JP5062489B2 - Sensor element and landslide detection device - Google Patents

Description

  The present invention relates to a sensor element used for detection of landslide and a landslide detection apparatus using the sensor element.

  There are concerns about the occurrence of landslide disasters in places such as mountains and steep slopes. Conventionally, as a device for detecting the occurrence of a landslide, Patent Document 1 discloses a landslide sediment collapse monitoring alarm device. The landslide earth and sand collapse monitoring and alarm device disclosed in this gazette drives a stop pin or pile into a place where earth and sand such as a slope are supposed to pass, and connects a limit or proximity switch to the position combined with the end of the stop pin or pile. The movement of the stop pin or pile is detected by a limit or proximity switch.

  As other conventional technologies, a wire is attached to a place where earth and sand are supposed to pass, and a landslide is detected when the wire is cut, or the terrain is photographed with a camera, and the obtained image is analyzed to analyze the landslide. Some are detected.

Utility Model Registration No. 3017455

However, in the landslide earth and sand collapse monitoring alarm device disclosed in the above-mentioned publication, limit switches and proximity switches excellent in weather resistance are expensive, and there is a problem that the entire device becomes expensive. In particular, when it is desired to detect the range of landslides, a large number of limit switches or proximity switches are required, resulting in a considerable amount of money.
In addition, in the case of using a wire, there are many false detection factors due to fluctuations of the wire caused by wind or cuts by animals.
In addition, in the case of image analysis with a camera, the number of cameras can be reduced because the surveillance area can be taken in a wide range, but the unit price per unit is much higher than the limit switch and proximity switch, Also, sufficient performance cannot be achieved in bad weather such as fog and heavy rain.

  SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has a sensor element that can be used without any problem even in bad weather, can be used without any problem even in bad weather, and can be realized at low cost, and a landslide using the sensor element. An object is to provide a detection device.

The above object of the present invention is achieved by the following configuration.
(1) A sensor element for converting electrical energy into mechanical energy, a piezoelectric element, a diaphragm having the piezoelectric element on one surface and the other surface serving as a detection surface, and the piezoelectric element of the diaphragm A case that supports the diaphragm so as to form a space around the diaphragm and that the detection surface of the diaphragm is an outer surface, and a protrusion that is positioned on the detection surface side of the diaphragm and protrudes so as to press the detection surface And a flexible member elastically supported by the case.

(2) The flexible member is a cantilever having one end fixed to the case and the other end extending to a substantially central portion of the detection surface by projecting the protrusion. The sensor element described.

(3) The sensor element according to (1), wherein the flexible member is a doubly-supported beam in which the protrusion is protruded substantially in the center and both ends are fixed to the case.

(4) The sensor element according to (1), wherein the flexible member is a diaphragm in which the protrusion is protruded substantially at the center and a peripheral edge portion is fixed to the case.

(5) A landslide detection device for detecting landslide,
A plurality of the sensor elements according to any one of (1) to (4) above, a signal generating means for generating a sine wave signal whose frequency changes with time in a predetermined range, and a plurality of the above-mentioned sensor elements Switching means for switching one sensor element at a time and applying a sine wave signal generated by the signal generating means, and change in current flowing in the sensor element to which a sine wave signal is applied every time switching is performed by the switching means And detecting means for detecting earth and sand by detecting a change in frequency characteristics of the captured voltage waveform.

(6) A landslide according to (5), characterized in that the landslide includes communication means that can be connected to an electric communication line and that transmits earth and sand detection information obtained from the detection means using the electric communication line. Detection device.

  According to each of the above configurations, since the flexible member is provided on the detection surface side of the diaphragm, the flexible member is easily deformed even with low-density sand or earth that is difficult to detect with the diaphragm alone. Then, the protrusion projected on the flexible member touches the diaphragm and can be detected. Moreover, since the piezoelectric element has high detection accuracy, it can be detected with high accuracy. In addition, the sensor element can be manufactured at low cost by using the piezoelectric element. Furthermore, the sensor element using a piezoelectric element has almost no false detection factor, and can be used without problems even in bad weather such as fog or heavy rain.

  As a landslide detection device, a plurality of sensor elements are installed in a place such as a mountainous area or a steep slope where the occurrence of a landslide disaster is a concern, thereby detecting a landslide and a range of landslides.

  Moreover, the landslide detection information obtained by the detection means using the telecommunication line can be monitored remotely via the communication means.

  It is possible to provide a sensor element that can be used without any problem in landslide detection, can be used without problems even in bad weather, and can be realized at a lower cost, and a landslide detection apparatus using the sensor element.

DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments for carrying out the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a landslide detection apparatus according to an embodiment of the present invention.
The landslide detection device 1 according to the present embodiment is installed in a mountainous area, a steep slope, or the like and detects the occurrence of a landslide, but it can also detect an avalanche in addition to a landslide.

  In FIG. 1, the landslide detection device 1 of the present embodiment includes a plurality of sensor elements 10, a switch 19, a voltage controlled oscillator 20, amplifiers 21 to 23, a resistor 24, a differential amplifier 25, A four-quadrant analog multiplier 26, a low-pass filter 27, a control unit 28, a communication unit 29, and an antenna 30 are configured. The sensor element 10 converts an electrical signal into a mechanical signal and outputs it.

2 is a plan view showing the sensor element 10, and FIG. 3 is a cross-sectional view taken along line AA in FIG.
In these drawings, the sensor element 10 includes a piezoelectric ceramic (piezoelectric element) 11, a vibration plate 12 having the piezoelectric ceramic 11 on one surface and the other surface serving as a detection surface, and a pedestal 13 that supports the vibration plate 12. A case 14 that forms a space around the piezoelectric ceramic 11 of the diaphragm 12 and supports the diaphragm 12 via the pedestal 13 so that the detection surface of the diaphragm 12 becomes an outer surface, and a detection surface of the diaphragm 12 A cantilever (hereinafter referred to as a “cantilever”) 15 as a flexible member that is positioned on the side, one end of which is fixed to the pedestal 13 and the other end of which is elastically supported by reaching the center of the detection surface of the diaphragm 12. It is prepared for. The piezoelectric ceramic 11 is connected to the switching unit 15 via a cable 16.

The cantilever 15 is provided to compensate for the point that the diaphragm 12 cannot sense low-density sand or earth, and is formed in an L-shaped cross section, and one end is fixed to the case 14 via the pedestal 13. The other end (tip) is extended to the central portion of the diaphragm 12. A protrusion 15 a protruding in a mountain shape is provided on the surface of the other end portion of the cantilever 15 facing the diaphragm 12.
FIG. 4 is a diagram illustrating a state when earth and sand are detected. The cantilever 15 is displaced toward the detection surface side of the diaphragm 12 by the weight of the earth and sand 35, and the protrusion 15 a pushes the center of the detection surface of the diaphragm 12. The vibration device composed of the diaphragm 12 and the piezoelectric ceramic 11 has the highest sensitivity at the center of the detection surface, and thus reacts immediately to detect earth and sand. As a material used for the cantilever 15, carbon steel or carbon fiber reinforced plastic is preferable in terms of corrosion resistance and strength.

The flexible member can take various structures other than the cantilever 15 shown in FIGS. 2 and 3. The cantilever 40 shown in FIG. 5 has a substantially circular tip at the cantilever 15 and a large area for receiving earth and sand. 6 and 7 have a double-supported beam structure, and the double-supported beam 50 is fixed to the case 14 via the pedestal 13 at both ends of a hook-like body having a protrusion 50a protruding substantially at the center. Has been. In this case, FIG. 6 is a plan view, and FIG. 7 is a cross-sectional view taken along line BB in FIG.
The doubly supported beam 50 has a substantially circular central portion, and has a mountain-shaped protrusion 50 a on the detection surface side of the diaphragm 12 in the central portion.
8 and 9 have a diaphragm structure. The diaphragm 60 has a projection 60 a protruding substantially at the center, and the peripheral edge is fixed to the case 14 via the pedestal 13. In this case, FIG. 8 is a plan view, and FIG. 9 is a cross-sectional view taken along the line CC in FIG. By changing the shape and material of beams and diaphragms, it is possible to cope with the types of earth and sand that can be detected.

FIG. 10 is a diagram illustrating an installation example of the sensor element 10.
In the example shown in this figure, the sensor elements 10 are installed vertically and horizontally at regular intervals at the foot of a place where there is a possibility of landslide such as a mountainous area or a steep slope. A range of landslides can be detected by arranging a plurality of sensor elements 10 over a wide range. In addition, the code | symbol 70 in a figure shows a normal groundwater level.
FIG. 11 is a diagram illustrating an example when a landslide occurs. Since all the sensor elements 10 covered with the earth and sand detect the earth and sand, the range of the landslide can be detected by examining the sensor elements 10 at the tip of the discharged earth and sand. In this case, it is necessary to grasp the position information of each sensor element 10 in advance.

In addition, the landslide detection apparatus 1 of this Embodiment can also detect flooding other than earth and sand and an avalanche.
FIG. 12 is a diagram illustrating an example when flooding occurs. In addition, the code | symbol 71 in a figure has shown the change of the groundwater level. Since all the sensor elements 10 in contact with water detect water, it is possible to detect the range of flooding by examining the sensor element 10 at the tip of the flooded part.

The cable 16 connected to each of the plurality of sensor elements 10 is connected to the switch 19 of the landslide detection device 1 installed in the shed 80 at a remote point.
Returning to FIG. 1, the switch 19 has a large number of semiconductor analog switches (or mechanical relay contacts), and switches a plurality of sensor elements 10 according to a switch signal from the control unit 28. A plurality of sensor elements 10 are connected to the switch 19, and the plurality of sensor elements 10 are sequentially switched by sequentially turning on / off the semiconductor analog switch.
The voltage controlled oscillator 20 generates a sinusoidal electric signal whose frequency continuously changes in a predetermined frequency range (for example, 1 kHz to 20 kHz). The amplifier 21 amplifies the sine wave signal generated by the voltage controlled oscillator 20 to a level at which the sensor element 10 can be driven, and outputs the amplified signal as an excitation signal Vr.
The resistor 24 is inserted in series between the amplifier 21 and the sensor element 10, and a voltage corresponding to the current flowing through the sensor element 10 is generated at both ends thereof.
Since the current flowing through the sensor element 10 changes according to the change in frequency, the voltage appearing at both ends of the resistor 24 reflects the frequency characteristics of the sensor element 10.

The differential amplifier 25 amplifies the voltage generated at both ends of the resistor 24 and outputs the amplified voltage. The amplifier 22 amplifies the voltage output from the differential amplifier 25 to a predetermined level and outputs it as a voltage Vi. The 4-quadrant analog multiplier 26 multiplies the excitation signal Vr from the amplifier 21 and the output voltage Vi from the amplifier 22 to remove the influence of noise on these voltages.
The low-pass filter 27 outputs a signal obtained by removing cos (2ωt + α + β), which will be described later, from the output signal of the 4-quadrant analog multiplier 26. The amplifier 23 amplifies the signal that has passed through the low-pass filter 27 to a predetermined level and outputs it as an output signal Vo. This output voltage Vo is a signal reflecting the frequency characteristics of the sensor element 10 with respect to the frequency change of the excitation signal Vr. At this time, if nothing is in contact with the surface of the sensor element 10, that is, if the surrounding is air, as shown in the output voltage waveform diagram (a) of FIG. A voltage with appears. When water contacts the surface of the sensor element 10 from this state, the vibration characteristics of the sensor element 10 change, and the peak voltage position shown in the output voltage waveform diagram (b) of FIG. To change. When earth and sand contact, a clear peak voltage as shown in the output voltage waveform diagram (c) of FIG. 13 cannot be seen. The contact / non-contact of water and earth and sand can be determined from such changes in peak voltage.

  Here, the operation principle will be described using mathematical expressions as follows. Note that Vr = Asin (ωt + α) and Vi = Bsin (ωt + β). However, A and B are amplitudes, ωt is a frequency, and α and β are phase shifts.

Vr × Vi = Asin (ωt + α) × Bsin (ωt + β)
= AB [cos (β-α) -cos (2ωt + α + β)] / 2 (1)

  The part of cos (β−α) in the equation (1) is a direct current component that changes in accordance with the phase difference, and includes the amplitude component of the signal Vi. The cos (2ωt + α + β) portion is a signal having a frequency twice that of the original excitation signal Vr and the signal Vi. Since the required frequency characteristic information is the amplitude (magnitude) of the signal Vi, only cos (β−α) in equation (1) is sufficient. Therefore, the component of cos (2ωt + α + β) may be removed by passing through the low-pass filter 27. In this way, the frequency characteristic appears in the form of voltage in the output Vo. When the sensor element 10 is in contact with the earth and sand, the peak frequency and level change, so that the situation can be detected.

Returning to FIG. 1, the control unit 28 includes a CPU (Central Processing Unit) (not shown), a flash memory storing a program for controlling the CPU, a RAM (Random Access Memory) used in the operation of the CPU, An input / output interface is provided. The flash memory stores position information of each sensor element 10 in addition to the control program. The control unit 28 operates in accordance with the control program, controls the switch 19 to detect the earth and sand with each of the plurality of sensor elements 10, and detects the sensor element 10 that has detected the earth and the position information of the sensor element 10. The included earth and sand detection information is transmitted from the communication unit 29. That is, the control unit 28 controls the switch 19 to sequentially switch the plurality of sensor elements 10, and determines contact / non-contact of earth and sand from the output signal Vo of the amplifier 23 for each sensor element 10. Position information is input to the communication unit 29 as sediment detection information. Judgment of contact / non-contact of the earth and sand is based on the characteristic vibration frequency characteristic when the earth and sand do not contact the sensor element 10 (that is, when the surrounding is air). Note that once the unique vibration frequency characteristics of the sensor element 10 are set, it is not necessary to reset them except during maintenance.
The communication unit 29 performs communication using the public line network, and converts the sediment detection information input from the control unit 28 into a radio signal in a frequency band and radio wave format used for data communication of the public line network. Then send.

FIG. 14 is a diagram illustrating a communication path between the landslide detection device 1 and a user terminal (so-called personal computer) 100. The landslide detection device 1 and the user terminal 100 are connected via a public line network 110. The public line network 110 includes a data communication unit 120, a data management unit 130, and an Internet information providing unit 140 owned by a communication carrier. The data communication unit 120 and the data management unit 130 are connected by a dedicated line 150. Routers 120 a and 130 a are arranged at both ends of the dedicated line 150 connecting the data communication unit 120 and the data management unit 130.
The data communication unit 120 receives the radio signal transmitted from the landslide detection device 1, demodulates the sediment detection information, and transmits it to the data management unit 130. The data management unit 130 includes a router 130a and a center monitoring device 130b, and the center monitoring device 130b converts the sediment detection information sent from the data communication unit 120 into an HTML (HyperText Markup Language) format to the Internet information providing unit 140. Send.

  The Internet information providing unit 140 includes a router 140a and a Web server 140b. The Web server 140b accumulates HTML-format sediment detection information transmitted from the center monitoring apparatus 130b, and is transmitted from a Web browser installed in the user terminal 100. In response to the request, it is provided to the user terminal 100 using a content transmission / reception protocol such as HTTP (Hypertext Transfer Protocol). In the user terminal 100, the installed application visually displays in two dimensions the presence / absence of a landslide in the monitoring location and the landslide range when the landslide occurs based on the sediment detection information. Of course, it is possible to use an intranet other than the Internet.

  The voltage controlled oscillator 20 and the amplifier 21 constitute signal generating means. The switch 11 and the control unit 28 constitute a switching unit. The resistors 22 to 24, the differential amplifier 25, the 4-quadrant analog multiplier 26, the low-pass filter 27, and the control unit 28 constitute detection means. Further, the communication unit 29 and the antenna 30 constitute a communication unit. The user terminal 100 corresponds to a monitoring device.

  In the water level detection device 1 configured as described above, the sine wave signal generated by the voltage controlled oscillator 20 is amplified by the amplifier 21 to be the excitation voltage Vr, and is connected to the device body by the switching unit 15. 10 and 4 quadrant analog multipliers 26 are input to each. When the vibration signal Vr is input to the sensor element 10, mechanical vibration is generated from the sensor element 10. In addition, a voltage corresponding to the current flowing through the sensor element 10 is generated at both ends of the resistor 24. This voltage is amplified by the differential amplifier 25 and then amplified by the amplifier 22 to output the voltage Vi. The voltage Vi from the amplifier 22 and the excitation signal Vr from the amplifier 21 are multiplied by the 4-quadrant analog multiplier 26, and the output of the cos (2ωt + α + β) component is removed by the low-pass filter 27. To obtain an output voltage Vo.

  The output signal Vo is a signal reflecting the frequency characteristics of the sensor element 10 with respect to the frequency change of the excitation signal Vr. If nothing is in contact with the surface of the sensor element 10 at this time, a voltage having a peak at a frequency near the natural frequency of the sensor element 10 appears as shown in the output voltage waveform diagram of FIG. When earth and sand come into contact with the sensor element 10, the vibration characteristics of the sensor element 10 change, and the position and magnitude of the peak voltage change as shown in the output voltage waveform diagram of FIG. The control unit 28 determines contact / non-contact of the sediment from the change in the peak voltage, converts the result into a data format that can be handled by the communication unit 29 as the soil detection information together with the position information of the sensor element 10, and the communication unit 29 to the public line network 110. The control unit 28 performs this process for each of the plurality of sensor elements 10. Thereby, the user terminal 100 can grasp the presence or absence of landslide. Moreover, since the control part 28 performs control which switches the several sensor element 10 one by one repeatedly, it can also grasp | ascertain the range of the landslide in the user terminal 100. FIG.

Thus, according to the landslide detection device 1 of the present embodiment, the piezoelectric ceramic 11, the diaphragm 12 having the piezoelectric ceramic 11 on one surface and the other surface serving as the detection surface, and the diaphragm 12 are supported. A pedestal 13 and a case 14 that supports the diaphragm 12 via the pedestal 13 so that a space is formed around the piezoelectric ceramic 11 provided on the diaphragm 12 and at least the detection surface of the diaphragm 12 is an outer surface; Since the sensor element 10 is provided with a cantilever 15 that is a flexible member that is positioned on the detection surface side of the diaphragm 12 and that protrudes so as to be able to press the detection surface and is elastically supported by the case 14, Detection can be performed with high accuracy. In particular, the protrusion 15a provided on the cantilever 15 greatly contributes to improvement in detection accuracy.
Moreover, since the sensor element 10 using the piezoelectric ceramic 11 can be manufactured at low cost, the apparatus can be provided at low cost. In addition, the sensor element 10 using the piezoelectric ceramics 11 has almost no erroneous detection factors, and can be used without problems even in bad weather such as fog or heavy rain.

  In addition to the cantilever 15 which is a flexible member, it is of course possible to use a doubly-supported beam or a diaphragm, and the same effect as when the cantilever 15 is used can be obtained.

  Moreover, the landslide detection device 1 of the present embodiment has a plurality of sensor elements 10 and installs them in a place such as a mountainous area or a steep slope where a landslide disaster is a concern, thereby reducing the range of landslides. Can be detected.

  Further, the landslide detection apparatus 1 of the present embodiment includes a communication unit 29 that can be connected to a public line network and transmits landslide detection information using the public line network. The range of landslides and landslides can be monitored at.

It is a block diagram which shows schematic structure of the landslide detection apparatus which concerns on one embodiment of this invention. It is a top view which shows the sensor element which the landslide detection apparatus of FIG. 1 has. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. It is AA sectional view taken on the line in FIG. 2 when earth and sand are detected. It is a top view which shows the application example of the sensor element which the landslide detection apparatus of FIG. 1 has. It is a top view which shows the application example of the sensor element which the landslide detection apparatus of FIG. 1 has. FIG. 7 is a cross-sectional view taken along line B-B in FIG. 6. It is a top view which shows the application example of the sensor element which the landslide detection apparatus of FIG. 1 has. It is CC sectional view taken on the line of FIG. It is a figure which shows an example of installation of the sensor element which the landslide detection apparatus of FIG. 1 has. It is a figure which shows an example when a landslide occurs. It is a figure which shows an example when flooding generate | occur | produces. FIG. 2 is a waveform diagram of an output voltage Vo in the landslide detection device of FIG. 1, (a) is a waveform diagram in which air is detected, (b) is a waveform diagram in which water is detected, and (c) is a waveform diagram in which earth and sand are detected. It is a figure which shows the communication path | route between the landslide detection apparatus of FIG. 1, and a user terminal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Landslide detection apparatus 10 Sensor element 11 Piezoelectric ceramics 12 Diaphragm 13 Base 14 Case 15, 40 Cantilever (cantilever)
15a protrusion 50 doubly supported beam 50a protrusion 60 diaphragm 60a protrusion 100 user terminal 110 public network 120 data communication unit 120a, 130a, 140a router 130 data management unit 130b center monitoring device 140 internet information providing unit 140b web server 150 dedicated line

Claims (5)

A plurality of sensor elements, a signal generating means for generating a sine wave signal whose frequency changes over time within a predetermined range, and a sine wave generated by the signal generating means by switching the plurality of sensor elements one by one A switching means for applying a signal, and a change in current flowing through the sensor element to which a sine wave signal is applied each time switching is performed as a change in voltage, and a change in frequency characteristics of the captured voltage waveform In a landslide detection device comprising a detection means for detecting and detecting earth and sand ,
The sensor element is a sensor element that converts electrical energy into mechanical energy, a piezoelectric element, a diaphragm having the piezoelectric element on one surface and the other surface serving as a detection surface, and a piezoelectric element of the diaphragm A case that supports the diaphragm so that the detection surface of the diaphragm becomes an outer surface, and a protrusion that is positioned on the detection surface side of the diaphragm and protrudes so as to press the detection surface landslide detection apparatus, characterized in that the anda flexible member which is elastically supported on the casing with a. 2. The landslide according to claim 1, wherein the flexible member is a cantilever having one end fixed to the case and the other end projecting the protrusion and extending to a substantially central portion of the detection surface. Detection device . The landslide detection device according to claim 1, wherein the flexible member is a doubly-supported beam in which the protrusion protrudes substantially in the center and both ends are fixed to the case. The landslide detection device according to claim 1, wherein the flexible member is a diaphragm in which the protrusion protrudes substantially in the center and a peripheral portion is fixed to the case. Be connectable to the telecommunications line, any one of the preceding claims, characterized in that it comprises a communication means for transmitting the sediment detection information obtained from said detecting means by using the electrical communication line 1 The landslide detection device according to item .

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