JP2004109003A - Optical rainfall measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical rainfall measuring device capable of extending the distance from a rainfall observation point to a remote monitoring point, and increasing the number of connections of rain gages to a single core optical fiber. <P>SOLUTION: A tensile strain is generated in an optical fiber sensor 6 having an FBG element by a tipping operation of a tipping bucket 12 by using a tipping-bucket rain gage. A change in the reflection wavelength caused by the strain is examined, to thereby perform tipping detection, and the number of times of the wavelength change is counted, to thereby enable rainfall measurement by each rain gage 1 at a remote place. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides an optical fiber sensor that attaches an optical fiber sensor for detecting the falling of a falling hill to a falling hill type rain gauge, so that it is possible to perform rainfall observation at a plurality of points in real time with a single device in a remote place. The present invention relates to a rainfall measuring device.
[0002]
[Prior art]
Generally, rainfall observation is conducted by installing on-site (observation points) mechanical self-recording or electric (data logger) observation equipment certified by the Japan Meteorological Agency sold by weather observation equipment manufacturers. It was a target. However, they cannot be used where there is no power supply, and require an observer to read and contact the data. In addition, there are many problems such as the equipment being damaged due to a lightning surge or the like and becoming unusable.
[0003]
Also, where there is no commercial power source, solar cells are used to transmit data wirelessly. In this case, data transmission frequency is once every 30 minutes from the viewpoint of power supply capacity and system cost. Or, it is restricted to once every 10 minutes at the earliest, and real-time data collection is not possible.
[0004]
Therefore, as a method for solving these problems, various optical rain gauges have already been developed and some of them have been put to practical use. For example, one proposed by the present applicant is to use a Wiegand element that generates a voltage by the action of a magnetic force, use an electromotive force of the element to make a light-emitting diode glow, and count the number of times of light emission.
[0005]
Also, as another method, direct current light is output from the monitoring device to the optical fiber of the rain gauge, and when the rainfall reaches a certain level, the light is cut off by the operation of the rain gauge, and the number of cutoffs is counted to reduce the rainfall. There are also things to ask for.
[0006]
[Problems to be solved by the invention]
The conventional optical rain gauge measures the presence or absence of a light transmission state, and is therefore applicable only when the distance from the observation point to the monitoring point where data is collected and processed is relatively short. Alternatively, in data collection using a single-core optical fiber, there is a problem that a single device cannot monitor a plurality of points unless the wavelength from each observation point is changed using a duplexer or the like.
[0007]
The present invention provides an optical rainfall measuring device that eliminates these problems and has a relatively simple structure.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, in the present invention, an overhang type rain gauge, an optical fiber sensor using an FBG element capable of giving a tensile strain when the overturning overturn is applied, and a reflection wavelength from the optical fiber sensor are measured. A reflection wavelength measuring device for measuring rainfall by counting the number of changes in the reflection wavelength measured by the reflection wavelength measuring device.
[0009]
In this rainfall measuring device, the shape of the optical fiber sensor is always an ellipse or a ring having a shape similar to the ellipse, and one end in the long axis direction of the ring is a fixed portion, and the other end is a force receiving portion. It is preferable that a required play is generated between the tension applying portion that applies tensile strain and the tension applying portion.
[0010]
In addition, the balance weight immediately below the center of the falling slab is used as a tension applying part to enter the optical fiber sensor loop, and the displacement of the balance weight due to the falling of the slab is used to apply tensile strain to the force receiving part of the optical fiber sensor. Or a guide member for holding the force receiving portion of the optical fiber sensor in the engagement position with the tension applying portion, or the application of the tensile strain to the optical fiber sensor is considered when the tipping roll falls to one side. It is also preferable to do so.
[0011]
Further, in the rainfall measurement using the apparatus of the present invention, the reflection wavelength of the FBG element measured by the reflection wavelength measurement apparatus is constantly monitored, and the difference between the current measurement wavelength and the past measurement wavelength close to the current time is obtained. It is preferable to determine that the falling cell has fallen only when the value exceeds a predetermined value, count the number of times of falling, and obtain the measured rainfall from the count number per time.
[0012]
[Action]
The device according to the present invention generates tensile strain in the optical fiber sensor by utilizing the overturning operation of the overturning box. Although the tensile strain that can be applied to the optical fiber by this method is not so large, since the FBG (Fiber Bragg Grating) element known as a high-sensitivity element is used, even if the distance from the observation point to the monitoring point becomes long, The fall detection of the fall measure can be performed.
[0013]
When tensile strain occurs in the FBG element, the reflection wavelength of light changes. If the wavelength change is monitored by a wavelength meter, it is possible to simultaneously detect the presence or absence of the overturning at a plurality of observation points using a single-core optical fiber, and it is possible to perform simultaneous observation at multiple points in real time.
[0014]
In addition, when the optical fiber sensor using the FBG element is brought into contact with the tension applying portion without play, the falling of the falling box to one side is hindered by the rigidity of the optical fiber, and the timing of the falling of the right and left boxes is delayed. However, accurate measurement cannot be expected due to the deviation, but the optical fiber sensor is made into a ring similar in shape to the shape when the pulling force is applied in advance, and between the receiving part and the tension applying part of the sensor. In the case of the play, since the pulling force is applied to the force receiving portion from the tension applying portion at the time when the box has fallen over, the above-described problem does not occur.
[0015]
In addition, the one that uses the balance weight for adjusting the falling timing provided in the falling rain gauge as a tension applying part has an advantage that the current rain gauge can be used without special modification.
[0016]
Further, a device provided with a guide for preventing the force receiving portion of the optical fiber from coming off from the tension applying portion prevents malfunction.
[0017]
The fall detection of the square can also detect the fall of each of the left and right squares. In this case, however, it is necessary to provide two sets of FBG elements having different wavelengths in order to distinguish which square has fallen. In multi-point observation using a single-core optical fiber, the total number of observation points that can be connected to one monitoring device is undesirably reduced due to an increase in the number of elements. On the other hand, the one that detects only the fall of one side of the overturning cell is one set of FBG elements used for one rain gauge, and the number of observation points that can be monitored simultaneously using one optical fiber increases. I can make it.
[0018]
In addition, if the initial value is fixed in the measurement of the wavelength change of the FBG element and the current wavelength change is obtained by comparing with the initial value, the wavelength change due to the temperature change may be erroneously recognized as the wavelength change due to the falling of the box. Occurs. This is because the tension that can be applied to the optical fiber by the overturning force of the box is limited, and a large wavelength change cannot be obtained. According to the measuring method of the present invention described later, the erroneous recognition can be prevented, and the reliability of the system is improved.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an overall configuration of an observation system using the rainfall measuring device of the present invention.
[0020]
In the figure, 1 is an optical rain gauge installed at each observation point, 2 is a monitoring control device installed in a remote monitoring station building, 3 is an optical switch provided as needed, 4 is a reflection wavelength (distortion) of an FBG element. 5) denotes an optical fiber. In the figure, two optical fibers 5 are provided, and a number of optical rain gauges 1 are serially connected to each optical fiber 5.
[0021]
In the method of measuring the wavelength of the FBG element, the processing speed by the wavelength meter is relatively high, and the measurement can be performed at a cycle of 50 Hz depending on the processing method. Therefore, by switching the connection state of each optical fiber using the optical switch 3, it is possible to monitor more rain gauges with one monitoring and control device 2. FIG. 1 shows an example thereof.
[0022]
FIG. 2 shows the internal structure of the optical rain gauge. The optical rain gauge 1 includes a falling rain gauge having a falling cylinder 12, a funnel 13 for alternately injecting rainwater into left and right cells, and two drainage tubes 14 in a cylinder 11, and a falling cell. An optical fiber sensor 6 for detecting the above and an accessory element described later. The overhang type rain gauge may be a commercially available product.
[0023]
3 and 4 show the details of the main part of the rain gauge 1. FIG. Here, two types of guides 7 and 8 and a stopper 9 are provided as accessory elements. The optical fiber sensor 6 is a sensor having an FBG element, and is installed as a ring close to an ellipse. This optical fiber sensor 6 is connected to the optical fiber 5 in series.
[0024]
In the falling rain gauge, a balance weight 15 is hung directly below the center of the rack, and the force receiving portion 6a of the optical fiber sensor 6 plays around the outer periphery of the balance weight 15 as shown in FIG. G wrapped around. The other end of the optical fiber sensor 6 in the major axis direction is wound around the outer circumference of one of the drainage tubes 14 using the drainage tube 14 as a support member, and is stopped by a stopper 9 via a cushion material such as rubber so as not to come off. It is fixed.
[0025]
It is preferable to fix the optical fiber sensor 6 to the drainage tube 14 by setting the bending radius to 35 mm or more so as to minimize the loss caused by winding. The bending radius is preferably determined so that the receiving portion 6a also generates as little tension as possible due to bending. If the force receiving portion 6a comes off the balance weight 15 or the fitting position with respect to the balance weight varies, the falling detection of the cell becomes unstable or undetectable. It is preferable to provide a guide 7 for preventing the optical fiber from coming off and locking the balance weight at a fixed position and a guide 8 for supporting the optical fiber loop in the longitudinal direction. The projected length of the illustrated guide 7 is preferably shortened in order to prevent the balance weight 15 from being unbalanced. When the guide 8 is provided, the projected length of the guide 7 does not need to be too long.
[0026]
Further, if the optical fiber is caught on a surrounding object, there is a possibility that the wire may be disconnected. Therefore, it is preferable to provide a protective cover 10 for preventing the disconnection. It is preferable to have such a role, because no extra accessories are required.
[0027]
The guide may be as shown in FIG. The guide 7A shown in FIG. 6 stores and holds the optical fiber in the U-slot, so that the radius of curvature and the displacement of the optical fiber 6 during the application of the pulling force of the force receiving portion 6a are unlikely to occur.
[0028]
In the optical rain gauge 1 configured as described above, when rainwater is injected into the box and the falling box 12 falls on one side, the balance weight 15 is displaced, and the play G between the light receiving section 6a and the force receiving section 6a is reduced. Then, the play G disappears before the box is overturned (see FIG. 5), and the tension is applied to the optical fiber sensor 6 by further overturning of the box.
[0029]
At this time, if the receiving portion 6a is pulled as shown in FIG. 5 and the bending radius of the receiving portion 6a becomes too small, the bending and extension of the receiving portion 6a are repeated, which is not preferable in terms of durability. If the wavelength change required for detection can be caused only by pulling by the balance weight 15, it is better not to make the change in the bending radius of the force receiving portion 6a too large.
[0030]
When the falling box 12 returns to the neutral position or falls down to the opposite side, the tension applied to the force receiving portion 6a is lost. Therefore, the rainfall can be measured in a certain unit, for example, 0.5 mm unit or 1 mm unit by counting the number of repetitions of the change of the reflection wavelength depending on the presence or absence of the tensile strain.
[0031]
FIG. 7 is a measurement example of the reflection wavelength. A plurality of FBG elements having different center wavelengths are inserted into a single-core optical fiber, and the deviation of the reflected wave from each element from the center wavelength is measured. , Count the number of operations. Then, the amount of rain is obtained from the number of counts per hour. FIG. 7 shows a state in which the wavelength has shifted at a certain wavelength until the overturning cell operates, but the wavelength shifts due to the operation of the overturning cell. Since the reflection wavelength of the FBG element also changes depending on the temperature as shown in FIG. 7B, there is a possibility that the wavelength change due to the temperature change is erroneously recognized as the wavelength change due to the operation of the overturn when compared with the fixed initial value. . In order to eliminate the misconception, when a wavelength shift that is a predetermined value or more is observed as a relative value with respect to the immediately preceding value, it is determined that the tipping box has fallen.
[0032]
Specific examples of the determination method are listed below.
[0033]
Method 1: As shown by (1) in FIG. 8 (a), a difference between two consecutive sampling values is obtained, and when the difference exceeds a certain value, it is determined that there is a change.
[0034]
Method 2: When there is a change in (1), as shown by (2) in FIG. 8 (a), the immediately preceding data (a) and the data after the change are compared several times to determine the continuity. It is determined that there is a change when the change has continued for a predetermined number of times or more.
[0035]
Method 3: As shown by {circle around (3)} in FIG. 8 (b), a difference between two points of data at intervals shorter than the assumed period of change is obtained, and when the difference exceeds a certain value. Judge that there is a change.
[0036]
Method 4: As shown by {circle around (4)} in FIG. 8 (c), a difference is obtained with respect to the average value of data several times before and after two points separated by an interval shorter than the assumed period of change, and there is a difference. It is determined that there is a change when it changes by a certain value or more.
[0037]
Method 5: As shown by {circle around (5)} in FIG. 8 (b), a difference between two points of data at intervals shorter than the assumed period of change is obtained, and the difference exceeds a certain value, and When the state has continued for a predetermined number of times or more, it is determined that there is a change.
[0038]
Among these methods, the method 2 and the method 5 in which the continuity is evaluated to make a determination also prevent erroneous determination due to noise, and serve to further enhance the reliability of the system.
[0039]
If the determination function by any one of the above methods 1 to 5 is added to the monitoring and control device 2 of FIG. 1, automatic observation of rainfall can be performed.
[0040]
【The invention's effect】
As described above, the rainfall measuring device of the present invention causes a fiber strain having an FBG element to generate a tensile strain by the overturning operation of the overturning type rainfall gauge, and the change of the reflection wavelength due to the distortion is generated. Since the rainfall is obtained by counting the number of times, the drawbacks of the conventional rainfall measuring device using the optical rain gauge can be eliminated. That is, the distance from the observation point to the monitoring point can be extended, the number of observation points corresponding to one optical fiber can be increased, and a system capable of real-time and detailed observation of a wide area can be constructed. This device is inexpensive and highly reliable because of the features of the optical rain gauge.
[0041]
In the case of checking the falling motion of the falling box by the method of the present invention, erroneous determination is prevented and the measurement accuracy is improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing an overall configuration of an observation system using the rainfall measuring device of the present invention; FIG. 2 is a diagram showing an overall configuration of an optical rain gauge; FIG. 3 is a diagram showing details of a main part of the optical rain gauge; FIG. 4 is a plan view showing a situation when the box is overturned. FIG. 6A is a plan view showing another example of the guide. FIG. FIG. 7A is a diagram showing a measurement example of a reflection wavelength, FIG. 7B is a diagram showing a wavelength change due to a temperature change, and FIG. 8 is an explanatory diagram of a judgment method for preventing erroneous judgment. Description】
DESCRIPTION OF SYMBOLS 1 Optical rain gauge 2 Monitoring and control apparatus 3 Optical switch 4 Wavelength meter 5 Optical fiber 6 Optical fiber sensor 6a having FBG element Power receiving parts 7, 7A, 8 Guide 9 Stopper 10 Protective cover 11 Cylinder 12 Falling down funnel 14 Drainage cylinder 15 Balance weight 16 Base plate G Play

Claims (6)

A falling-bulb-type rain gauge, an optical fiber sensor using an FBG element capable of giving a tensile strain when the falling-bulk falls down, and a reflection wavelength measuring device for measuring a reflection wavelength from the optical fiber sensor. An optical rainfall measurement device that counts the number of changes in the reflected wavelength measured by the measurement device to measure rainfall. The constant shape of the optical fiber sensor is an ellipse or a ring having a shape similar to the ellipse, one end in the long axis direction of the ring is a fixed portion, the other end is a force receiving portion, and the force receiving portion and the tension application to apply tensile strain thereto. The optical rainfall measuring device according to claim 1, wherein a required play is generated between the optical rainfall measuring device and the portion. The balance weight just below the center of the falling slab is used as a tension applying part and enters the loop of the optical fiber sensor, and a tensile strain is applied to the force receiving part of the optical fiber sensor using the displacement of the balance weight due to the falling of the slab. 3. The optical rainfall measuring device according to claim 2, wherein: The optical rainfall measuring device according to claim 2 or 3, further comprising a guide member for holding the force receiving portion of the optical fiber sensor at an engagement position with the tension applying portion. The optical rainfall measuring device according to any one of claims 1 to 4, wherein the application of the tensile strain to the optical fiber sensor is considered when the falling slop falls to one side of the falling slop. A rainfall measurement method using the rainfall measurement device according to any one of claims 1 to 5, wherein the reflection wavelength of the FBG element measured by the reflection wavelength measurement device is constantly monitored, and the current measurement wavelength and the current measurement wavelength are measured. A rainfall measuring method for determining a difference between measured wavelengths in the past in the past, determining that a falling box has fallen only when the difference exceeds a predetermined value, counting the number of times of falling, and obtaining a measured rainfall from a count per time.

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