JP5116034B2 - Vibration measurement system, sensor node and management node - Google Patents

Description

  The present invention relates to a vibration measurement system, a sensor node, and a management node for measuring vibration of a measurement object such as a building.

Conventionally, seismic observation and structural health monitoring that installs sensor nodes for detecting vibrations such as acceleration sensors on objects to be measured such as buildings and analyzes vibrations of objects to be measured due to earthquakes based on information from the sensors. Has been done. As shown in Non-Patent Documents 1 and 2, in such a system, data is collected from the sensor node by wireless communication.
Tomomoto Ichikawa and Akira Mita, “Study on Applicability of Wireless Sensors to Structural Health Monitoring”, Annual Meeting of Architectural Institute of Japan (Kanto), B-2, 867-868, 2006 Sukun Kim, Shamim Pakzad, David Culler, James Demmel, GregoryFenves, Steven Glaser, and Martin Turon, “Health Monitoring of Civil Infrastructures Using Wireless SensorNetworks”, In the Proceedings of the 6th International Conference on Information Processing in Sensor Networks (IPSN '07) , Cambridge, MA, April2007, ACM Press, pp. 254-263.

  In a distributed system in which a plurality of sensor nodes are installed, accurate sampling (detection) history data at each sensor node is required in order to perform accurate earthquake observation and structural health monitoring. For this purpose, each sensor node must perform sampling at an accurate frequency while synchronizing timing (for sampling).

  If sampling at an accurate frequency is not realized, the waveform of acceleration input to the sensor cannot be restored from the acquired sample (sensor data). If the timing for sampling is not synchronized, the analysis of the seismic wave and the analysis of the seismic motion and the structure cannot be performed accurately.

  As described above, the sensor node mainly executes a task for performing wireless communication and a task for performing sampling. The task of sampling needs to be executed at an accurate frequency after being synchronized between sensor nodes as described above. However, depending on the performance of a CPU (Central Processing Unit) that executes the task, the task for sampling may not be executed at an accurate frequency due to the influence of the task for performing wireless communication. Specifically, for example, a task that performs wireless communication becomes inefficient when the task is interrupted due to an interrupt, so the priority is generally set high, so wireless communication is performed at the timing at which sampling should be performed. If the task has been executed, the sampling task is not executed at that timing. As a result, jitter occurs between the timing at which the sampling should be performed and the timing at which the sampling is actually performed, which causes a problem that sampling at an accurate timing and an accurate frequency cannot be performed.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to perform sampling at an accurate timing and frequency in a vibration measurement system that samples vibration by a sensor node.

  In order to achieve the above object, a vibration measurement system according to the present invention includes a sensor node provided at a predetermined position of an object to be measured and a management node that performs wireless communication with the sensor node. The vibration measurement system for measuring the vibration of the measurement object, wherein the sensor node performs wireless communication between the sensor side detection means for detecting the degree of vibration at a predetermined position of the measurement object and the management node. The sensor-side communication means and the sensor-side detection means are controlled to detect the degree of vibration at a predetermined cycle, and the sensor-side communication means is detected for the degree of vibration. And a sensor-side control unit that performs control for prohibiting wireless communication at the timing.

  In the vibration measurement system according to the present invention, wireless communication is prohibited at a timing at which the sensor node detects the degree of vibration at a predetermined period. Therefore, it is possible to prevent the sampling from being performed at an appropriate timing due to the influence of the wireless communication, and to prevent the occurrence of jitter. That is, according to the vibration measurement system of the present invention, sampling can be performed with accurate timing and frequency.

  The management node is provided in the measurement target, and the degree of vibration at the position where the node is provided is detected in a predetermined first time range by a management side detection unit that detects the degree of vibration at a predetermined cycle and the management side detection unit. And a collection request means for transmitting a data collection request to the sensor node based on the degree of vibration, and the sensor side communication means of the vibration sensor node receives the data collection request from the management node and detects the sensor side. It is desirable to transmit information indicating the degree of vibration detected by the means to the management node by wireless communication. In this configuration, information indicating the degree of vibration detected at the sensor node can be transmitted from the sensor node to the management node only when vibration occurs in the measurement object. That is, according to this configuration, information can be efficiently acquired in the vibration measurement system.

  The collection request unit of the management node calculates an average value of the degree of vibration detected in the predetermined second time range before the first time range by the management side detection unit, and the first value for the average value is calculated. It is desirable to calculate a variation in the degree of vibration detected in the time range and transmit a data collection request in accordance with the variation. According to this configuration, it is possible to appropriately acquire information in consideration of the temperature dependence of vibration detection by the detection means.

  Each component of the vibration measurement system according to the present invention has a particularly novel configuration. That is, the sensor node according to the present invention is a sensor node that is provided at a predetermined position of a measurement object where vibration is measured and performs wireless communication with a management node, and is a sensor node that performs vibration communication at a predetermined position of the measurement object. Control the sensor-side detection means for detecting the degree and the sensor-side communication means for performing wireless communication between the management node and the sensor-side detection means so that the detection of the degree of vibration is executed at a predetermined cycle. In addition, the sensor-side communication means includes sensor-side control means for performing control for prohibiting wireless communication at the timing when the detection of the degree of vibration is executed.

The management node according to the present invention includes a sensor node provided at a predetermined position of the measurement object and a management node provided on the measurement object and performing wireless communication with the sensor node. A management node in the vibration measurement system for measuring the vibration of the measurement object, the management side detection means for detecting the degree of vibration at the position where the node is provided at a predetermined cycle, and the management side detection means Collection request means for transmitting a data collection request to the sensor node based on the degree of vibration detected in a predetermined first time range;
And the collection request means calculates an average value of the degree of vibration detected in the predetermined second time range before the first time range by the management side detection means, and the first value for the average value is calculated. A variation in the degree of vibration detected in the time range is calculated, and a data collection request is transmitted according to the variation.

  According to the present invention, it is possible to prevent the sampling from being performed at an appropriate timing due to the influence of the wireless communication and to prevent the occurrence of jitter, so that the sampling can be performed at an accurate timing and frequency. That is, according to the present invention, accurate sampling and time synchronization are performed.

  Hereinafter, preferred embodiments of a vibration measurement system according to the present invention and sensor nodes and management nodes included in the vibration measurement system will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 shows a vibration measurement system 1 according to this embodiment. The vibration measurement system 1 is a system that measures vibration of a building structure 2 that is a measurement object. As shown in FIG. 1, the vibration measurement system 1 includes a plurality of sensor nodes 10 and one management node 20. The sensor node 10 and the management node 20 are each installed at a predetermined position of the building structure 2. Specifically, it is installed on each floor of the building structure 2, each corner of the floor, each room, and the like. Since the management node 20 performs wireless communication with each sensor node 10, it is preferable that the management node 20 be installed at a place where wireless communication is easily performed, for example, at a position that is substantially equal to the position where each sensor node 10 is disposed.

  The sensor node 10 and the management node 20 detect the degree of vibration at the position where each is installed in the building structure 2. The vibration measurement system 1 is a system that acquires and stores information indicating the degree of vibration at each position in the building structure 2 detected at each sensor node 10 and the management node 20. Information is acquired by the management node 20.

  Subsequently, the configuration of the sensor node 10 and the management node 20 configuring the vibration measurement system 1 will be described in detail. As shown in FIG. 1, the sensor node 10 includes a sensor side detection unit 11, a memory 12, a sensor side communication unit 13, and a sensor side control unit 14.

The sensor side detection unit 11 is a sensor side detection unit that detects the degree of vibration at the position where the sensor side detection unit 11 is installed in the building structure 2. The degree of vibration to be detected is, for example, an acceleration applied to the position, and is acquired as unit data such as cm / s ² (Gal). The detection (sampling) of acceleration by the sensor side detection unit 11 is performed at a period of 10 ms (at a frequency of 100 Hz) under the control of the sensor side control unit 14 as described later. The direction of acceleration to be detected is determined in advance by the direction in which the sensor node 10 is installed. The direction may be one direction or three directions so that a three-dimensional vibration direction can be detected (in that case, the x direction, the y direction, and the z direction are determined for each direction).

  The sensor side detection unit 11 stores information indicating the detected acceleration in the memory 12 in association with information indicating the detected timing. The information indicating the detected timing is, for example, a slot number notified from the management node 20. The slot numbers are numbers that are continuous according to time, and the information indicating the acceleration detected at the same timing in each sensor-side detection unit 11 is associated with the same slot number. Specifically, the sensor-side detection unit 11 is realized by an existing acceleration sensor using MEMS (Micro Electro Mechanical Systems) or the like.

  The memory 12 is means for storing data on the degree of vibration detected by the sensor side detection unit 11. Specifically, the slot number and the data indicating the magnitude of acceleration are associated with each other and stored for each data.

  The sensor-side communication unit 13 is a sensor-side communication unit that performs wireless communication with the management node 20. Information is transmitted and received between the sensor side communication unit 13 and the management node 20 via the wireless communication. Information transmitted from the management node 20 to the sensor side communication unit 13 includes a packet for performing time synchronization, a packet for performing synchronization of sampling timing by the sensor side detection unit 11 (sampling synchronization), and the like. The packet for performing sampling synchronization includes a slot number associated with the sampled data. The sensor side communication unit 13 outputs the received packet for performing sampling synchronization to the sensor side control unit 14.

  The sensor side communication unit 13 acquires information indicating the acceleration stored in the memory 12 and transmits the information to the management node 20 by wireless communication. The sensor side communication unit 13 receives a data collection request from the management node 20 by wireless communication, and transmits information indicating acceleration using the reception as a trigger. The data collection request is information for requesting information indicating acceleration from the management node 20 to each sensor node 10 (trigger). The data collection request is included in the packet for performing the synchronization described above. Specifically, information indicating a data collection request is included in a predetermined data area in the packet.

  After receiving the data collection request, the sensor side communication unit 13 receives information specifying the range of information indicating the requested acceleration from the management node 20, and acquires information indicating the acceleration from the memory 12 based on the information. . The range of information indicating the requested acceleration is specified by, for example, a slot number. In addition, when transmitting the information indicating the acceleration, the sensor side communication unit 13 also transmits the information specifying the own node 10 in association with the information, and which sensor node 10 the information indicating the acceleration is sampled. Can be determined.

  The wireless communication performed between the sensor side communication unit 13 and the management node 20 may be realized by the wireless communication module provided in the sensor node 10 and capable of communicating in the building structure 2. That is, it is only necessary to use wireless communication of several meters to several tens of meters including the building structure 2 in the communication area. Specifically, for example, it is realized by an existing wireless LAN (Local Area Network) or ZigBee.

  The sensor-side control unit 14 is a unit that performs information processing such as operations of the sensor-side detection unit 11 and the sensor-side communication unit 13 and calculations related to the operations. In particular, the sensor-side control unit 14 controls the sensor-side detection unit 11 to perform sampling at a predetermined period, and performs wireless communication with the sensor-side communication unit 13 at the above sampling timing. It is a sensor side control means which performs control which prohibits.

  The sensor side control unit 14 performs the following processing so as to execute sampling at a predetermined cycle. The sensor-side control unit 14 holds a timer, and performs time synchronization of the timer based on a packet that is transmitted from the management node 20 and received by the sensor-side communication unit 13. The sensor-side control unit 14 controls the sensor-side detection unit 11 to perform sampling at a predetermined timing based on a packet for timing synchronization transmitted from the management node 20 and received by the sensor-side communication unit 13. For example, sampling is executed at a cycle of 10 ms (frequency: 100 Hz) as shown in the diagram showing the task execution timing in the sensor node 10 of FIG. In FIG. 2, the horizontal axis indicates the time axis. Further, time synchronization and timing synchronization may be performed by one control packet.

  The sensor side control unit 14 is realized by a CPU included in the sensor node 10, and the control on the sensor side detection unit 11 is realized as a task executed by the CPU. High priority is set so that the sampling task is executed at an accurate cycle.

  The sensor-side control unit 14 performs the following processing so as to prohibit wireless communication at the sampling timing, that is, perform wireless communication between the sampling timings. As shown in FIG. 2, the sensor-side control unit 14 causes the sensor-side communication unit 13 to shift to a state (Rx) in which reception by wireless communication can be performed (RF (Radio) after 0.2 ms from the timing when the sampling is performed. Frequency) ON). After the sensor-side control unit 14 enters a state (Rx) in which the sensor-side communication unit 13 can receive by wireless communication, 9 ms later, reception (by transmission) of the sensor-side communication unit 13 is prohibited. (RF OFF). With the above control, the sensor node 10 receives (sets) a packet that synchronizes time and timing by wireless communication for only 9 ms between timings sampled by the sensor-side detection unit 11. Specifically, the above control can be realized by controlling a MAC layer (Media Access Control Layer).

  Thereby, in the sensor node 10, the task of radio | wireless communication and the task of sampling do not compete. As will be described later, the management node 20 transmits the above-described packet while the sensor node 10 can receive by wireless communication. Note that information indicating the timing of performing control as described above is stored in the sensor-side control unit 14 in advance by being input to a user or the like.

  As described above, the sensor node 10 is configured by hardware such as a CPU, a memory, an acceleration sensor, and a wireless communication module, and the above functions are exhibited by the operation thereof. In addition to the hardware related to the above function, the sensor node 10 includes a battery for operating the above components, a casing for storing the above components, and the like. The above is the configuration of the sensor node 10.

  As shown in FIG. 1, the management node 20 includes a management side detection unit 21, a memory 22, a management side communication unit 23, a management side control unit 24, and a collection request unit 25.

  The management-side detection unit 21 is a management-side detection unit that detects the degree of vibration at the position where the management-side detection unit 21 is installed in the building structure 2. The detection (sampling) of the degree of vibration is performed by the same configuration as that of the sensor side detection unit 11 of the sensor node 10. The management-side detection unit 21 stores information indicating the detected acceleration in the memory 22 in association with information indicating the detected timing.

  Similar to the memory 12 of the sensor node 10, the memory 22 is means for storing data on the degree of vibration detected by the management-side detection unit 21. Further, the memory 22 stores data of the degree of vibration detected by each sensor node 10 received by the management communication unit 23 as described below.

  The management-side communication unit 23 is a management-side communication unit that performs wireless communication with the sensor node 10. Information is transmitted and received between the management-side communication unit 23 and the sensor node 10 via the wireless communication. As described above, information transmitted from the management-side communication unit 23 to the sensor node 10 includes a packet for performing time synchronization and a timing synchronization (sampling synchronization) at which the sensor-side detection unit 11 performs sampling. There are packets. The packet for performing sampling synchronization includes a slot number associated with the sampled data. The above packet is input from the management-side control unit 24 and transmission is controlled.

  In addition, the management-side communication unit 23 transmits the above-described data collection request to each sensor node 10, receives information indicating the acceleration transmitted from the sensor node 10 accordingly, and stores the information in the memory 22. The data collection request is transmitted according to an instruction from the collection request unit 25. The wireless communication itself by the management side communication unit 23 is performed in the same manner as the sensor side communication unit 13 of the sensor node 10.

  The management-side control unit 24 is a unit that performs information processing such as operations of the management-side detection unit 21 and the management-side communication unit 23 and computations related to the operations. The management-side control unit 24 controls the management-side detection unit 21 so as to execute sampling at a predetermined cycle, and prohibits wireless communication from the management-side communication unit 23 at the above sampling timing. Management-side control means for performing control. As shown in the figure showing the task execution timing in the management node 20 of FIG. 2, the management-side control unit 24 controls the management-side detection unit 21 to perform sampling at a predetermined timing. For example, as shown in FIG. 2, sampling is executed at a cycle of 10 ms (frequency 100 Hz).

  The management-side control unit 24 is realized by a CPU included in the management node 20, and control for the sensor-side detection unit 11 is realized as a task executed by the CPU. High priority is set so that the sampling task is executed at an accurate cycle.

  In addition, the management-side control unit 24 performs the following processing between the own node 20 and each sensor node 10 so as to execute sampling at a predetermined cycle. The management-side control unit 24 holds a timer, generates a packet for time synchronization and a packet for timing synchronization based on the timer, and transmits the packets to the sensor nodes 10. As described above, as shown in FIG. 2, a packet is generated that causes sampling to be executed at a cycle of 10 ms (frequency 100 Hz). Note that information indicating how often the sampling is performed in the own node and each sensor node is stored in the management-side control unit 24 by being input to the user in advance.

  In addition, the management-side control unit 24 performs the following processing so that wireless communication is prohibited at the sampling timing in the node 20, that is, wireless communication is performed between the sampling timings. As shown in FIG. 2, the management-side control unit 24 shifts the management-side communication unit 23 to a state (Tx) in which wireless transmission can be performed (RF ON) 1.2 ms after the sampling is performed. . In addition, the management-side control unit 24 makes a state (Tx) in which wireless transmission can be performed with respect to the management-side communication unit 23, and after 4 ms, transmission to the management-side communication unit 23 by wireless communication (also reception). Transition to the prohibited state (RF OFF). With the control described above, the management node 20 is in a state in which the management side detection unit 21 can transmit a packet that synchronizes time and timing by wireless communication for only 4 ms between sampled timings. During this state, the management-side control unit 24 generates the packet and outputs the packet to the management-side communication unit 23 so that a packet that synchronizes time and timing is transmitted. The transmission to each sensor node 10 is controlled. As shown in FIG. 2, the timing for 4 ms in a state where the transmission can be performed is included in the timing for 9 ms at which each sensor node 10 receives a packet. As described above, the management node 20 does not compete between the wireless communication task and the sampling task. Note that information indicating the timing of performing control as described above is stored in the management-side control unit 24 in advance by being input to a user or the like.

  The collection request unit 25 is a collection request unit that transmits a data collection request to each sensor node 10 based on the magnitude of acceleration detected by the management side detection unit 21 in a predetermined time range (first time range). It is. This is because the management node 20 does not acquire all the acceleration magnitude data detected by the sensor node 10, but only when a predetermined magnitude of vibration is detected by the management node 20. 10 is for acquiring the data of the magnitude of the acceleration detected at 10. That is, the acceleration magnitude data is efficiently collected by collecting the acceleration magnitude data at the management node 20 only when vibrations occur in the building structure 2. The collection request unit 25 transmits a data collection request by wireless communication via the management side communication unit 23.

  The collection request unit 25 calculates an average value of the magnitudes of accelerations detected by the management side detection unit 21 in a predetermined time range (second time range) before the first time range, and It is desirable to calculate a variation in the magnitude of the acceleration detected in the first time range with respect to the average value and transmit a data collection request in accordance with the variation.

  Specifically, the collection request unit 25 refers to the sample stored in the memory 22 every time the data (sample) sampled by the management-side detection unit 21 is stored in the memory 22 as follows: It is determined whether or not a data collection request is transmitted to the sensor node 10. FIG. 3 shows an example of a graph indicating the magnitude of acceleration sampled by the management side detection unit 21. In FIG. 3, the horizontal axis represents the time axis, and the vertical axis represents the magnitude of acceleration.

  In FIG. 3, the first time range is a range R1 corresponding to the latest 256 samples from the latest detection result sample. When the time T at which the latest detection result is detected is used, the first time range R1 is expressed as “T−2.56 [sec] <t ≦ T [sec]”. Further, the second time range is set to a range R2 corresponding to the past 1281 samples to the past 2304 samples (tracing back from the latest sample). The second time range R2 is expressed as “T-23.04 [sec] <t ≦ T-12.08 [sec]”. Here, it is preferable that the first time range R1 includes a sample including the latest detection result as much as possible or close to the latest detection result as described above. Also, the second time range R2 is preferably a time range that is several seconds to several minutes before the first time range. Note that the first time range R1 and the second time range R2 do not have to be adjacent to each other. The collection request unit 25 stores in advance information for determining which sample corresponds to the first or second time range R1, R2 with respect to the latest detection result sample.

First, the collection request unit 25 acquires a sample of the second time range R2 from the memory 22, and calculates an average value of these values (a value indicating the magnitude of acceleration, the same applies hereinafter). Subsequently, the collection request unit 25 acquires a sample of the first time range R1 from the memory 22, and obtains an average of square values of values obtained by subtracting the average value from the values of the samples as values indicating the variation. A value (RMS value: Root Mean Square) is calculated. When the average value of the samples in the second time range R2 is a and each value of the samples in the first time range R1 is r _i (i is a subscript indicating each sample), Σ (r _i −a ² / n is calculated.

  If the collection request unit 25 determines that the value indicating the variation is equal to or greater than the threshold value, it is determined that a vibration (for example, an earthquake) of a certain magnitude or more has occurred in the building structure 2 and a data collection request is made. Is transmitted to each sensor node 10. The above threshold value is a value that can detect the occurrence of vibration in the building structure 2 and is stored in the collection request unit 25 in advance by being input to a user or the like. Further, the collection request unit 25 continues to calculate a value indicating the above-described variation even after determining that the data collection request is transmitted, and if it is determined that the value is below the threshold, the vibration generated in the building structure 2 is reduced. Judge that Here, it is assumed that the above threshold value is a value that can detect that the vibration in the building structure 2 has settled, and is stored in the collection request unit 25 in advance by being input to a user or the like. Further, this threshold value may be the same as or different from the threshold value for determining the occurrence of an earthquake.

  When the collection request unit 25 detects the occurrence and end of vibration, the collection request unit 25 specifies the range of samples to be acquired from each sensor node 10 based on the timings. Specifically, the above-mentioned range may be from the timing of the occurrence of the earthquake to the timing of termination, or it may be the above-mentioned range from a little before the timing of occurrence of the earthquake to a little later than the timing of occurrence of the earthquake. Good. This range is specified by, for example, a slot number.

  When the magnitude of acceleration in a plurality of directions is detected by the management side detection unit 21, the above processing is performed for each direction in which acceleration is detected. That is, if it is determined that the RMS value is equal to or greater than the threshold value in any one direction, it is determined that a data collection request is transmitted to each sensor node 10.

  When the collection request unit 25 specifies the range of samples acquired from each sensor node 10, the collection request unit 25 includes the data collection request in a packet transmitted to the sensor node 10 for synchronization. Thereafter, the collection request unit 25 notifies each sensor node 10 of the range of samples to be collected by wireless communication via the management-side communication unit 23.

  As described above, with the average value of the sample values in the second time range R2 as the reference value (zero point), the vibration in the building structure 2 is determined from the sample values in the first time range R1. This takes into account the temperature dependence of the management-side detection unit 21 (acceleration sensor). The performance of the acceleration sensor changes depending on the temperature, and the magnitude of the detected acceleration corresponds to the temperature. Therefore, even if calibration has been performed in advance, there is a possibility that accurate vibration cannot be detected if the temperature changes from that at the time of calibration. As described above, if the sample in the second time range R2 in which vibration is not generated (assumed to be a reference value) is used as a reference value, the building structure 2 is appropriately formed in consideration of the temperature dependency as described above. It can be determined that vibration has occurred.

  The collection request unit 25 is realized by a CPU provided in the management node 20. The CPU that implements the collection request unit 25 and the CPU that implements the management-side control unit 24 may be the same CPU, but are preferably separate CPUs in terms of processing efficiency.

  Similar to the sensor node 10, the management node 20 is configured by hardware such as a CPU, a memory, an acceleration sensor, and a wireless communication module as described above. . The management node 20 includes a battery for operating the above components, a casing for storing the above components, and the like in addition to hardware related to the above functions. The above is the configuration of the management node 20.

  Subsequently, processing executed by the vibration measurement system 1 according to the present embodiment will be described using the flowchart of FIG.

  In each sensor node 10, the sensor side detection unit 11 detects (sampling) the magnitude of acceleration (in accordance with the control of the sensor side control unit 14) (S11). The sampling is performed at the same timing in all the sensor nodes 10, that is, the timing synchronization is taken. The sampled acceleration data is stored in the memory 12. While sampling is being performed, the sensor-side control unit 14 prohibits wireless communication by the sensor-side communication unit 13. 0.2 ms after the sampling is performed, the sensor-side control unit 14 shifts to a state in which the sensor-side communication unit 13 can receive by wireless communication under the control of the sensor-side control unit 14.

  On the other hand, also in the management node 20 (according to control of the management side control unit 24), the management side detection unit 21 detects (sampling) the magnitude of acceleration (S21). The sampling is performed at the same timing as the sensor node 10. The sampled acceleration data is stored in the memory 22. While sampling is being performed, wireless communication by the management-side communication unit 23 is prohibited by the management-side control unit 24. 1.2 ms after sampling is performed, the management-side communication unit 23 shifts to a state in which transmission by wireless communication is possible under the control of the management-side control unit 24. Subsequently, a packet for performing time synchronization and (sampling) timing synchronization is transmitted from the management side control unit of the management node 20 to each sensor node 10 by wireless communication via the management side communication unit 23 (S22). Subsequently, the management-side communication unit 23 is shifted to a state in which wireless communication is prohibited under the control of the management-side control unit 24 4 ms after the timing at which wireless communication transmission is permitted.

  In each sensor node 10, the above-described packet is received by the sensor side communication unit 13 (S12). The received packet is input from the sensor side communication unit 13 to the sensor side control unit 14. Subsequently, 9 ms after the timing when reception of wireless communication is permitted, the sensor-side communication unit 13 is shifted to a state where wireless communication is prohibited under the control of the sensor-side control unit 14. Further, based on the received packet, the sensor-side control unit 14 performs a synchronization process.

  In each sensor node 10, the magnitude of acceleration is detected by the sensor side detection unit 11 at the timing when the synchronization processing is performed, that is, 10 ms after the previous sampling (S11). In the management node 20, the magnitude of acceleration is detected by the management side detection unit 21 at the timing when the synchronization processing is performed, that is, 10 ms after the previous sampling (S21). As described above, sampling, transmission / reception of synchronization packets, and synchronization processing (S11, S12, S21, S22) are repeatedly performed. As a result, sampling is performed at a predetermined frequency.

  In the management node 20, every time sampling is performed, the above-described RMS value is calculated by the collection request unit 25, and occurrence of vibrations of a certain magnitude or more in the building structure 2 is detected based on the RMS value. It is determined whether or not (S23). If the occurrence of vibration is not detected, sampling and transmission of synchronization packets (S21, S22) are repeated.

  When the occurrence of vibration is detected, the collection request unit 25 calculates the RMS value described above, and determines whether the vibration in the building structure 2 has ended based on the RMS value. Although determination of the end of vibration is not shown in FIG. 4, sampling and transmission of a synchronization packet (S21, S22) are repeated after vibration is detected.

  When the end of vibration is detected, a data collection request is transmitted from the collection request unit 25 to each sensor node 10 by wireless communication via the management-side communication unit 23 (S24). In addition, after the data collection request is transmitted, the collection request unit 25 transmits information for specifying the sample range related to the data collection request. The information specifying the sample range may be transmitted after receiving a response (Ack) (survival response) to the data collection request from the sensor node 10.

  In each sensor node 10, the sensor side communication unit 13 receives a data collection request and information specifying the range of samples to be transmitted (S13). Subsequently, based on the received information, the sensor-side communication unit 13 acquires information indicating acceleration from the memory 12 and transmits the information to the management node 20 (S14). In the management node 20, information indicating the acceleration transmitted from each sensor node 10 is received by the management side communication unit 23 and stored in the memory 22.

  After the information indicating the acceleration is transmitted / received, each sensor node 10 and management node 20 repeats the sampling, the transmission / reception of the synchronization packet, and the synchronization process (S11, S12, S21, S22). In each sensor node 10, the above-described sampling, synchronization packet transmission / reception, and synchronization processing (S11, S12) are repeatedly performed, triggered by reception of a packet for time synchronization by the sensor side communication unit 13. May be.

  The above is the processing executed by the vibration measurement system 1 according to the present embodiment. As a result of the above processing, the memory 22 of the management node 20 stores vibration data generated in the building structure 2 detected by the sensor nodes 10 and the management node 20.

  As described above, in the vibration measurement system 1 according to the present embodiment, the wireless communication is prohibited at the timing when the degree of vibration is detected at a predetermined cycle in each sensor node 10 and the management node 20. Therefore, it is possible to prevent the sampling from being performed at an appropriate timing due to the influence of the wireless communication, and to prevent the occurrence of jitter. That is, according to the vibration measurement system 1 according to the present embodiment, sampling can be performed with accurate timing and frequency. That is, according to the present embodiment, accurate sampling and time synchronization are performed.

  Note that, for example, the above effect cannot be obtained only by setting a higher priority than wireless communication for a task for sampling. This is because a task for performing wireless communication causes a large overhead when interrupted by a task for performing sampling, and therefore, when performing sampling at an interval of about 10 ms, there is a problem that appropriate wireless communication cannot be performed.

  Note that it is considered that a sufficiently high speed CPU of about several hundred MHz can substantially keep the sampling jitter within a relatively negligible range without using the function of the present invention. However, if the function of the present invention is used, it is possible to perform sampling at an accurate timing and frequency even if a CPU having a relatively low performance of about 10 MHz is used. Normally, when it is desired to measure vibration accurately, it is preferable to provide a larger number of sensor nodes 10. Therefore, it is extremely useful to perform sampling at an accurate timing and frequency even when a relatively inefficient CPU is used. It is.

  Further, as in the present embodiment, it is preferable that the management node 20 also detects the degree of vibration and transmits a data collection request to each sensor node 10 based on the degree of vibration to collect data. . According to this configuration, information indicating the degree of vibration detected at the sensor node 10 can be transmitted from the sensor node 10 to the management node 20 only when vibration due to an earthquake occurs in the building structure 2. . That is, according to this configuration, in the vibration measurement system 1, for example, only data that needs to be analyzed can be stored in the management node 20, and information can be efficiently acquired. However, the configuration as described above is not necessarily required. Even if information on the degree of vibration is transmitted from the sensor node 10 to the management node 20 at a predetermined timing (for example, once a day) or the like. Good.

  Further, as in the present embodiment, it is desirable to determine whether to transmit a data collection request using the average value of the second time range R2. According to this configuration, it is possible to appropriately acquire information in consideration of the temperature dependency of vibration detection by the management-side detection unit 21. However, the configuration as described above is not necessarily required, and it is determined whether or not to transmit a data collection request by using only the value of the first time range R1 (for example, dispersion of those values). It is good.

  In the present embodiment, the vibration measurement object by the vibration measurement system 1 is the building structure 2. However, the vibration measurement system 1 does not necessarily need to be the building structure 2, and vibration measurement is required. I just need it.

  In the present embodiment, the magnitude of acceleration is used as the degree of vibration detected by each sensor node 10 and management node 20, but the position of each node 10, 20 of the measurement object is installed. It is good also as detecting a displacement and distortion.

It is a figure which shows the vibration measurement system in embodiment of this invention, and the sensor node and management node which are included in the said vibration measurement system. It is a figure which shows the timing when the transmission / reception of the information by sampling and radio | wireless communication is performed in a sensor node and a management node. It is a graph which shows the time series data of the magnitude | size of the acceleration detected in a management node. It is a flowchart which shows the process performed with the vibration measuring system in embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Vibration measuring system, 2 ... Building structure, 10 ... Sensor node, 11 ... Sensor side detection part, 12 ... Memory, 13 ... Sensor side communication part, 14 ... Sensor side control part, 20 ... Management node, 21 ... Management Side detection unit, 22 ... memory, 23 ... management communication unit, 24 ... management control unit, 25 ... collection request unit.

Claims (5)

A vibration measurement system for measuring vibration of the measurement object, comprising a sensor node provided at a predetermined position of the measurement object and a management node that performs wireless communication with the sensor node,
The sensor node is
Sensor-side detection means for detecting the degree of vibration at a predetermined position of the measurement object;
Sensor-side communication means for performing the wireless communication with the management node;
The sensor-side detection means is controlled to execute the detection of the degree of vibration at a predetermined cycle, and the timing at which the sensor-side communication means is detected to detect the degree of vibration. Sensor-side control means for performing control to prohibit the wireless communication;
A vibration measurement system comprising: The management node is
Provided in the measurement object,
Management-side detection means for detecting the degree of vibration at the position where the node is provided at a predetermined period;
A collection request means for transmitting a data collection request to the sensor node based on the degree of vibration detected by the management side detection means in a predetermined first time range;
With
Sensor-side communication means of the vibration sensor node receives the data collection request from the management node, and transmits information indicating the degree of vibration detected by the sensor-side detection means to the management node. The vibration measurement system according to claim 1, wherein the vibration measurement system transmits the vibration.   The collection request unit of the management node calculates an average value of the degree of vibration detected in a predetermined second time range before the first time range by the management side detection unit, and calculates the average value The vibration measurement system according to claim 2, wherein a variation in the degree of vibration detected in the first time range is calculated, and the data collection request is transmitted according to the variation. A sensor node that is provided at a predetermined position of a measurement object on which vibration is measured and performs wireless communication with a management node,
Sensor-side detection means for detecting the degree of vibration at a predetermined position of the measurement object;
Sensor-side communication means for performing the wireless communication with the management node;
The sensor-side detection means is controlled to execute the detection of the degree of vibration at a predetermined cycle, and the timing at which the sensor-side communication means is detected to detect the degree of vibration. Sensor-side control means for performing control to prohibit the wireless communication;
A sensor node comprising: Measure vibration of the measurement object, including a sensor node provided at a predetermined position of the measurement object, and a management node provided on the measurement object and performing wireless communication with the sensor node. A management node in the vibration measurement system
Management-side detection means for detecting the degree of vibration at the position where the node is provided at a predetermined period;
A collection request means for transmitting a data collection request to the sensor node based on the degree of vibration detected by the management side detection means in a predetermined first time range;
With
The collection requesting unit calculates an average value of the degree of vibration detected in the predetermined second time range before the first time range by the management-side detection unit, and calculates the first value for the average value. A management node that calculates a variation in the degree of vibration detected in the time range and transmits the data collection request according to the variation.

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