JPH09243412A - Object-monitoring system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constitute a monitoring system so as to prevent disasters by falling rocks, landslides, which detects a minute movement of an object to be monitored as a precursor of the disaster, predicts danger and quickly sends the information to stations concerned. SOLUTION: A technique for measuring a phase difference of ultrasonic waves is adopted thereby to measure a positional shift highly accurately. A small ultrasonic transmitter 2 is fixed to an object 1 to be monitored and ultrasonic signals from the transmitter 2 are received by an ultrasonic receiver 3 set at an observation point. Transmitting signals and receiving signals are transmitted via a signal cable or radio to a signal-processing circuit 6, where phases are compared. Data are sent to a data-processing device 7 and analyzed, and the result is stored in a memory device. This series of operations are automatically carried out, by a computer. In other words, the system can be used as an unmanned monitoring system. Measurements for the monitoring are executed automatically with a constant cycle. Data are not only sequentially stored in the memory device, but, compared with previous data. Comparison results are also stored in the memory device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monitoring system for monitoring and predicting rockfalls, landslides, and the like, and more particularly to a monitoring system for monitoring an object such as a rock or a protective wall using ultrasonic waves. Regarding

[0002]

2. Description of the Related Art Conventionally, visual observation has been the main method for monitoring for preventive maintenance, which is carried out to protect railways and roads from falling rocks and landslides. In other words, it is a method of visually detecting an abnormality. As a known technique close to this, there is JP-A-56-157862 (natural disaster detection device),
This is to monitor a place where a disaster may occur from a remote place with an optical system and detect a rock fall, a landslide, etc. as an output signal of the linear stripe photoelectric device.

Further, another known technique, Japanese Patent Laid-Open No. 03-21211.
700 (automatic landslide monitoring device) automatically detects landslides using a television camera or other image processing device, and sends an alarm signal and image data to a central device at a remote location, thereby enabling local It enables 24-hour monitoring without humans.

There is also a method of tensioning the wire and monitoring the tension of the wire to detect the occurrence of an abnormality. JP-A-48-4
5007 (a device for predicting the occurrence of rockfall accidents due to a bag body) is a technique for predicting the occurrence of rockfalls, landslides, and the like by utilizing the internal pressure change of the bag body that occurs when a rockfall collides with the bag body.

[0005] All of these known techniques sense relatively large changes in the initial stage when the abnormality occurs, rather than predicting rockfalls and landslides. There is a fear of not. That is, it is impossible to monitor and detect minute changes. In addition, the device is complicated and the price is high. For example, in order to monitor many dangerous places in Japan, enormous cost is required.

Further, as a known technique for monitoring a minute fluctuation in mm level, there is a distance measuring device using a laser technique. In this technology, a reflecting mirror that reflects the laser is installed on the object to be monitored, the laser is emitted from the monitoring observation point toward this reflecting mirror, the reflected laser light is received, and the distance is measured from the time difference from the emitting laser. Therefore, extremely high precision measurement is possible. However, this device is expensive,
There are drawbacks such as being easily affected by fog. With this, it is impossible in terms of cost to constantly monitor all the dangerous points in the country.

There is an aerial ultrasonic technology as a distance measuring device, but this distance measuring method emits ultrasonic waves toward an object,
It receives reflected sound from an object, measures the time difference between transmission and reception, and calculates the distance from it. The transmitted ultrasonic waves naturally use beamforming technology to enhance the directivity, but there is a limit to narrowing the beam angle, and the measurement error due to unevenness of the object surface within the minimum beam angle is considerably large. It is impossible to obtain mm level accuracy. Also, in order to increase the accuracy, the thinner the beam, the inversely proportionally the ultrasonic transmitter becomes huge,
There are drawbacks such as high prices.

[0008]

In order to protect railways and roads from disasters such as rockfalls and landslides, it is very important to monitor the occurrence of abnormalities and to investigate and monitor for preventive maintenance. This applies not only to railways and roads, but also to other general dangerous areas. The problem to be solved by the present invention is to catch these abnormalities in advance, and to notify the relevant persons of the risk prediction information as soon as possible. Highly accurate position fluctuation measurement (mm level) is required to catch minute movements that occur as a precursor to a disaster when abnormal objects (rocks, protection walls, etc.) move abnormally. In Japan, the number of objects that need to be monitored is very large, and the number of measurement points is large, so these need to be constructed at low cost. Needless to say, it should be an unattended detection system. Abnormality occurs suddenly, so
Monitoring needs to be carried out at all times, and further, when more dangers are expected, such as earthquakes, floods, volcanic eruptions, train passages, and blasts, it is necessary to increase the monitoring density. Weather, especially rainfall, snowfall, fog, temperature,
It is necessary to always measure without being influenced by humidity and atmospheric pressure. It is necessary to have a system that is excellent in maintainability because it requires long-term measurement and there are many measurement points. It is necessary to analyze the obtained data promptly and, when an abnormality is predicted, to inform and notify the relevant departments of the information promptly.

A first object of the present patent is to provide a technique for solving some or more of these problems, to provide a highly accurate measuring means at a low price, and unattended, It is to provide a monitoring system that constantly measures.
The second object of the present invention is to
It is an object of the present invention to provide a system that can increase the monitoring density and can perform monitoring without being affected by the weather. A third object of the present invention is to
It is to provide a system capable of quick data processing and notifying the relevant departments of the notification.

[0010]

[MEANS FOR SOLVING THE PROBLEMS] An ultrasonic transmitter for generating an ultrasonic wave having a frequency of 1 kHz to 500 kHz is fixed on the surface of an object to be monitored, and is relatively separated from the ground by a fixed distance. The ultrasonic wave receiver is installed at one or more stable locations, and the ultrasonic wave is received, and the change in the phase difference is monitored with the signal processing unit that detects the phase difference between the transmitted ultrasonic wave and the received ultrasonic wave. A processing device including a data processing unit is provided, and the processing device measures the phase difference change data.
An object monitoring system, which records and transfers change data to a centralized monitoring center via a relay device.

The present invention proposes a method of measuring the position variation with high accuracy by adopting the technique of measuring the phase difference of ultrasonic waves. A small ultrasonic transmitter is fixedly installed on the monitored object, and this ultrasonic signal is received by the ultrasonic receiver placed at the observation point. The number of observation points is one or more. Here, the technical point of the present invention is to place the ultrasonic transmitter and the ultrasonic receiver at different positions. By obtaining the phase difference between the transmitted signal and the received signal, the change in the distance between the transmitter and the receiver can be obtained with high accuracy. Although the absolute distance between the two cannot be obtained, when the distance changes, the phase difference changes before and after the change. By utilizing this feature, highly accurate distance fluctuation (mm level) can be measured with a simple configuration. Since this configuration is simple, it is possible to inexpensively make the system.

The transmission signal and the reception signal are transmitted by a signal cable or wirelessly to a signal processing circuit for phase comparison, sent to a data processing device, data analyzed, and the result is stored in a storage device. It These series of operations are
It is done automatically by the computer. That is, it can be operated as an unmanned monitoring system.

The measurement for monitoring is automatically carried out at regular intervals, and the data is stored one by one in the storage device and compared with the previous data. The comparison result is also stored in the storage device.

Further, the system of the present invention is provided with means for automatically and densely monitoring and measuring in synchronization with a natural disaster such as an earthquake, heavy rain, water damage, volcanic eruption and the like. Further, it is possible to detect the vibration when a train has passed or when a blast work is performed in the vicinity, and perform monitoring measurement in synchronization with the vibration.

When this system is applied to a railway, the approach of a train is detected, monitoring measurement is started, the phase error is measured, and if the value exceeds a preset dangerous value, the train is immediately trained. To stop. After that, the measurement is continued, and the subsequent train operation is judged based on the fluctuation of the phase difference data.

Ultrasonic sound velocity is the temperature, humidity, atmospheric pressure, wind speed,
It is slightly affected by such weather conditions. As a measure against this error occurrence problem, the system of the present invention is provided with means for measuring these meteorological data and correcting the sonic velocity one by one. In addition, since ultrasonic waves are not affected by fog, clouds, rainfall, or snowfall, highly accurate measurement can be performed in any weather condition.

The data stored in the storage device is transmitted to the centralized monitoring center by the telemetering system one by one. The centralized monitoring center is equipped with a means for analyzing the collected data and sending an alarm signal or the like to the relevant departments if necessary. For example, it is possible to stop a train or an automobile approaching the danger prediction area.

There is no limitation in principle in selecting the frequency of the ultrasonic wave used for measurement, but it is restricted from a practical point of view. 20 kHz to 50 kHz is the most suitable frequency band, but it is also practicable at 1 kHz to 500 kHz.

The system is provided with means for automatically diagnosing a failure in the system such as a failure of a measuring instrument. The information is used to prevent false alarms due to the failure and to minimize the monitoring downtime. Can be done.

Further, by combining the laser technology, the measurement accuracy can be improved. in this case,
By monitoring the change in both the ultrasonic phase difference measurement data and the laser distance measurement data, it is possible to measure the position variation of the monitored object with higher accuracy and suppress the occurrence of false alarms.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A concrete embodiment is shown in FIG. This case is an example of a rockfall monitoring system on a railway.
In FIG. 1, an ultrasonic wave transmitter 2 is placed on a rock 1 to be monitored for rockfall.
Fixedly installed. The ultrasonic receivers 3 and 4 are installed on stable ground. The transmitted ultrasonic wave and the received ultrasonic wave signals are converted into electric signals and transmitted to the processing device 5 through a signal cable or the like. In the signal processing device 6 of the processing device 5, first, the phases of the transmission signal and the reception signal are compared, and the phase difference data is acquired. This data is stored in the storage device by the data processing device 7. In addition, the acquired data is compared and verified with past data stored in the storage device, and changes are monitored. These data are transmitted to the centralized monitoring center via the transmission line 8 by the telemetering system.

FIG. 2 shows a functional block diagram of the embodiment shown in FIG. The ultrasonic transmitter is composed of an electronic circuit section 201 and a transmitting element 202. Transmission signal is signal cable 20
3 to the signal processing device 6. Transmitting element 202
The ultrasonic waves emitted by the receiving elements 302 and 402 are received. The receiving elements 302 and 402 are combined with the electronic circuit units 301 and 401, respectively, and combined with the ultrasonic receivers 3 and 4.
Is configured. The signal processor 6 detects the phase difference. The phase difference data includes distance information between the transmitter 2 and the receivers 3 and 4, and when these distances change, the phase difference data changes and the movement of the monitored object is measured. FIG.
Add an explanation. FIG. 3 shows a signal waveform 1 of the oscillator 2.
2, signal waveform 13 of receiver 3, signal waveform 14 of receiver 4
Is schematically shown. Based on the transmission signal 12, the relative phases of the reception signals 13 and 14 are θ1 and θ2.
This value changes as the distance between the transmitter and the receiver changes. For example, when the ultrasonic frequency is 20 kHz, the wavelength is about 17 mm, so the distance between the transmitter and receiver is 1 m.
A change of m results in a phase change of about 21 °.
It can be easily identified by an electronic circuit. Therefore, it is possible to detect the distance variation with extremely high accuracy. The speed of sound of ultrasonic waves is somewhat affected by temperature, humidity, atmospheric pressure, and wind force. In the system of the present invention, these meteorological data are measured by the meteorological data measuring device 9, this data is transmitted to the signal processing device, and the sound velocity value is corrected using this measured data. In addition, the system of the present invention,
The vibration sensing device 10 includes means for detecting ground vibration such as an earthquake or approach of a train, and synchronizing with the ground vibration to strengthen the monitoring measurement density.

The detection data is processed by the data processor 7 and recorded. The processed data is sent to the centralized monitoring center 11 via the transmission line 8 by the telemetering system.

FIG. 4 shows an example of a concrete structure of the ultrasonic transmitter, and FIG.
Shows an example of the circuit diagram. Electronic circuit 201 for ultrasonic transmitter
Thus, a voltage oscillating at the transmission frequency is applied to the ultrasonic transmission element 202. A piezoelectric material such as a piezoelectric ceramic is used for the ultrasonic wave transmitting element 202. The ultrasonic wave transmitting element to which an alternating voltage is applied emits ultrasonic waves of that frequency. In FIG. 4, a solar cell 209 is mounted and supplies electric power. Of course, this can be replaced with a small battery, and power can be supplied from another system. In FIG. 5, the transmission current is the transformer 206.
Is sent to the AD conversion circuit 205, where the phase information of the signal is converted into a digital signal and sent to the signal processing device by the signal cable 203. However, the form of the transmission signal can take various forms, and there are a method of directly sending an analog signal and a method of sending the amplitude information by digitizing it.

A power switch circuit 207 is provided to save power. A command to start monitoring and measurement from the processing device is sent via the signal cable 203 to the power switch circuit 207.
Is sent to and the power is turned on.

FIG. 6 shows an example of a concrete structure of the ultrasonic receiver, and FIG.
Shows an example of the circuit diagram. In FIG. 6, the ultrasonic wave receiving element 302 converts ultrasonic sound pressure into an electric signal. For this element 303, a piezoelectric material such as a piezoelectric ceramic is used. The reception signal is amplified by the amplification circuit 305, the phase information of the signal is converted into a digital signal by the AD conversion circuit 306, and the digital signal is sent to the signal processing device by the signal cable 303. The form of this transmission signal can take various forms like the ultrasonic transmitter.

The receiver also has a power switch circuit 307, which receives a monitoring measurement start command from the processor via a signal cable and turns on the power.

FIG. 8 shows a concrete configuration diagram of the processing system. The meteorological data measuring device 9 includes a temperature gauge 901 and a barometer 9
02, hygrometer 903, wind direction anemometer 904, rain gauge 905
The data logger 1 of the processing device 5 is equipped with sensors such as
Send to 5. The vibration sensing device 10 arranges the data of the vibrometer 1001 by the data converter 1002, and the data logger 15
Send to

Each signal data transmitted by the transmitting ultrasonic signal cable 203 and the receiving ultrasonic signal cables 303 and 403 is input to the phase difference calculating circuit 16 of the signal processing device. Here, the phase difference for each received signal is calculated. This data is input to the next correction calculation circuit 17. This data is corrected and calculated based on the weather data from the data logger 15. The corrected data is sent to the CPU 18 of the data processing device 7. The CPU 18 stores this data in the storage device 19 and also compares and analyzes the data group stored in the past and the latest data.

That is, the change in data is monitored here. The change data is also stored in the storage device 19. These data are transmitted from the telemetering terminal device 20 to the centralized center by the telephone line 8 or the like.

The monitoring / measurement start command is C of the data processing device 7.
It is sent from the PU 18 to each device via the signal line 701. The monitoring and measurement schedule is created by the CPU 18. Usually, regular observations are performed by a predetermined program. When an earthquake is detected by the vibration sensing device, the information is sent to the CPU 18 via the data logger. Upon receiving this information, the CPU immediately sends a command to start monitoring and measurement, and the measurement is started. This emergency measurement mode can be set so that the vibrometer can detect vibrations such as train passing and blasting as well as during an earthquake. Further, the CPU 18 issues an emergency measurement mode even when abnormal weather or wind force is detected by the meteorological data measuring device.

Further, when the approach of the train is detected, the monitoring measurement is started, the phase difference is measured, and if the measured value exceeds a predetermined value, the train is stopped urgently and the monitoring measurement is continued thereafter. It is also possible to continue, measure the change in the phase difference data, and judge the train operation from the result.

System fault information such as a fault of a measuring instrument is transmitted via the signal cable 2101 to the fault monitoring device 2
1 is collected and sent to the CPU 18. CPU than this
18 automatically makes a failure diagnosis. This result is also sent to the centralized monitoring center via the telemetering terminal device 20.

At the central concentration center, the data sent from each observation point is analyzed to predict the danger. With respect to the danger forecast area, an alarm is issued to the relevant departments, for example, the operation of the train is urgently stopped or the road is blocked.

FIG. 9 is a functional block diagram of another configuration example in which signal cables are eliminated and signal information is exchanged wirelessly. An ultrasonic wave transmission signal is an electromagnetic wave in the ultrasonic wave transmitter electronic circuit section 201. Transmitted antenna 2 converted to
10 is received, and is received by the receiving antenna 601 connected to the signal processing device 6. Similarly, the received ultrasonic signal is also converted into an electromagnetic wave, transmitted from the transmitting antennas 310 and 410, and received by the receiving antenna 601. Since the signal cables from the ultrasonic transmitter 2 and the receivers 3 and 4 are unnecessary, the installation becomes easy.

It is important to select the frequency of ultrasonic waves used for monitoring and measurement. FIG. 10 shows the measurement distance resolution of this system with respect to the frequency value. The measurement range resolution depends on the phase difference discrimination resolution of the electronic circuit, but usually 5 ° to 10 °.
Can be achieved relatively easily. From this, in order to obtain a measurement distance resolution of 1 mm or less, it is necessary to select a frequency of 4.7 kHz or more or 9.4 kHz or more.
FIG. 11 shows the limit of the change distance that can be measured with high accuracy.
This is because changes longer than the wavelength cannot be measured. For example, if the confirmation of the maximum distance change of up to 5 mm is required, the frequency must be selected to be 68 kHz or lower. FIG. 12 shows absorption of sound in the air. This permissible value is arbitrarily determined according to the size of the ultrasonic wave transmission level, the measurement distance, the receiver sensitivity, etc.
It is desirable to set it to 0 kHz or less. FIG. 13 shows the strength of sound that can be heard by human beings in correspondence with frequencies. It is desirable to select a frequency so that the inhabitants of the neighborhood do not hear the monitoring measurement sound. From this viewpoint, 20 kHz or more is preferable. From the above consideration, it is most suitable to select the frequency of the ultrasonic wave used for observation and measurement from 20 kHz to 50 kHz. However, by relaxing various conditions and making full use of circuit technology, in principle, 1 kHz to 500 kHz
Realization in the range of z is possible.

In the present invention, the ultrasonic wave may be either a continuous wave which continues continuously or a pulse wave which is emitted intermittently for a fixed time.

Although the technique of the present invention has been described with reference to a rockfall monitoring system for a railway according to FIG. 1, the same is true for other similar purposes, such as a road rockfall monitoring system and a landslide monitoring system. Can be applied as

[0039]

By the technique provided by the present invention, it is possible to realize an extremely simple and low-priced rockfall / landslide monitoring system. Since the technique used for monitoring and measuring can measure the movement change (mm level) of the monitored object with extremely high accuracy, it is possible to predict by catching a slight sign of a rock fall or a landslide. Therefore, it is possible to realize disaster monitoring of a large number of dangerous places without enormous cost.

Since the system of the present invention is capable of automatic measurement, it is possible to continue unattended monitoring for 24 hours.

From the meteorological data measurement values of temperature, humidity, atmospheric pressure, wind force, etc., it is possible to correct the calculation of sound velocity and measure the change of distance with extremely high accuracy, which does not depend on the weather. It is hardly affected by fog or clouds. That is, high-quality monitoring and measurement can be performed without depending on the weather.

The system of the present invention can automatically increase the density of monitoring and measurement when the risk of disasters such as earthquakes and heavy rains is high, and it is possible to closely monitor the grain.

When used as a railway disaster prevention system, when an abnormality is detected by observing in conjunction with the approach of a train and the abnormality is detected, the train is immediately stopped and the monitoring and measurement are continued.
It is possible to have a system that determines the train's subsequent operation plan.

[Brief description of drawings]

FIG. 1 is a configuration explanatory view of a railway rockfall monitoring system according to an embodiment of the present invention.

FIG. 2 is a functional block diagram of FIG. 1 showing an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a relationship between a transmitted ultrasonic signal and a received ultrasonic signal.

FIG. 4 is a structural diagram of an ultrasonic transmitter according to an embodiment of the present invention.

FIG. 5 is a circuit diagram of an ultrasonic transmitter according to an embodiment of the present invention.

FIG. 6 is a structural diagram of an ultrasonic receiver according to an embodiment of the present invention.

FIG. 7 is a circuit diagram of an ultrasonic receiver according to an embodiment of the present invention.

FIG. 8 is a functional block diagram of a processing device according to an embodiment of the present invention.

FIG. 9 is a functional block diagram of another embodiment of the present invention.

FIG. 10 is a graph showing the resolution of measurement distance with respect to ultrasonic frequency.

FIG. 11 is a diagram showing the maximum measurement distance that can be measured with high accuracy with respect to the ultrasonic frequency.

FIG. 12 is a diagram showing absorption of sound in the air with respect to ultrasonic frequencies.

FIG. 13 is a diagram showing the level of human audible sound with respect to ultrasonic frequency.

[Explanation of symbols]

 1: Object to be monitored 2: Ultrasonic wave transmitter 201: Ultrasonic wave transmitter electronic circuit 202: Ultrasonic wave transmitter element 203: Cable for transmitting ultrasonic wave signal 204: Ultrasonic wave transmitter casing 205: Analog / digital converter 206: Transformer 207: Power Switch 209: Solar Cell 210: Radio Antenna 3, 4: Ultrasonic Receiver 301, 401: Electronic Circuit for Ultrasonic Receiver 302, 402: Ultrasonic Receiver Element 303, 403: For Received Ultrasonic Signal Cable 304: Ultrasonic transmitter housing 305: Amplifier 306: Analog / digital converter 307: Power switch 310, 410: Wireless antenna 5: Processing device 6: Signal processing device 601: Wireless antenna 7: Data processing device 701: Signal line for monitoring measurement start command 8: Transmission cable 9: Meteorological data measuring device 901: Temperature gauge 90 2: Barometer 903: Hygrometer 904: Wind direction anemometer 905: Rain gauge 906: Data converter 10: Vibration sensing device 1001: Vibrometer 1002: Data converter 11: Central monitoring center 15: Data logger 16: Phase difference Calculation circuit 17: Correction calculation circuit 18: CPU 19: Storage device 20: Telemetering terminal device 21: Fault monitoring device 2101: Fault monitoring signal cable

Claims (7)

[Claims] 1. A frequency 1 is provided on the surface of an object to be monitored.
An ultrasonic wave generator that generates an ultrasonic wave of kHz to 500 kHz is fixed, and an ultrasonic wave receiver is installed at a relatively stable ground location or a plurality of locations that are separated from the ultrasonic wave source by a certain distance. A processing unit including a signal processing unit that receives a sound wave and detects a phase difference between the transmitted ultrasonic wave and the received ultrasonic wave and a data processing unit that monitors a change in the phase difference is provided. Measure and record,
An object monitoring system, wherein change data is transferred to a centralized monitoring center via a relay device. 2. The centralized monitoring center analyzes and analyzes the change data of the phase difference between the transmitted ultrasonic wave and the received ultrasonic wave for each monitoring point, predicts the danger, and notifies the relevant departments in the danger prediction area. The object monitoring system according to claim 1, wherein an alarm is issued to notify the emergency information. 3. An ultrasonic wave is generated from the ultrasonic transmitter in synchronization with the transmitted ultrasonic wave, an electromagnetic wave is generated from the ultrasonic receiver in synchronization with the received ultrasonic wave, and these electromagnetic waves are received by a wireless antenna. The object monitoring system according to claim 1 or 2, wherein phase difference data between the transmitted ultrasonic wave and the received ultrasonic wave is acquired by the processing device. 4. When the approach of a train is detected, the detection of the phase difference is started, and when the value of the change data of the phase difference exceeds a predetermined value and there is a danger judgment, the train is immediately stopped. A control unit is provided, and
The object monitoring system according to any one of 2 and 3. 5. The object according to claim 1, further comprising a control unit for starting the detection of the phase difference when an earthquake or other ground vibration is detected. Object monitoring system. 6. A measuring unit for measuring meteorological data such as temperature, humidity, atmospheric pressure, wind force and the like, and a calculating unit for calculating the phase difference by correcting the sound velocity by the data of the measuring unit. Item 1. The object monitoring system according to any one of items 1, 2, 3, 4, and 5. 7. The waveform of the ultrasonic wave is a continuous wave or a pulse wave intermittently continuing for a fixed time, as claimed in any one of claims 1, 2, 3, 4, 5, and 6. The object monitoring system according to.