JP7483195B2 - Remote condition monitoring system and monitoring method - Google Patents

Description

The present invention relates to a remote condition monitoring system and a monitoring method.

2. Description of the Related Art Conventionally, there has been known a technique for performing preventive maintenance of a structure by measuring predetermined locations of the structure and monitoring the state of the structure.

The following Patent Document 1 discloses a condition monitoring system that has an acceleration sensor installed on a bridge pier that measures acceleration, and an information processing device that evaluates the soundness of the pier based on a vibration waveform obtained by analyzing the acceleration.

The following Patent Document 2 discloses a measurement system having a slave unit provided at a measurement location and a master unit that wirelessly communicates with the slave unit. The slave unit has a sensor that measures physical quantities such as strain, displacement, and acceleration, a wireless communication unit that transmits information on each physical quantity detected by the sensor to the master unit, and a battery that supplies power to the sensor and the transmission means.

The following Patent Document 3 discloses a preventive maintenance monitoring system that includes a plurality of acceleration sensors installed on a structure to detect displacement, a calculation device that evaluates fatigue based on the displacement detected by the acceleration sensors, and a display means that is connected to the calculation device via the Internet and displays the calculation results.

JP 2015-230206 A JP 2008-234361 A JP 2015-98686 A

In conventional remote condition monitoring systems, information indicating the condition of a structure is remotely transmitted using mobile phone lines such as 3G and LTE. Although such conventional mobile phone lines are highly reliable and available, the call charges and communication equipment costs are high. In the case of IoT (Internet of Things), the number of devices that communicate increases, which raises the issue of high communication costs.

Furthermore, since conventional communications via mobile phone lines consume a lot of power, the batteries built into the devices have to be large, which results in a problem of the devices themselves becoming larger.

Recently, low-power wide-area wireless network services have been attracting attention as the next-generation wireless communication standard in the IoT era, and demonstration experiments are being conducted. The low-power wide-area wireless network service is, for example, a service that uses a wireless communication technology called LPWA (Low Power Wide Area). By using the low-power wide-area wireless network service, low-cost, low-power consumption, and long-distance communication are possible. However, this wireless communication service has a problem that it is not possible to transmit all of the conventional structure information showing the state of the structure remotely, since the transmission speed is low and the data size transmitted and received is small.

Furthermore, there was still no satisfactory solution for transmitting data stably in mountainous areas or remote islands where it is difficult to share a power source.

The present invention provides a remote condition monitoring system and a monitoring method that can effectively monitor the condition of a structure from a remote location using a wireless line.

The remote condition monitoring system of the present invention has an information collection unit that is provided in a structure and collects information regarding the state of the structure, and a monitoring unit that is connected to the information collection unit via a communication line and remotely monitors the structure, wherein the information collection unit has a sensor unit that measures data indicating a physical quantity, a data processing unit that processes the data measured by the sensor unit, and a first communication unit that transmits the data processed by the data processing unit to the monitoring unit, and the monitoring unit has a second communication unit that receives data from the information collection unit, a memory unit that stores the data received by the second communication unit, and an information extraction unit that extracts information indicating the state of the structure based on the data stored in the memory unit, wherein the sensor unit includes a strain sensor that measures an amount of strain, the data processing unit extracts the amount of strain at a predetermined time, and the information extraction unit outputs at least one piece of information indicating an abnormal state when the data extracted by the data processing unit deviates by a predetermined amount compared to the distribution of areas of change in the amount of strain in the past.

The remote condition monitoring system of the present invention has a plurality of information collection units that are provided in a structure and collect information regarding the state of the structure, and a monitoring unit that is connected to the information collection units via a communication line and remotely monitors the structure, wherein the information collection unit has a sensor unit that measures an amount of strain, an acceleration sensor unit that measures acceleration, a data processing unit that processes data measured by the sensor unit and the acceleration sensor unit, and a first communication unit that transmits data processed by the data processing unit to the monitoring unit, and the monitoring unit has a second communication unit that receives data from the plurality of information collection units, a memory unit that stores the data received by the second communication unit, and an information extraction unit that extracts information indicating the state of the structure based on the data stored in the memory unit, wherein the sensor unit includes a strain sensor that measures an amount of strain, and the information extraction unit compares data from the strain sensors that measure the amount of strain in the plurality of information collection units, and if a deviation between the data exceeds a predetermined value, outputs at least one of the pieces of information indicating an abnormal state.

According to the remote condition monitoring system and monitoring method of the present invention, the condition of a structure can be monitored remotely and effectively using a wireless line. Even if there is a specific restriction of a wireless communication method, such as a small amount of communication data, data necessary for grasping the condition of the structure can be transmitted to a remote monitoring unit. Furthermore, data can be transmitted stably to the monitoring unit even in remote locations where it is difficult to secure a power source.

In addition, based on the data sent from the information collection unit at a specific time, it is possible to grasp damage or defects in structures, as well as the time leading up to these. This allows for quick response to repairs (post-mortem maintenance), and makes it possible to formulate appropriate repair plans for preventive maintenance to prevent accidents from occurring. It also improves the planning of inspection timing, inspection items, inspection locations, etc., for maintenance (regular maintenance).

1 is a diagram showing a configuration of a remote status monitoring system according to an embodiment of the present invention; FIG. 1 is a flowchart showing the flow of a monitoring method using a remote status monitoring system.

Hereinafter, an embodiment of a remote status monitoring system and a monitoring method will be described with reference to the drawings. However, the present invention is not limited to the following embodiment.

1 is a diagram showing the configuration of a remote condition monitoring system 10. The remote condition monitoring system 10 is a system that remotely monitors the condition of structures (not shown) such as buildings, bridges, tunnels, equipment, ships, utility poles, traffic control facilities, earth structures, roads, piping, and pipelines. This system is used to grasp the condition and progress of aging deterioration of structures, prevent accidents, grasp the condition and extent of damage in the event of an earthquake, disaster, or fire, prevent accidents, preventive maintenance, and draft construction plans. Hereinafter, the remote condition monitoring system 10 will be simply referred to as system 10.

The system 10 includes an information collection unit 12 that is provided in a structure and collects information on the state of the structure, and a monitoring unit 14 that remotely monitors the structure. The information collection unit 12 and the monitoring unit 14 are connected via a communication line 16. The information collection unit 12 is a so-called IoT device, and is installed singly or in multiple units, and transmits measurement data output from various sensors to the monitoring unit 14.

The communication line 16 includes low-power wide-area wireless communication lines such as SIGFOX (registered trademark), LoRa (registered trademark), NB-IoT, NB-Fi Protocol, GreenOFDM, DASH7, RPMA, Wi-SUN, and LTE-MTC (Low Power Wide Area (LPWA)), Bluetooth (registered trademark), Wi-Fi (registered trademark), EnOcean (registered trademark), and ZigBee (registered trademark) are short-distance wireless communication methods, cellular LPWA, and mobile phone lines such as 3G and LTE. For example, SIGFOX has a long transmission distance of several tens of km, a very slow transmission speed of 100 bps (uplink), and data is 12 bytes (uplink), which is less than 1/100 of Ethernet data.

The information collecting unit 12 includes a sensor unit 18 that measures data indicating physical quantities, which includes a strain sensor 28 that measures strain, an acceleration sensor 30 that measures acceleration, and a temperature sensor 32 that measures temperature, a data processing unit 20 that processes the data measured by the sensor unit 18, a first communication unit 22 that transmits the data processed by the data processing unit 20 to the monitoring unit 14, a timer unit 24 with a timing function, and a power supply unit 26 that supplies power to each device in the information collecting unit 12.

The strain sensor 28 is a sensor that measures the amount of strain of the structure, i.e., the physical amount of strain or displacement, and is, for example, a strain gauge. The acceleration sensor 30 is a sensor that measures vibration information of the structure, and is, for example, a single-axis or multi-axis accelerometer that can detect minute vibrations. The temperature sensor 32 is a sensor that measures the temperature of the structure, and is, for example, a thermistor. The sensor unit 18 may include an angle sensor, an acoustic sensor, an ultrasonic sensor, a humidity sensor, a GPS sensor, and a distance sensor, although these are not shown.

The data processing unit 20 processes the data measured by the sensor unit 18 into data that can be used via the communication line 16 and that can grasp the state of the structure. Specifically, the data processing unit 20 extracts the amount of strain, acceleration, and temperature at a given time. If humidity is also measured, the data processing unit 20 also extracts the humidity at the given time.

The first communication unit 22 is a communication interface having a chip on which an application for realizing communication with the communication line 16 is implemented and an antenna. As an example, the communication content when the communication line 16 is SIGFOX will be described. Currently, the amount of data in SIGFOX is up to 12 bytes per time. In this embodiment, each data indicating a physical quantity is 3 bytes for the amount of strain, 2 bytes for the acceleration of one axis, and 2 bytes for the temperature, and including the 5-byte header added during communication, there are a total of 12 bytes. In this case, all data can be transmitted in one communication. In addition, if two-axis acceleration and humidity are further used as data indicating a physical quantity, the amount of data increases by 6 bytes. In this case, all data will be transmitted in two separate communications.

The timer unit 24 can arbitrarily set the above-mentioned predetermined time, and when that time comes, outputs a control signal to the data processing unit 20. The predetermined time may be twice a day, once during the day and once at night, or three or more times a day, or once every few days.

The power supply unit 26 may be a combination of a battery and a power generation function that generates power from external energy, a piezoelectric element that converts vibrations of a structure into power, a heat conversion element that converts heat into power, a removable dry cell, a solar cell, or a dye-sensitized solar cell, as long as it can supply power to the data processing unit 20, the first communication unit 22, and the timer unit 24. The power supply unit 26 is preferably an independent power supply that does not require wiring or charging.

Next, a device for remotely monitoring a structure will be described. The monitoring unit 14 is connected to a terminal (not shown) of a user who uses this system via a wired or wireless communication line, and the user can grasp the state of the structure based on the information output from the monitoring unit 14. The monitoring unit 14 has a second communication unit 34 that receives data from the information collecting unit 12, a storage unit 36 that stores the data received by the second communication unit 34, and an information extraction unit 38 that extracts information indicating the state of the structure based on the data stored in the storage unit 36.

The second communication unit 34, like the first communication unit 22, is a communication interface having a chip on which an application for realizing communication with the communication line 16 is implemented and an antenna, and receives data from the first communication unit 22.

The storage unit 36 is a storage device such as a hard disk drive (HDD) or a solid state drive (SSD). The storage unit 36 stores the above-mentioned various data sent from the information collecting unit 12. If the sensor unit 18 includes a temperature and humidity sensor, humidity data is also stored. The storage unit 36 can store correlation data indicating the correlation between the amount of strain and acceleration from the data sent from the information collecting unit 12. The storage unit 36 can also store the calculation results of the information extracting unit 38, an operating system (OS), various application programs, and the like.

The information extraction unit 38 performs calculations on the various data stored in the storage unit 36 and outputs information indicating the state of the structure. The information extraction unit 38 can also directly use data sent from the information collection unit 12 in its calculations.

When the amount of strain exceeds a predetermined value, the information extraction unit 38 outputs at least one of the amount of strain or information indicating an abnormal state. The predetermined value is an amount of strain that causes defects such as cracks in the area where the information collection unit 12 is installed. The information indicating the abnormal state is information that can be recognized by the user, such as text information. This makes it possible to remotely grasp that a defect has occurred. Furthermore, when the degree of progress of damage in the above-mentioned area is known from past data, it is also possible to set the amount of strain before the damage occurred as the predetermined value. This makes it possible to prevent accidents from occurring.

The information extracting unit 38 can also calculate the amount of displacement based on the amount of strain and the gauge length of the strain sensor 28 stored in the memory unit 36. If the amount of displacement exceeds a predetermined value, the information extracting unit 38 can also output at least one of the amount of displacement and information indicating an abnormal state. In this case, the predetermined value is an amount of displacement that would cause a defect such as a crack at the location where the information collecting unit 12 is provided. The amount of displacement is stored in the memory unit 36 and can be used as an alternative parameter for the amount of strain.

The information extraction unit 38 can also calculate an approximation curve based on the past strain amounts stored in the storage unit 36, and calculate the time when the predetermined value will be reached from the curve. By understanding the degree of damage and the time of damage, a repair plan can be made with ample time to spare, without being excessive or lacking.

Furthermore, the information extraction unit 38 maps the correlation between the amount of strain and temperature, the correlation between the amount of strain and humidity, the correlation between the amount of strain and temperature and humidity, and the correlation between the amount of strain and acceleration at a given time, and stores them in the storage unit 36. This operation is performed every time new data is sent from the information collection unit 12, and each mapping is overwritten.

Then, when the strain amount and temperature sent from the information collecting unit 12 have a predetermined deviation compared to the correlation between the strain amount and temperature in the past, the information extracting unit 38 outputs at least one of the information indicating the correlation or the abnormal state. The information indicating the correlation is a table, a graph, etc. The strain amount usually changes according to the temperature change on a daily or seasonal basis. In addition, due to the aging of the structure, the amount of change in the strain amount or the trajectory of the change differs from that of the past, or the distribution of the area of change in the strain amount differs from that of the past. Such a difference is treated as a predetermined deviation when a threshold or area is set on the mapping of the correlation, and when the latest data exceeds the set predetermined value, it is output by the information extracting unit 38 as information indicating an abnormal state. The predetermined value as the predetermined deviation is specific to the structure, so that it can be arbitrarily set by analyzing the data leading up to the damage during operation. This makes it possible to grasp from a remote location that the structure has been damaged or that there is a risk of damage. In addition, humidity, or temperature and humidity, can be used instead of temperature, which is one of the parameters of the correlation. This is because the amount of strain usually changes according to daily or seasonal changes in humidity or temperature and humidity. When there is a predetermined deviation from the past correlation between the amount of strain and humidity, or the past correlation between the amount of strain and temperature and humidity, the information extraction unit 38 outputs at least one of the information indicating the correlation or an abnormal state. The method of setting the threshold or area on the correlation mapping and the method of outputting the information indicating an abnormal state are the same as when the parameter is temperature. This makes it possible to remotely grasp that a structure has been damaged or that there is a risk of damage.

In addition, when the strain amount and acceleration sent from the information collecting unit 12 have a predetermined deviation compared to the correlation between the past strain amount and acceleration, the information extracting unit 38 outputs information indicating the correlation or an abnormal state. The data indicating the correlation is a table, a graph, etc., and the data (hereinafter referred to as correlation data) is stored in the storage unit 36. The strain amount and acceleration have a certain correlation, and the strain amount tends to increase when the acceleration is large. When the structure deteriorates with age, the relationship between the strain amount and acceleration is plotted in a region different from the region of the past correlation. A threshold or a boundary line is set on the outer edge of the region of the past correlation, and when the latest correlation data exceeds the set predetermined value, it is treated as a predetermined deviation, and the information extracting unit outputs information indicating an abnormal state. The predetermined value as the predetermined deviation is specific to the structure, so it can be arbitrarily set by analyzing the correlation data up to the time of damage during operation. This makes it possible to remotely grasp that the structure has been damaged or that there is a risk of damage.

The information extraction unit 38 can also compare the correlation data in the multiple information collection units 12, and when the deviation between the correlation data exceeds a predetermined value, output at least one of the correlation data or information indicating an abnormal state. The correlation data described in the previous paragraph is related to the amount of strain and acceleration measured by the same information collection unit 12, and the information extraction unit 38 compares this correlation data with the same data in the past to extract the deviation state. On the other hand, the information extraction unit 38 can also compare the correlation data in each information collection unit 12, and extract the deviation state. The correlation data in each information collection unit 12 also has a certain correlation, and when the structure deteriorates with age, the deviation between the correlation data changes. When this deviation exceeds a predetermined value, the information extraction unit 38 outputs information indicating an abnormal state. The predetermined value as the predetermined deviation is specific to the structure, so it can be arbitrarily set by analyzing data leading up to the damage during operation. This makes it possible to grasp the damage state of the structure remotely, or to estimate future damage.

Specifically, the data processing unit 20 detects the occurrence of an earthquake when the measured acceleration is equal to or greater than a predetermined value, processes the measurement data at the time of detection, and transmits the data to the monitoring unit 14 .

Furthermore, the data processing unit 20 detects the occurrence of a fire when the measured temperature is equal to or higher than a predetermined value, processes the measurement data at the time of detection, and transmits the data to the monitoring unit 14. In these aspects, the timer unit 24 may be operated in response to the detection of a disaster as a trigger, and detailed data may be periodically transmitted to the monitoring unit 14 as measurement data at short intervals from normal times.

One of the characteristic principles of the present invention is to utilize the relationship between stress and strain (deformation) when a structure (solid material) is subjected to an external force, and to compare the mechanical properties of the structure with the amount of change due to temperature, humidity, environment, etc., by quantifying them. Deterioration of a structure generally progresses due to external forces, chemical reactions, creep, heat, etc. Therefore, the amount of change in the deterioration state, that is, the amount of change, is continuously monitored by utilizing the laws of physics. In this way, it is expected that the method will be used for various purposes, such as analyzing and interpreting huge amounts of data over a long period of time to grasp or estimate the state of damage.

The structure may be concrete, plastic, or metal. For structures that are subject to external forces such as vibration, correlation data between the amount of strain and an acceleration sensor is used, and for structures that are left stationary, correlation data between the amount of strain and temperature or humidity is used to improve accuracy. If the surface of the structure is covered with a coating agent, the strain sensor 28 is attached to the structure via an adhesive after the coating agent is removed.

Next, one embodiment of a remote status monitoring method using the system 10 will be described with reference to FIG.

First, in step S01, the sensor unit 18 provided in the structure measures data indicating physical quantities. Specifically, the strain sensor 28 measures the amount of strain, the acceleration sensor 30 measures the acceleration, and the temperature sensor 32 measures the temperature.

In step S02, the data processing unit 20 processes the measured data. Specifically, the data processing unit 20 extracts the amount of strain, acceleration, and temperature at a predetermined time.

Then, in step S03, the first communication unit 22 transmits the processed data to the remote monitoring unit 14, and in step S04, the second communication unit 34 in the monitoring unit 14 receives the transmitted data. Then, in step S05, the storage unit 36 stores the received data.

Finally, in step S06, the information extraction unit 38 extracts information indicating the state of the structure based on the data stored in the storage unit 36. Specifically, when the amount of strain exceeds a predetermined value, information indicating the amount of strain or an abnormal state is output.

The present invention is not limited to the configuration shown in FIG. 1 as long as the system 10 has a function capable of executing the above-mentioned monitoring method. The above series of steps can be executed by hardware or software. Furthermore, one functional block may be configured by hardware alone, software alone, or a combination of these. Furthermore, the monitoring unit 14 of this embodiment is not limited to the above configuration, and at least some of the functions may be operated by an application installed on the user's terminal.

It is also possible to extract the maximum value of acceleration in a time period of several minutes including a specified time. If the acceleration sensor 30 has three detection axes, the measurement values are extracted for each axis. In this case, the amount of communication data increases, so the first communication unit 22 transmits the data in multiple parts. This allows the monitoring unit 14 to grasp the state of the structure in more detail.

Furthermore, the data processing unit 20 can calculate the natural frequency of the structure based on the measured acceleration and transmit the data to the monitoring unit 14. The monitoring unit 14 can detect an abnormal state of the structure based on a change in the natural frequency caused by deterioration over time or damage to the structure.

In the present embodiment, a configuration may be adopted in which two-way communication is possible between the first communication unit 22 and the second communication unit 34. With this configuration, the processing contents of the data processing unit 20 can be changed from the monitoring unit 14. In addition, the monitoring unit 14 can also set a predetermined time in the timer unit 24.

In this embodiment, the user can view or download the necessary information or history by accessing the monitoring unit 14. This allows the user to grasp the deterioration tendency of the structure's condition even before the structure reaches an abnormal state.

REFERENCE SIGNS LIST 10 Remote status monitoring system, 12 Information collection unit, 14 Monitoring unit, 16 Communication line, 18 Sensor unit, 20 Data processing unit, 22 First communication unit, 24 Timer unit, 26 Power supply unit, 28 Strain sensor, 30 Acceleration sensor, 32 Temperature and humidity sensor, 34 Second communication unit, 36 Memory unit, 38 Information extraction unit.

Claims (3)

A plurality of information collecting units provided in the structure for collecting information on the state of the structure;
a monitoring unit that is connected to the information collecting unit via a communication line and remotely monitors a structure;
In a remote condition monitoring system having
The information collecting unit,
A sensor unit that measures the amount of strain;
a data processing unit that processes data measured by the sensor unit;
a first communication unit that transmits data processed by the data processing unit to the monitoring unit;
having
The monitoring unit is
A second communication unit that receives data from the information collecting unit;
A storage unit that stores data received by the second communication unit;
an information extraction unit that extracts information indicating a state of a structure based on the data stored in the storage unit;
having
the sensor unit includes a strain sensor that measures a strain amount and an acceleration sensor that measures an acceleration ,
the information extraction unit compares the correlation data from the plurality of information collection units, and when a deviation between the correlation data exceeds a predetermined value, outputs at least one of the correlation data or information indicating an abnormal state;
The correlation data relates to the strain amount and the acceleration, and the information extraction unit compares the correlation data in the multiple information collection units with past correlation data to extract a deviation state.
A remote condition monitoring system comprising: The information collecting unit has a humidity sensor unit that measures humidity.
2. The remote condition monitoring system according to claim 1. The information collecting unit has a temperature sensor unit that measures temperature.
2. The remote condition monitoring system according to claim 1.

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