open / close detector that detects whether or not the monitoring target water level exceeds a predetermined level, and the second detection means corresponds to the monitoring target water level. A water level gauge whose output changes.

  Alternatively, the first detection means may be a rock fall detector that detects the presence or absence of a rock fall, and the second detection means may be a earth pressure gauge whose output changes according to earth pressure. Further, the first detection means and the second detection means may be configured to monitor changes in physical quantities different from each other.

  According to the present invention, it is possible to realize a remote monitoring system that can detect changes in a plurality of events with a single device and can reduce the total cost. In addition, it is possible to reduce the total cost when there is a place where a specific measurement value (analog output) is required and a place where the physical quantity to be monitored exceeds a predetermined level (binary output) can be detected. A monitoring system can be realized.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

  FIG. 1 shows an embodiment of a remote monitoring system according to the present invention.

  The remote monitoring system of this embodiment uses an analog output sensor (high resolution sensor) for obtaining a specific measurement value (analog output) using FBG (fiber Bragg grating) or the like, and a physical quantity to be monitored is a predetermined amount. Using two types of sensors, binary output sensors (low resolution sensors) to obtain whether or not the level has been exceeded (binary output) and connecting these sensors to a single optical fiber It is characterized by a reduction.

  Specifically, an optical fiber 10 laid so as to pass through a place where a change in an event of interest in the monitored area is to be detected, and a light source 20 that makes laser light incident on the optical fiber 10 through a circulator 21; A monitoring device 30 that analyzes the reflected light from the optical fiber 10 and outputs measurement values and necessary information, analog output sensors 40a, 40b,... Connected in the middle of the optical fiber 10, and the middle of the optical fiber 10. Are provided with binary output sensors 60a, 60b,... Connected via optical couplers 22a, 22b... And branch fibers 11a, 11b.

  Here, the sensors 40a, 40b,... And the sensors 60a, 60b,... May be installed in different places or in the same place. If installed in different locations, more points can be monitored with the same number of sensors, and if installed in the same location, measurement results from different viewpoints can be obtained, making it possible to grasp the situation with higher accuracy. Become. As will be described later, the number of binary output sensors 60a, 60b,... That can be installed is smaller than the number of analog output sensors 40a, 40b,. It is thought that the number of sensors installed will increase.

  The circulator 21 functions as a directional coupler that allows the laser light emitted from the light source 20 to enter the optical fiber 10 and reflects the light reflected from the optical fiber 10 to the monitoring device 30. Analog output sensors (FBG sensors) 40a, 40b,... Using FBG are sensors in which a fiber core has a periodic refractive index modulation structure. Note that the sensor is not limited to the sensor using the FBG as long as a specific measurement value can be obtained, and a sensor of another principle may be used. Since the FBG sensor is a reflection type sensor, it is not necessary to provide a battery on the analog output sensor side, and there is an advantage that maintenance is simplified.

  In this embodiment, the fiber gratings are formed so that the FBG sensors 40a, 40b,... Have different peak wavelengths (center wavelengths) of the reflected waves. That is, the peak wavelength of the reflected wave of the FBG sensor 40a is λa, the peak wavelength of the reflected wave of the FBG sensor 40b is λb (λa ≠ λb), and so on. The light source 20 is configured to output laser light in a wavelength region including peak wavelengths λa, λb,... Of all sensors connected to the optical fiber 10. In this way, by using FBG sensors having different center wavelengths, it is possible to identify from which location the reflected wave is located when installed at a plurality of locations. As the laser light source, a continuous light source (CW light source) is generally used, but a pulsed light source may be used as long as the amount of light reflected from the sensor can be detected by a light receiver.

  The binary output sensors 60a, 60b,... Are on / off sensors that have a reflecting mirror and generate strong reflected light when the amount of change in the monitored event exceeds a predetermined level (threshold). Something like this is possible. By using such a reflection type sensor as the binary output sensor, there is an advantage that it is not necessary to provide a battery on the side of the binary output sensor and maintenance is simplified. It is desirable that the binary output sensors 60a, 60b,... Are configured to have different amounts of reflected light at the time of detection. Thereby, it becomes possible to identify the reflected light from the sensor installed at which location from the intensity of the reflected light. In the example of FIG. 1, it is assumed that the reflection intensity Ra of the sensor 60a is set to be higher than the reflection intensity Rb of the sensor 60b, that is, Ra> Rb.

  Next, the operation of the remote monitoring system of this embodiment will be described using the waveform diagram of FIG.

  The monitoring device 30 analyzes the wavelength of the reflected light incident from the optical fiber 10 and detects the level of each wavelength. FIG. 2 shows a waveform example of reflected light detected by the monitoring device 30. In FIG. 2, a solid line A is a reflected waveform in a normal state in which all sensors do not capture a change in an event to be monitored, and peaks appear at wavelengths λa and λb. If the FBG sensor 40a detects a change in the event to be monitored, the peak point of the waveform deviates from λa. If the FBG sensor 40b detects the change in the event to be monitored, the peak point of the waveform deviates from λb. Therefore, the monitoring device 30 can calculate the amount of change, that is, the measured value, from the difference between the center wavelength of each FBG sensor known in advance and the peak point of the reflected light.

In FIG. 2, a broken line B indicates a waveform when the sensor 60b detects that the change in the monitored event exceeds the threshold value, and a dotted line C indicates a change in the monitored event by the sensor 60a. The waveform in the case where it has been detected that it has been exceeded, and the alternate long and short dash line D is the waveform in the case where both the sensors 60a and 60b have detected that the event change to be monitored has exceeded the threshold value. Accordingly, the monitoring device 30 sets the determination levels in advance as shown by TL1, TL2, and TL3 in FIG. 2, and compares these determination levels with the intensity of the reflected light. It can be identified whether the event has changed and which sensor is detecting the event change.
(Example)
Next, a more specific example of the remote monitoring system according to the above embodiment will be described. Here, examples of remote monitoring systems configured as shown in Fig. 1 include water level monitoring systems that monitor water levels in sewers and rivers, rockfall and landslide monitoring systems in mountainous areas, and intrusion monitoring systems in restricted access areas or facilities. Think. In each system, there is a difference in the specifications or functions of the analog output sensor to be used and the binary output sensor. Table 1 below summarizes the sensor functions and combinations required for each system.

なお、表１においては、アナログ出力センサをセンサ１、２値出力センサをセンサ２として記載している。

In Table 1, the analog output sensor is described as sensor 1, and the binary output sensor is described as sensor 2.

  As shown in Table 1, in the water level monitoring system, a water level meter capable of detecting the water level value is used as the sensor 1, and an inundation detector or an open / close detector capable of detecting whether or not the water level has exceeded a predetermined level is used as the sensor 2. The As the water level gauge, a sensor using FBG disclosed in Patent Document 1 can be considered. As the inundation detector, one having a configuration as shown in FIGS. 3 and 4 can be considered (described later). Further, as the open / close detector, for example, a reflection mirror disposed opposite to the end of the optical fiber and a shutter provided between them may be configured to operate the shutter by moving the float up and down. .

  In the rock fall monitoring system, a displacement meter capable of detecting a displacement value of a rock or a formation or a soil pressure gauge capable of detecting a change in the weight of the soil is used as the sensor 1, and a rock fall detector capable of detecting a rock fall is used as the sensor 2. A sensor using an optical fiber disclosed in Patent Document 3 can be used as a displacement gauge or earth pressure gauge, and a sensor using an optical fiber disclosed in Patent Document 2 can be used as a falling rock detector. In this way, a rockfall monitoring system that can collect information from many monitoring points can be realized at low cost by using a displacement gauge or earth pressure gauge and a rockfall detector separately.

  In the intrusion monitoring system, a load meter capable of detecting the load of the intruder is used as the sensor 1, and a load detector capable of detecting whether a moving object exceeding a predetermined weight has entered the sensor 2. It is conceivable that the load meter has a configuration according to the displacement meter or earth pressure meter, a configuration according to the water level meter (FBG sensor), and the load detector has a configuration according to the rock fall detector.

  In addition, the monitoring system provided with the load meter and the load detector can be applied also to the falling rock monitoring system. In addition, the monitoring system is not limited to the above-described configuration, and a multi-monitoring system that monitors different types of events by combining, for example, a water level gauge and a rockfall detector is also possible. By monitoring different types of events, it becomes possible to understand and predict the occurrence of natural disasters such as landslides in more detail.

As described above, since the conventional multi-monitoring system for monitoring different types of events had to be installed as separate systems, it was necessary to provide two optical fibers and a measuring device, resulting in an increase in cost. The remote monitoring system according to the present embodiment has an advantage that the total cost can be greatly reduced because the detection means for detecting the change of different events is connected to one optical fiber.
(Concrete example)
As an example, a specific example in the case of applying the present invention to a water level monitoring system that wants to detect a plurality of water levels such as sewer facilities will be described.

  In this water level monitoring system, a water level meter using an FBG (fiber Bragg grating) is used as the sensor 1, and an inundation detector capable of detecting whether or not the water level has exceeded a predetermined level is used as the sensor 2.

  The optical fiber 10 is laid so as to pass through a place where the water level in the monitoring area is desired to be detected. In the middle of the optical fiber 10, optical water level gauges 40a, 40b... Using FBG are provided. The optical water level gauges 40a, 40b,... Are composed of, for example, a diaphragm that converts water pressure into strain and an FBG that measures the strain of the diaphragm.

  Further, in the middle of the optical fiber 10, the configuration is simpler and less expensive than the optical water level gauges 40a, 40b,... That detect whether or not the water level at the monitoring place has reached a predetermined level set in advance. The immersion detectors 60a, 60b,... Are connected via the optical couplers 22a, 22b,. In this way, a water level monitoring system that can collect information from many monitoring points can be realized at low cost by using the optical water level meter and the inundation detector separately.

  3 and 4 show an example of an inundation detector suitable for use in a water level monitoring system. FIG. 3 is a schematic view of the inundation detector, and FIG. 4 is a block diagram showing the internal structure. As shown in FIG. 3, the inundation detector 60 of this embodiment includes a magnetic detection proximity switch 62 housed and fixed in the upper half of the cylindrical protective cover 61, and a lower half of the protective cover 61. The end of branch fiber 11a, 11b, 11c ... is connected to proximity switch 62, and permanent magnet 64 is placed on the upper surface of float 63.

  The proximity switch 62 is a sensor using the magnetic Faraday effect, and as shown in FIG. 4, a lens 65 facing the end face of the optical fiber, a birefringent element 66, a ring-shaped magnet 67, and this The first Faraday rotator 68a, the second Faraday rotator 68b, and the reflection mirror 69 are arranged in series.

  In the inundation detector of this specific example, when the float 63 rises due to the rise in water level and the permanent magnet 64 approaches the proximity switch 62, the polarization plane of the internal Faraday rotator 68b rotates and the light incident from the end face of the optical fiber is received. By being strongly reflected by the reflection mirror 69, the fact that the water level has risen above a predetermined level is output as reflected light. The amount of reflected light can be changed by adjusting the reflectance of the reflecting mirror 69 or the light transmittance of the Faraday rotator, for example.

  FIG. 5 shows the measurement result of the reflected light amount in the experimental water level monitoring system created by the present inventors. In the experimental water level monitoring system, in the configuration of FIG. 1, a water level meter is used as the sensors 40a and 40b, and an inundation detector is used as the sensors 60a and 60b, and the water level meters with the center wavelengths of 1552 nm and 1554 nm are used. As it was used, the amount of reflected light from the water immersion detectors 60a and 60b was set so that 60a was larger.

  In FIG. 5, the horizontal axis represents the wavelength of light, and the vertical axis represents the intensity of the reflected light amount. OFF1 / OFF2 is a waveform of the reflected light amount when both of the water immersion detectors 60a and 60b are in an off state, and OFF1 / ON2 is a waveform of the reflected light amount when the water immersion detector 60a is in an off state and 60b is in an on state. Further, ON1 / OFF2 is a waveform of the reflected light amount when the inundation detector 60a is in the on state and 60b is in the off state, and ON1 / ON2 is a waveform of the reflected light amount when both the inundation detectors 60a and 60b are in the on state.

  From FIG. 5, assuming that the reflected light level when the two flooding detectors are both off (OFF1 / OFF2) is 0 dB, the reflected light level when 60a is off and 60b is on (OFF1 / ON2) is 3. When 0 dB, 60 a is on and 60 b is off (ON1 / OFF2), the amount of reflected light is 4.8 dB, and when both are on (ON1 / ON2), the reflected light level is 6.0 dB. Since there is a level difference of 1.2 dB or more, it can be sufficiently discriminated. In addition, although the case where it applied to the water level monitoring system of a sewer installation was demonstrated in the said specific example, it is applicable also to water level monitoring systems, such as a river, a dam, and a pond.

  Although the invention made by the present inventor has been specifically described based on the embodiment, the present invention is not limited to the above embodiment. For example, in the above-described embodiment, the case where an optical water level meter using FBG is used as a water level meter has been described. However, other water level meters (for example, optical path differences disclosed in Japanese Patent Application Laid-Open No. 2000-111361 are used). The present invention can also be applied when using a sensor that uses a water level gauge.

  Further, in FIG. 1 showing the embodiment, two analog output sensors and two binary output sensors are connected to one optical fiber, but 10 or more analog output sensors are 3 binary output sensors. It is also possible to connect more than one. However, regarding the binary output sensor, it is desirable to stop it within several in order to secure the discrimination level.

  Further, in the above embodiment, the optical fiber 10 is configured so that the incident light travels in one direction. However, the optical fiber 10 is returned to the monitoring device 30 side, and light is also incident from the other end. You may comprise so that switching is possible. As a result, even if the fiber is cut halfway due to an accident, it is possible to obtain measurements at more monitoring points (all monitoring points if there is only one cutting point) by performing measurement with the light incident end changed. Is possible.

  Furthermore, the optical fiber may be used as an optical line for communication as well as monitoring. For example, an optical communication device is installed at both ends of the optical fiber, and one of the optical fiber ends is configured so that the monitoring device and the optical communication device can be switched by an optical switching device. In this case, when a call is necessary, a call using an optical communication device can be performed. As an optical communication device, for example, there is a communication device (Japanese Patent Laid-Open No. 5-19184) that modifies propagation light by changing an optical fiber bending diameter.

  In the above description, the case where the present invention is mainly applied to a water level monitoring system, a falling rock monitoring system, and an intrusion monitoring system has been described. However, the present invention is not limited to this. be able to.

It is a block diagram which shows one Embodiment of the remote monitoring system which concerns on this invention. In the remote monitoring system of FIG. 1, it is a wave form diagram which shows the waveform example of the reflected light which injects into a monitoring apparatus from an optical fiber. It is a general-view figure which shows one Example of an inundation detector suitable for using for a water level monitoring system. It is a block diagram which shows the internal structure of the water immersion detector of FIG. It is a wave form diagram which shows the result of having measured the reflected light quantity in the experimental water level monitoring system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical fiber 11 Branch fiber 20 Light source 21 Circulator 22 Optical coupler 30 Monitoring apparatus 40 Analog output sensor (FBG sensor)
60 binary output sensor (on / off sensor)
61 Protective cover 62 Magnetic detection type proximity switch 63 Float 64 Permanent magnet 65 Lens 66 Birefringent element 67 Ring magnet 68a First Faraday rotator 68b Second Faraday rotator 69 Reflective mirror

Claims (8)

An optical fiber laid so as to pass through a predetermined location in the surveillance area;
First detection means installed at the predetermined location and connected to the optical fiber;
Second detection means installed at the predetermined location and connected to the optical fiber;
A remote monitoring system comprising: a monitoring device that enters laser light of a predetermined wavelength range into the optical fiber, measures the intensity of reflected light over a predetermined wavelength range, and detects a change in an event to be monitored from the detection result Because
The first detection means detects whether the physical quantity to be monitored exceeds a predetermined level set in advance, and changes the light amount by a predetermined amount,
The second detection means changes the wavelength of the reflected light according to the change in the physical quantity to be monitored,
The monitoring device detects the presence or absence of a change in the physical quantity to be monitored at the installation location of the first detection means from the measured reflected light intensity, and installs the first detection means from the measured peak value of the wavelength of the reflected light. A remote monitoring system for detecting a change amount of a physical quantity to be monitored at a location.   2. The remote monitoring system according to claim 1, wherein the first detection unit is a reflection-type detector that changes a reflected light amount when a physical quantity to be monitored exceeds a predetermined level.   A plurality of the first detection means are provided, and each first detection means is configured to output a reflected light amount having a different change amount when a physical quantity to be monitored exceeds a predetermined level. The remote monitoring system according to claim 2.   The remote monitoring system according to claim 1, wherein the second detection unit is a detector having a fiber grating.   The remote monitoring system according to claim 4, wherein a plurality of the second detection means are provided, and the fiber grating of each second detection means is configured to output reflected light having different center wavelengths.   The remote monitoring system according to claim 5, wherein the plurality of first detection units and the plurality of second detection units are installed at different locations.   The remote monitoring system according to claim 5, wherein a part of the plurality of first detection means and a part of the plurality of second detection means are installed at the same location.   The first detection means is an inundation detector or an open / close detector that detects whether or not the monitoring target water level exceeds a predetermined level, and the second detection means is a water level whose output changes according to the monitoring target water level. The remote monitoring system according to claim 1, wherein the remote monitoring system is a total.

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