Seismic sensor, earthquake determination method, and earthquake determination program

Abstract

A seismic sensor (10) comprises an acceleration acquiring unit (21), a total speed change amount calculating unit (24), a total change amount variation determining unit (25), and an earthquake determining unit (26). The acceleration acquiring unit (21) acquires the acceleration of a vibration. The total speed change amount calculating unit (24) calculates a total speed change amount in a predetermined fixed segment on the basis of the acceleration acquired by the acceleration acquiring unit (21). The total change amount variation determining unit (25) determines the presence or absence of variation in the total speed change amount calculated by the total speed change amount calculating unit (24) in each of a plurality of the predetermined fixed segments. The earthquake determining unit (26) determines whether or not the vibration is an earthquake in accordance with the determination result of the presence or absence of variation by the total change amount variation determining unit (25).

Description

Seismic sensor, earthquake determination method, and earthquake determination program

[0001] The present invention relates to a seismic sensor for detecting seismic motion, an earthquake determination method, and an earthquake determination program.

[0002] In recent years, seismic sensors have been built into gas meters, electricity meters, distribution boards, outlets, etc., and when seismic motion of a magnitude greater than or equal to a predetermined value (for example, seismic intensity 5+ or higher) is detected, a cutoff signal for shutting off the supply of gas, electricity, etc. is output. For example, Patent Document 1 discloses a seismic sensor that outputs a cutoff signal when an index value indicating the scale of an earthquake in the earthquake processing period after the determination period during the earthquake processing period is greater than or equal to a threshold value, and a continuous earthquake determination unit that determines the occurrence of an earthquake based on the acceleration measured during the earthquake processing period, and a cutoff determination unit that prevents the cutoff signal from being output regardless of the index value when the continuous earthquake determination unit determines that no earthquake has occurred.

[0003] Japanese Patent No. 6465257

[0004] However, the above conventional seismic sensors have the following problems. That is, in the seismic sensor disclosed in the above publication, if there is even a slight noise characteristic in the detected vibration, there is a risk of misjudging the vibration as noise. In addition, since the noise characteristics change depending on the device or installation environment to which the seismic sensor is attached, it is difficult to accurately detect noise, and there is also a risk of misjudging noise as an earthquake.

[0005] An object of the present invention is to provide a seismic sensor, an earthquake determination method, and an earthquake determination program that can accurately determine whether the detected vibration is an earthquake or noise.

[0006] (Means for solving the problem) The seismic sensor according to the first invention comprises an acceleration acquisition unit, a total speed change calculation unit, a total change variation determination unit, and an earthquake determination unit. The acceleration acquisition unit acquires the acceleration of the vibration. The total speed change calculation unit calculates the total speed change over a predetermined fixed interval based on the acceleration acquired by the acceleration acquisition unit. The total change variation determination unit determines whether or not there is variation in the total speed change calculated by the total speed change calculation unit in each of a plurality of predetermined fixed intervals. The earthquake determination unit determines whether or not the vibration is an earthquake according to the determination result of the total change variation determination unit regarding the presence or absence of variation.

[0007] Here, to avoid misidentifying vibrations caused by factors other than earthquakes as earthquakes, for example, the seismic sensor determines whether the detected vibration is an earthquake based on the result of determining whether there is variation in the total change in velocity over a certain period, which is calculated from the acceleration of the vibration. In this case, the seismic sensor is installed, for example, on energy measuring instruments such as gas and electricity, and is set up to shut off the energy supply if an earthquake of a predetermined seismic intensity or higher is detected.

[0008] The acceleration acquisition unit may be configured to directly measure the acceleration of vibrations applied to the seismic sensor, or it may be configured to acquire the measured acceleration. The total change in velocity over a predetermined fixed interval is the sum of the changes in velocity over a fixed interval calculated from the acceleration from the start to the end of the vibration, and is used to distinguish whether the vibration is caused by a force of approximately constant magnitude or by forces of various magnitudes specific to earthquakes.

[0009] Here, if the variation in the total change in velocity over a predetermined interval is smaller than a predetermined threshold, it is estimated that the vibration is being subjected to a nearly constant force, and therefore the detected vibration is estimated to exhibit noise characteristics. Conversely, if the variation in the total change in velocity over a predetermined interval is greater than or equal to a predetermined threshold, it is estimated that the vibration is being subjected to forces of various magnitudes characteristic of earthquakes, and therefore the detected vibration is estimated to exhibit earthquake characteristics. As a result, by determining whether the detected vibration is an earthquake or noise based on the variation in the total change in velocity over a predetermined period from the acceleration of the detected vibration, it is possible to detect vibrations being subjected to a nearly constant force as noise without misidentifying them as earthquakes. Consequently, it is possible to accurately determine whether the detected vibration is an earthquake or noise.

[0010] The seismic sensor according to the second invention is the same as the seismic sensor according to the first invention, and the total change in speed calculation unit calculates the total change in speed by integrating the absolute value of the acceleration over a certain interval. As a result, it is possible to determine with high accuracy whether the detected vibration is an earthquake or noise using the total change in speed calculated by integrating the absolute value of the acceleration over a certain interval.

[0011] The seismic sensor according to the third invention is a seismic sensor according to the first or second invention, wherein the earthquake determination unit determines that the variation in the total change amount determination unit is smaller than a predetermined threshold, and determines that the vibration is noise. As a result, it is possible to accurately determine that the detected vibration is noise when the variation in the total change amount is small, without showing the earthquake characteristic of a large variation in the total change amount.

[0012] The seismic sensor according to the fourth invention is a seismic sensor according to the first or second invention, wherein the earthquake determination unit determines that the vibration is an earthquake when the total change variation determination unit determines that the variation is above a predetermined threshold. As a result, if the vibration exhibits the characteristic of an earthquake, such as a large variation in the total change in velocity, it is possible to accurately determine that the detected vibration is an earthquake.

[0013] The fifth seismic sensor is a seismic sensor according to the first or second invention, further comprising an acceleration waveform generation unit that generates an acceleration waveform showing the relationship between acceleration measured in the acceleration acquisition unit and elapsed time. The total speed change calculation unit calculates the total speed change from the acceleration waveform generated in the acceleration waveform generation unit. By using the acceleration waveform showing the relationship between acceleration measured in the acceleration acquisition unit and elapsed time to calculate the variation in the total speed change, it is possible to determine with high accuracy whether the detected vibration is an earthquake or noise.

[0014] The sixth seismic sensor is a seismic sensor according to the first or second invention, further comprising an earthquake magnitude calculation unit that determines whether an earthquake is of a predetermined seismic intensity or higher when an earthquake is determined to have occurred by an earthquake determination unit. This improves user safety by, for example, outputting a shutoff signal to stop the supply of energy such as electricity or gas if the earthquake magnitude is determined to be seismic intensity 5 or higher, which may pose risks such as fire or gas leaks.

[0015] The seismic sensor according to the seventh invention is a seismic sensor according to the first or second invention, further comprising a startup determination unit that calculates the intensity of vibration from the measurement results in the acceleration acquisition unit and switches from a power-saving mode to a measurement mode that consumes more power than the power-saving mode if the intensity of vibration is greater than or equal to a predetermined magnitude. As a result, by switching to a measurement mode that performs earthquake determination processing using the vibration acceleration waveform only when the detected intensity of vibration is greater than or equal to a predetermined magnitude (for example, equivalent to seismic intensity 4), it is possible to perform highly accurate earthquake determination while suppressing power consumption.

[0016] The eighth seismic sensor is a seismic sensor according to the first or second invention, further comprising an output control unit that outputs a predetermined signal when an earthquake is determined to have occurred in the earthquake determination unit. This allows the output unit to output, for example, a shut-off signal to stop the supply of energy such as electricity or gas, or a warning signal to indicate danger, when an earthquake occurs.

[0017] The seismic sensor according to the ninth invention is a seismic sensor according to the first or second invention, further comprising a storage unit for storing the judgment results of the total change variation determination unit and the earthquake determination unit. This allows necessary information to be retrieved from the storage unit that stores each judgment result, and the earthquake determination result and other information can be displayed or notified.

[0018] The earthquake determination method according to the tenth invention acquires the acceleration of vibration, calculates the total change in velocity over a certain period from the acquired acceleration from the start to the end of vibration, determines whether or not there is variation in the calculated total change in velocity, and determines whether or not the vibration is an earthquake according to the result of the determination of whether or not there is variation.

[0019] Here, to avoid misidentifying vibrations caused by factors other than earthquakes as earthquakes, for example, the seismic sensor determines whether the detected vibration is an earthquake based on the result of determining whether there is variation in the total change in velocity over a certain period, which is calculated from the acceleration of the vibration. In this case, the seismic sensor is installed, for example, on energy measuring instruments such as gas and electricity, and is set up to shut off the energy supply if an earthquake of a predetermined seismic intensity or higher is detected.

[0020] The acquisition of acceleration may involve directly measuring the acceleration of vibrations applied to the seismic sensor, or it may involve acquiring the measured acceleration. The total change in velocity over a certain period is the sum of the changes in velocity over a certain period calculated from the acceleration from the start to the end of the vibration, and is used to distinguish whether the vibration is caused by a force of approximately constant magnitude or by forces of various magnitudes specific to earthquakes.

[0021] Here, if the variation in the total change in velocity over a certain period is smaller than a predetermined threshold, it is estimated that the vibration is being subjected to a nearly constant force, and therefore the detected vibration is estimated to exhibit noise characteristics. Conversely, if the variation in the total change in velocity over a certain period is greater than or equal to a predetermined threshold, it is estimated that the vibration is being subjected to forces of various magnitudes characteristic of earthquakes, and therefore the detected vibration is estimated to exhibit earthquake characteristics. As a result, by determining whether the detected vibration is an earthquake or noise based on the variation in the total change in velocity over a certain period from the acceleration of the detected vibration, it is possible to detect vibrations being subjected to a nearly constant force as noise without misidentifying them as earthquakes. Consequently, it is possible to accurately determine whether the detected vibration is an earthquake or noise.

[0022] The earthquake determination program according to the eleventh invention acquires the acceleration of vibration, calculates the total change in velocity over a certain period from the acquired acceleration from the start to the end of vibration, determines whether or not there is variation in the calculated total change in velocity, and causes the computer to execute an earthquake determination method that determines whether or not the vibration is an earthquake according to the result of the determination of whether or not there is variation.

[0023] Here, to avoid misidentifying vibrations caused by factors other than earthquakes as earthquakes, for example, the seismic sensor determines whether the detected vibration is an earthquake based on the result of determining whether there is variation in the total change in velocity over a certain period, which is calculated from the acceleration of the vibration. In this case, the seismic sensor is installed, for example, on energy measuring instruments such as gas and electricity, and is set up to shut off the energy supply if an earthquake of a predetermined seismic intensity or higher is detected.

[0024] The acquisition of acceleration may involve directly measuring the acceleration of vibrations applied to the seismic sensor, or it may involve acquiring the measured acceleration. The total change in velocity over a certain period is the sum of the changes in velocity over a certain period calculated from the acceleration from the start to the end of the vibration, and is used to distinguish whether the vibration is caused by a force of approximately constant magnitude or by forces of various magnitudes specific to earthquakes.

[0025] Here, if the variation in the total change in velocity over a certain interval is smaller than a predetermined threshold, it is estimated that the vibration is being subjected to a nearly constant force, and therefore the detected vibration is estimated to be a vibration exhibiting noise characteristics. Conversely, if the variation in the total change in velocity over a certain interval is greater than or equal to a predetermined threshold, it is estimated that the vibration is being subjected to a force of various magnitudes characteristic of earthquakes, and therefore the detected vibration is estimated to be a vibration exhibiting earthquake characteristics.

[0026] This allows the system to determine whether a detected vibration is an earthquake or noise based on the variation in the total change in velocity over a certain period, derived from the acceleration of the detected vibration. This enables the detection of vibrations where a nearly constant force is continuously applied, without misidentifying them as earthquakes. As a result, it is possible to accurately determine whether a detected vibration is an earthquake or noise.

[0027] (Effects of the Invention) According to the seismic sensor of the present invention, it is possible to accurately determine whether the detected vibration is an earthquake or noise.

[0028] A control block diagram showing the configuration of an earthquake sensor according to one embodiment of the present invention. A functional block diagram generated within the earthquake sensor in Figure 1. (a) is a graph showing the acceleration waveform of vibration detected by the earthquake sensor in Figure 2. (b) is a graph showing the relationship between the absolute value of the acceleration of the acceleration waveform in (a) and the passage of time. (a) is a graph showing the total change in velocity calculated from the acceleration of vibration when the vibration detected by the earthquake sensor in Figure 2 is noise. (b) is a graph showing the total change in velocity calculated from the acceleration of vibration when the vibration detected by the earthquake sensor in Figure 2 is an earthquake. (a) and (b) are diagrams illustrating the calculation of the coefficient of variation used for earthquake determination using the variation in the total change in velocity. A flowchart showing the processing flow of the earthquake determination method executed by the earthquake sensor in Figure 2.

[0029] An earthquake sensor according to one embodiment of the present invention will be described below with reference to Figures 1 to 6. In this embodiment, unnecessary detailed explanations may be omitted. For example, detailed explanations of already well-known matters and redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding by those skilled in the art. Furthermore, the applicant provides the accompanying drawings and the following explanation so that those skilled in the art can fully understand the present invention, and does not intend to limit the subject matter described in the claims by means of these.

[0030] (1) Configuration of the seismic sensor 10 The seismic sensor 10 according to this embodiment includes an acceleration sensor 11, a controller 12, a memory 13, and an output unit 14, as shown in Figure 1.

[0031] The acceleration sensor 11 is, for example, an acceleration sensor using a piezoelectric element or an acceleration sensor that detects capacitance between electrodes. The acceleration measured (also called "sampling") by the acceleration sensor 11 is output to the controller 12. The controller 12 is, for example, a general-purpose integrated circuit that acquires the acceleration measured by the acceleration sensor 11 at a predetermined period and uses the acquired acceleration to determine whether an earthquake has occurred and to calculate an index value indicating the magnitude of the earthquake.

[0032] Furthermore, the controller 12 operates in different modes, either active mode or sleep mode, depending on the situation. Sleep mode is a mode in which the controller 12 operates with limited functionality, such as stopping instruction execution while accepting interrupts or stopping the supply of the clock. In this sleep mode, power consumption can be reduced compared to active mode.

[0033] The active mode is a mode in which the system performs processing to determine whether the detected vibration is an earthquake or noise, and calculates an index value indicating the magnitude of the earthquake. The functional blocks (see Figure 2) generated by the CPU in the seismic sensor 10 reading the earthquake judgment program stored in the memory 13 will be described in detail later. The memory 13 is a temporary storage means such as RAM (Random Access Memory) or a non-volatile memory such as EPROM (Erasable Programmable Read Only Memory), and stores, for example, the acceleration measured by the acceleration sensor 11 and threshold values ​​used for earthquake judgment.

[0034] The memory 13 may be a memory built into the acceleration sensor 11 or the controller 12. The output unit 14 is, for example, an output terminal of the controller 12, and when the controller 12 determines, for example, that an earthquake has occurred, it outputs information indicating the occurrence and magnitude of the earthquake to other devices via the output unit 14. In addition, when an earthquake of a predetermined magnitude or greater is detected, the output unit 14 outputs a shut-off signal to an external device to stop the supply of energy such as electricity or gas.

[0035] (2) Functional Blocks of the Seismic Sensor 10 As shown in Figure 2, the seismic sensor 10 includes an acceleration acquisition unit 21, an acceleration waveform generation unit 22, a vibration intensity classification and activation determination unit 23, a total speed change calculation unit 24, a total change variation determination unit 25, an earthquake determination unit 26, an earthquake magnitude calculation unit 27, an output control unit 28, and a storage unit 30. These functional blocks shown in Figure 2 are configured by the controller 12, which receives acceleration data acquired from the acceleration sensor 11 and reads the program stored in the memory 13.

[0036] The acceleration acquisition unit 21 acquires acceleration measurement data measured at a predetermined period by the acceleration sensor 11. Typically, the acceleration acquisition unit 21 acquires acceleration measurement data that is repeatedly measured at a relatively low speed (i.e., a relatively large measurement period). When performing acceleration sampling at such a low speed, the controller 12 basically operates in a low-power sleep mode (standby state or power-saving mode). In the standby state, the acceleration sensor 11 is in an operating state that performs sampling at a low speed, so the controller 12 operates in a sleep mode with limited functionality to suppress power consumption.

[0037] Furthermore, when the acceleration acquisition unit 21 acquires vibrations greater than a threshold preset in the memory unit 30, the acceleration sensor 11 repeatedly measures acceleration at a higher speed (i.e., with a relatively smaller period) than during low-speed sampling. In such high-speed sampling, the controller 12 operates in sleep mode or active mode. Note that when the earthquake determination unit 26, etc., described later, performs processing, the controller 12 operates in active mode (measurement mode). The transition from power-saving mode to measurement mode is called activating the seismic sensor 10.

[0038] The measurement mode is an operating state that performs high-speed sampling. Therefore, the controller 12 may operate in a sleep mode with limited functionality, or in an active mode that allows it to operate with maximum computing power. In the measurement mode, the sampling period is shortened, and the controller 12 switches from sleep mode to active mode, resulting in higher power consumption than in the power-saving mode.

[0039] The acceleration waveform generation unit 22 generates an acceleration waveform (see Figure 3(a)) that shows the relationship between the acceleration measured by the acceleration acquisition unit 21 and the elapsed time. The vibration intensity classification and activation determination unit 23 is a function of the acceleration sensor 11, and compares the acceleration value acquired by the acceleration acquisition unit 21 with the activation threshold held in the storage unit 30. If the acceleration value exceeds the activation threshold, it switches from power saving mode to measurement mode (activates the seismic sensor 10).

[0040] Further, the vibration intensity classification / start determination unit 23 calculates the intensity of vibration from the result of measurement in the acceleration acquisition unit 21, and when the vibration intensity is equal to or greater than a predetermined magnitude, it shifts from the power saving mode to the measurement mode with higher power consumption than the power saving mode (starts the controller 12). Here, the vibration intensity classification process performed by the vibration intensity classification / start determination unit 23 is implemented by performing filtering processing on the value of acceleration acquired by the acceleration acquisition unit 21. At this time, the filtered acceleration is stored in the storage unit 30.

[0041] The total speed change amount calculation unit 24 calculates the total speed change amount in a certain interval from the acceleration from the start to the end of vibration measurement in the acceleration acquisition unit 21. Specifically, the total speed change amount calculation unit 24 generates a waveform of the absolute value of acceleration (|a(t)|) shown in FIG. 3(b) from the acceleration waveform shown in FIG. 3(a) generated by the acceleration waveform generation unit 22, and integrates the absolute value of acceleration in a certain interval to calculate the total speed change amount (Δv Ｎ ).

[0042] The total speed change amount Δv Ｎ is calculated by integrating the absolute value of acceleration for each certain interval (for example, three sections separated by a broken line (assuming 1 second per section, it is 3 seconds)). For example, when the detected vibration is noise, the total speed change amount calculated by the total speed change amount calculation unit 24 has little variation and is almost a constant value as shown in FIG. 4(a).

[0043] This is presumably meant to be "vibration with almost the same magnitude of force continuously applied", which is a characteristic of noise. When the detected vibration is an earthquake, the total speed change amount calculated by the total speed change amount calculation unit 24 has large variation as shown in FIG. 4(b). This is presumably meant to be "vibration with various magnitudes of force continuously applied", which is a characteristic of an earthquake.

[0044] The total change amount variation determination unit 25 determines whether there is variation in the total change amount of speed calculated by the speed total change amount calculation unit 24. Here, in the seismic sensor 10 of the present embodiment, in the seismic determination method described later, the coefficient of variation is calculated from the total change amount of speed in a certain section to determine whether it is an earthquake or noise. For example, for the eight sections shown in FIG. 5(a), the total change amount of speed Δv Ｎ (N = 1, 2, 3, 4, 5, 6, 7, 8) is, as shown in FIG. 5(b), the speed total change amount calculation unit 24 calculates Δv Ｎ = 12, 15, 8, 8, 14, 15, 9, 15.

[0045] Let the average value μ, standard deviation σ, and coefficient of variation CV of the total change amount of speed, then the coefficient of variation CV is calculated using the following relational expressions (1), (2), and (3).

[0046]

[0047]

[0048] Therefore, in the example shown in FIGS. 5(a) and 5(b), since the average value = 12 and the standard deviation = 3, the coefficient of variation CV is calculated to be 0.25. The determination process of earthquake or noise using the coefficient of variation will be described in detail later.

[0049] The earthquake determination unit 26 determines whether the detected vibration is an earthquake or noise according to the determination result of whether there is variation in the total change amount variation determination unit 25. Specifically, when the earthquake determination unit 26 determines that the variation in the total change amount variation determination unit 25 is smaller than a predetermined threshold, the detected vibration is determined to be noise. On the other hand, when the earthquake determination unit 26 determines that the variation in the total change amount variation determination unit 25 is equal to or greater than a predetermined threshold, the detected vibration is determined to be an earthquake.

[0050] When the earthquake determination unit 26 determines that it is an earthquake, the earthquake magnitude calculation unit 27 determines whether it is an earthquake of a certain seismic intensity or higher. Also, when the detected vibration is determined to be an earthquake and the calculation of an index indicating the magnitude of the earthquake starts, and then a vibration that can be regarded as noise such as an impact is detected, the earthquake magnitude calculation unit 27 excludes the vibration and calculates the earthquake magnitude.

[0051] The output control unit 28 controls the output of a signal from the output unit 14, which outputs a predetermined signal, depending on whether the magnitude of the earthquake calculated by the earthquake magnitude calculation unit 27 is equal to or greater than a predetermined seismic intensity. Here, the predetermined signal output from the output unit 14 includes, for example, a shutoff signal that is transmitted to external equipment such as an electricity supply device or a gas supply device in order to stop the supply of energy such as electricity or gas. The storage unit 30 stores, for example, the acceleration data acquired by the acceleration acquisition unit 21, the judgment results from the total change amount dispersion determination unit 25 and the earthquake determination unit 26, etc.

[0052] <Earthquake Detection Method> The earthquake detection method using the seismic sensor 10 of this embodiment will be explained below using the flowchart shown in Figure 6.

[0053] Specifically, in step S11, the acceleration acquisition unit 21 of the seismic sensor 10 acquires the acceleration measured by the acceleration sensor 11. Next, in step S12, the acceleration waveform generation unit 22 generates an acceleration waveform from the acceleration acquired in step S11. Next, in step S13, the total speed change calculation unit 24 adds the absolute value of the acceleration to the integrated value s(i) (i = 0, 1, 2).

[0054] Next, in step S14, the total change amount variation determination unit 25 determines whether a certain time (for example, 1 second) has elapsed. If a certain time has elapsed, the process proceeds to step S15; otherwise, the process returns to step S11 and repeats. Next, in step S15, since it was determined in step S14 that a certain time had elapsed, the total change amount variation determination unit 25 buffers the sum of the accumulated values ​​s(0) to s(2) as the total change amount of speed over a certain interval.

[0055] Next, in step S16, the total change amount variation determination unit 25 sets i to i+1 and takes the remainder when divided by 3. Next, in step S17, s(i) is cleared to zero. Next, in step S18, the total change amount variation determination unit 25 determines whether the vibration determination has been completed or not.

[0056] If the vibration determination is completed at this point, the process proceeds to step S19. If the vibration determination is not completed, the process returns to step S11 and repeats. Next, in step S19, since it was determined in step S18 that the vibration determination was completed, the total change amount variation determination unit 25 calculates the coefficient of variation from the total change amount of speed over a buffered fixed section.

[0057] Next, in step S20, the total variation variation determination unit 25 determines whether the coefficient of variation calculated in step S19 is smaller than a predetermined threshold. If the coefficient of variation is smaller than the predetermined threshold, the process proceeds to step S21; if the coefficient of variation is greater than or equal to the predetermined threshold, the process proceeds to step S22. Next, in step S21, the earthquake determination unit 26 determines, based on the determination result in step S20, that the detected vibration is noise and terminates the process. On the other hand, in step S22, the earthquake determination unit 26 determines, based on the determination result in step S20, that the detected vibration is an earthquake and terminates the process.

[0058] <Main Features> The seismic sensor 10 of this embodiment includes an acceleration acquisition unit 21, a total speed change calculation unit 24, a total change variation determination unit 25, and an earthquake determination unit 26. The acceleration acquisition unit 21 acquires the acceleration of the vibration. The total speed change calculation unit 24 calculates the total speed change over a predetermined fixed period based on the acceleration acquired by the acceleration acquisition unit 21. The total change variation determination unit 25 determines whether there is variation in the total speed change calculated by the total speed change calculation unit 24 for each of a plurality of predetermined fixed periods. The earthquake determination unit 26 determines whether the vibration is an earthquake or not based on the determination result of the total change variation determination unit 25 regarding the presence or absence of variation. As a result, by determining whether the detected vibration is an earthquake or noise based on the variation in the total speed change over a predetermined fixed period from the acceleration of the detected vibration, it is possible to detect vibrations with a nearly constant force applied as noise without misidentifying them as earthquakes. As a result, it is possible to accurately determine whether the detected vibration is an earthquake or noise.

[0059] [Other Embodiments] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the invention.

[0060] (A) In the above embodiments, the present invention was described using examples of the seismic sensor 10 and the earthquake determination method. However, the present invention is not limited thereto. For example, the present invention may be implemented as an earthquake determination program that causes a computer to execute the earthquake determination method using the seismic sensor described above.

[0061] This earthquake detection program is stored in the memory (storage unit) installed in the seismic sensor, and the CPU reads the earthquake detection program stored in the memory and causes the hardware to execute each step. More specifically, the same effect as above can be obtained by the CPU reading the earthquake detection program and executing the steps described above. Furthermore, the present invention may be implemented as a recording medium that stores the earthquake detection program of the seismic sensor.

[0062] (B) In the above embodiment, an example was given in which the acceleration waveform generation unit 22 generates the acceleration waveform shown in Figure 3(a) from the detected vibration acceleration. However, the present invention is not limited thereto. For example, if the total change in speed is calculated directly by integrating the absolute value of the acceleration without generating an acceleration waveform, the seismic sensor may not have an acceleration waveform generation unit.

[0063] (C) In the above embodiment, an example was given in which the earthquake determination unit 26 uses the coefficient of variation as an index indicating the variation in the total change in speed over a certain period when determining whether an earthquake or noise is present. However, the present invention is not limited thereto. For example, instead of the coefficient of variation, the earthquake determination unit may use other numerical values ​​such as variance or standard deviation as an index indicating the variation in the total change in speed over a certain period when determining whether an earthquake or noise is present.

[0064] (D) In ​​the above embodiment, an example was given in which the total change in speed is calculated by taking the sum of three cumulative values ​​as the total change in speed. However, the present invention is not limited to this. For example, the number of cumulative values ​​to be added is not limited to three, but can be any number. Alternatively, instead of taking the sum, the average value may be used as the total change in speed.

[0065] (E) In the above embodiment, an example was described in which the storage unit 30 for storing earthquake judgment results, etc., is provided inside the seismic sensor 10. However, the present invention is not limited thereto. For example, the storage unit for storing earthquake judgment results, etc., may be provided in an external server such as a cloud server.

[0066] <Note> The seismic sensor according to the first invention comprises: an acceleration acquisition unit for acquiring the acceleration of vibration; a total speed change calculation unit for calculating the total speed change over a predetermined fixed section based on the acceleration acquired by the acceleration acquisition unit; a total change variation determination unit for determining whether or not there is variation in the total speed change calculated by the total speed change calculation unit in each of the plurality of predetermined fixed sections; and an earthquake determination unit for determining whether or not the vibration is an earthquake based on the determination result of the total change variation determination unit for the presence or absence of variation.

[0067] The seismic sensor according to the second invention is the seismic sensor according to the first invention, wherein the total speed change calculation unit calculates the total speed change by integrating the absolute value of the acceleration over the specified interval. The seismic sensor according to the third invention is the seismic sensor according to the first or second invention, wherein the earthquake determination unit determines that the variation is smaller than a predetermined threshold in the total change variation determination unit, and determines the vibration as noise.

[0068] The seismic sensor according to the fourth invention is a seismic sensor according to any one of the first to third inventions, wherein the earthquake determination unit determines that the vibration is an earthquake when the total change variation determination unit determines that the variation is greater than or equal to a predetermined threshold. The seismic sensor according to the fifth invention is a seismic sensor according to any one of the first to fourth inventions, further comprising an acceleration waveform generation unit that generates an acceleration waveform showing the relationship between the acceleration measured in the acceleration acquisition unit and the elapsed time, wherein the total speed change calculation unit calculates the total speed change from the acceleration waveform generated in the acceleration waveform generation unit.

[0069] The earthquake sensor according to the sixth invention is an earthquake sensor according to any one of the first to fifth inventions, further comprising an earthquake magnitude calculation unit that determines whether or not an earthquake is of a predetermined seismic intensity or greater when the earthquake determination unit determines that an earthquake has occurred. The earthquake sensor according to the seventh invention is an earthquake sensor according to any one of the first to sixth inventions, further comprising a startup determination unit that calculates the intensity of the vibration from the measurement results in the acceleration acquisition unit, and switches from a power-saving mode to a measurement mode that consumes more power than the power-saving mode when the intensity of the vibration is greater than or equal to a predetermined magnitude.

[0070] The seismic sensor according to the eighth invention is a seismic sensor according to any one of the first to seventh inventions, further comprising an output control unit that outputs a predetermined signal when the earthquake determination unit determines that an earthquake has occurred. The seismic sensor according to the ninth invention is a seismic sensor according to any one of the first to eighth inventions, further comprising a storage unit that stores the determination results in the total change variation determination unit and the earthquake determination unit.

[0071] The seismic sensor of the present invention has the effect of being able to accurately determine whether the detected vibration is an earthquake or noise, and therefore can be widely applied to sensors that detect various types of vibrations.

[0072] 10. Earthquake sensor 11. Acceleration sensor 12. Controller 13. Memory 14. Output unit 21. Acceleration acquisition unit 22. Acceleration waveform generation unit 23. Vibration intensity classification / startup determination unit 24. Total speed change calculation unit 25. Total change variation determination unit 26. Earthquake determination unit 27. Earthquake magnitude calculation unit 28. Output control unit 30. Memory unit

Claims

1. An earthquake sensor comprising: an acceleration acquisition unit for acquiring the acceleration of vibration; a total speed change calculation unit for calculating the total speed change over a predetermined fixed section based on the acceleration acquired by the acceleration acquisition unit; a total change variation determination unit for determining whether or not there is variation in the total speed change calculated by the total speed change calculation unit in each of the plurality of predetermined fixed sections; and an earthquake determination unit for determining whether or not the vibration is an earthquake based on the determination result of the total change variation determination unit for the presence or absence of variation.

2. The seismic sensor according to claim 1, wherein the total speed change calculation unit calculates the total speed change by integrating the absolute value of the acceleration over the specified interval.

3. The earthquake detection unit determines that the vibration is noise when the total change variation determination unit determines that the variation is smaller than a predetermined threshold, according to claim 1 or 2.

4. The earthquake detection unit determines that the vibration is an earthquake when the total change variation determination unit determines that the variation is greater than or equal to a predetermined threshold, as described in claim 1 or 2.

5. The seismic sensor according to claim 1 or 2, further comprising an acceleration waveform generation unit that generates an acceleration waveform showing the relationship between the acceleration measured in the acceleration acquisition unit and the elapsed time, wherein the total speed change calculation unit calculates the total speed change from the acceleration waveform generated in the acceleration waveform generation unit.

6. The earthquake sensor according to claim 1 or 2, further comprising an earthquake magnitude calculation unit that determines whether or not an earthquake is of a predetermined seismic intensity or higher when the earthquake determination unit determines that an earthquake has occurred.

7. The seismic sensor according to claim 1 or 2, further comprising a startup determination unit that calculates the intensity of the vibration from the measurement results in the acceleration acquisition unit, and, if the intensity of the vibration is greater than or equal to a predetermined magnitude, switches from a power-saving mode to a measurement mode which consumes more power than the power-saving mode.

8. The earthquake sensor according to claim 1 or 2, further comprising an output control unit that outputs a predetermined signal when the earthquake determination unit determines that an earthquake has occurred.

9. The seismic sensor according to claim 1 or 2, further comprising a storage unit for storing the determination results in the total change variation determination unit and the earthquake determination unit.

10. An earthquake determination method comprising: obtaining the acceleration of vibration; calculating the total change in velocity over a certain period from the acquired acceleration from the onset to the end of vibration; determining whether or not there is variation in the calculated total change in velocity; and determining whether or not the vibration is an earthquake according to the result of the determination of whether or not there is variation.

11. An earthquake determination program that causes a computer to execute an earthquake determination method, which involves acquiring the acceleration of vibration, calculating the total change in velocity over a certain period from the acquired acceleration from the start to the end of the vibration, determining whether or not there is variation in the calculated total change in velocity, and determining whether or not the vibration is an earthquake according to the result of the determination of whether or not there is variation.

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