Seismic sensor, earthquake detection method, and earthquake detection program

Abstract

To provide a seismic sensor, an earthquake detection method, and an earthquake detection program that can accurately determine if a detected vibration is an earthquake or noise.SOLUTION: A seismic sensor 10 comprises an acceleration acquisition unit 21, an acceleration waveform generation unit 22, a frequency detection unit 24, an increase / decrease ratio calculation unit 25a, an increase / decrease determination unit 25b, and an earthquake determination unit 26. The frequency detection unit 24 detects a frequency and amplitude of an acceleration waveform generated by the acceleration waveform generation unit 22. The increase / decrease ratio calculation unit 25a calculates, on the basis of the frequency and amplitude detected by the frequency detection unit 24, an increase / decrease ratio from the frequency and amplitude of the acceleration waveform previously detected by the frequency detection unit 24. The increase / decrease determination unit 25b compares the increase / decrease ratio calculated by the increase / decrease ratio calculation unit 25a with a predetermined threshold to determine whether a vibration is amplification or attenuation. The earthquake determination unit 26 determines whether or not the vibration is an earthquake on the basis of a result of determination made by the increase / decrease determination unit 25b.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] In recent years, seismic sensors have been used that are built into gas meters, electricity meters, distribution boards, outlets, etc., and that output a cut-off signal to cut off the supply of gas, electricity, etc. when they detect earthquake motion of a magnitude above a predetermined value (for example, seismic intensity 5 or higher). For example, Patent Document 1 discloses a seismic sensor that outputs a shutoff signal when an index value indicating the magnitude of an earthquake is equal to or greater than a threshold value during an earthquake processing period following a judgment period, and that includes a continuing earthquake judgment unit that judges whether an earthquake has occurred based on the acceleration measured during the earthquake processing period, and a shutoff judgment unit that prevents the shutoff signal from being output regardless of the index value when the continuing earthquake judgment unit judges that an earthquake has not occurred. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6465257 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned conventional seismic sensors have the following problems. In other words, the seismic sensor disclosed in the above publication determines whether vibration has stopped based solely on acceleration, so if the peak-peak value of acceleration over a certain period of time is monotonically attenuated from the previous value, it is determined to be noise. Compared to low-frequency vibrations, high-frequency vibrations tend to produce large changes in acceleration with small changes in displacement, and everyday vibrations (noise) are often high-frequency vibrations. For this reason, high-frequency vibrations (noise) often do not decay monotonically, which can lead to the risk of misidentifying everyday vibrations as earthquakes.

[0005] An object of the present invention is to provide a seismic sensor, an earthquake detection method, and an earthquake detection program that can determine with high accuracy whether detected vibrations are earthquakes or noise. [Means for solving the problem]

[0006] The seismic sensor according to the first aspect of the present invention includes an acceleration acquisition unit, an acceleration waveform generation unit, a detection unit, an increase / decrease rate calculation unit, an increase / decrease determination unit, and an earthquake determination unit. The acceleration acquisition unit detects vibrations and acquires the acceleration of the vibrations. The acceleration waveform generation unit generates an acceleration waveform indicating the relationship between the acceleration measured by the acceleration acquisition unit and elapsed time. The detection unit detects the period and amplitude of the acceleration waveform generated by the acceleration waveform generation unit. The increase / decrease rate calculation unit calculates the rate of increase / decrease from the period and amplitude of the acceleration waveform previously detected by the detection unit based on the period and amplitude detected by the detection unit. The increase / decrease determination unit compares the rate of increase / decrease calculated by the increase / decrease rate calculation unit with a predetermined amplification rate threshold and / or attenuation rate threshold to determine whether the vibration is amplified or attenuated. The earthquake determination unit determines whether the vibration is an earthquake based on the determination result of the increase / decrease determination unit.

[0007] Here, in order to detect noise characteristics such as "monotonous decay" and "no change in rate of increase or decrease" and make an earthquake judgment, the period and amplitude of the acceleration waveform are detected, and the rate of increase or decrease is used to determine whether the signal is amplified or attenuated, and the earthquake judgment is made based on the results. Here, the period and amplitude of the acceleration waveform detected by the detection unit last time refer to the period and amplitude detected in the immediately previous period.

[0008] This allows the system to determine whether the detected vibrations are "monotonically decaying" or have "an almost constant rate of increase or decrease," which are characteristics of noise, using the period and amplitude of the acceleration waveform, and to determine that other vibrations are earthquakes. As a result, it is possible to determine with high accuracy whether the detected vibration is an earthquake or noise.

[0009] The seismic sensor of the second invention is the seismic sensor of the first invention, wherein the increase / decrease determination unit determines whether there is amplification or attenuation by changing the increase / decrease rate threshold or the attenuation rate threshold for determining whether there is amplification or attenuation based on the period detected by the detection unit. This allows for changing the threshold value used to determine whether the vibration is increasing or decreasing in accordance with changes in the period (frequency) of the acceleration waveform of the detected vibration, thereby eliminating the problem of high-frequency vibrations, which tend to have large changes in acceleration, being judged as amplified or attenuated, and enabling more accurate earthquake detection.

[0010] The seismic sensor of the third invention is a seismic sensor of the first or second invention, wherein the earthquake determination unit determines that the vibration is an earthquake if the period in which the increase / decrease determination unit determines that the vibration is attenuating does not continue for a predetermined period. This allows the system to determine that a period of what appears to be monotonous decay, which is characteristic of noise such as high-frequency vibration, continues for a predetermined period of time, and that the vibration is noise, and if it does not continue, that the vibration is determined to be an earthquake.

[0011] The seismic sensor of the fourth invention is a seismic sensor of the first or second invention, wherein the earthquake determination unit determines that the vibration is an earthquake if the period in which the increase / decrease determination unit determines that there is no change in the rate of increase / decrease does not continue for a predetermined period. This allows the vibration to be determined as noise if the rate of increase or decrease, which is characteristic of noise such as high-frequency vibration, does not change for a predetermined period of time, and if it does not continue, the vibration can be determined as an earthquake.

[0012] The seismic sensor of the fifth invention is the seismic sensor of the first or second invention, wherein the detection unit detects the period and amplitude of the acceleration waveform generated by the acceleration waveform generation unit using a zero-crossing method. Here, the zero-crossing method is a method of detecting one cycle (frequency) between the point where a waveform exceeds zero (or a hysteresis set near zero), then falls below zero (a hysteresis value below zero), and then exceeds zero (or a hysteresis set near zero).

[0013] This makes it more difficult to detect minute vibrations compared to the peak method, which detects the time between peaks in the acceleration waveform as one cycle, but it allows for highly accurate detection of the cycle and amplitude without being affected by minute vibration noise.

[0014] The seismic sensor of the sixth invention is a seismic sensor of the first or second invention, and further comprises an earthquake magnitude calculation unit that, when the earthquake determination unit determines that an earthquake has occurred, determines whether the earthquake is of a predetermined seismic intensity or greater. This allows for, for example, if the magnitude of the earthquake is judged to be upper 5 or higher on the seismic intensity scale, there is a risk of fire or gas leaks, and a shut-off signal can be output to stop the supply of energy such as electricity or gas, thereby improving the safety of users.

[0015] The seismic sensor of the seventh invention is a seismic sensor of the first or second invention, and further includes an activation determination unit that calculates the vibration intensity from the measurement results of the acceleration acquisition unit, and when the vibration intensity is equal to or greater than a predetermined magnitude, transitions from a power saving mode to a measurement mode that consumes more power than the power saving mode. This allows the device to switch to a measurement mode that performs earthquake detection processing using the vibration acceleration waveform only when the strength of the detected vibration is equal to or greater than a predetermined magnitude (e.g., equivalent to a seismic intensity of 4), thereby enabling highly accurate earthquake detection while reducing power consumption.

[0016] The seismic sensor of the eighth invention is a seismic sensor of the first or second invention, further comprising an output control unit that outputs a predetermined signal when the earthquake determination unit determines that an earthquake has occurred. This allows, for example, when an earthquake occurs, the output unit to output a cutoff signal to stop the supply of energy such as electricity or gas, or a warning signal to warn of danger.

[0017] The seismic sensor of the ninth invention is a seismic sensor of the first or second invention, further comprising a memory unit that stores a table showing the relationship between the period and an amplification factor threshold or attenuation factor threshold that changes based on the recording period. This allows earthquake determination to be performed by referring to a table stored in the storage unit that shows the relationship between the amplification factor threshold value, the attenuation factor threshold value, and the period.

[0018] An earthquake detection method according to a tenth aspect of the present invention includes an acceleration acquisition step, an acceleration waveform generation step, a detection step, an increase / decrease rate calculation step, an increase / decrease determination step, and an earthquake determination step. In the acceleration acquisition step, vibrations are detected and the acceleration of the vibrations is acquired. In the acceleration waveform generation step, an acceleration waveform indicating the relationship between the acceleration measured in the acceleration acquisition step and elapsed time is generated. In the detection step, the period and amplitude of the acceleration waveform generated in the acceleration waveform generation step are detected. In the increase / decrease rate calculation step, an increase / decrease rate from the period and amplitude of the acceleration waveform previously detected in the detection step is calculated based on the period and amplitude detected in the detection step. In the increase / decrease determination step, the increase / decrease rate calculated in the increase / decrease rate calculation step is compared with a predetermined amplification rate threshold and / or attenuation rate threshold to determine whether the vibration is amplified or attenuated. In the earthquake determination step, it is determined whether the vibration is an earthquake based on the determination result in the increase / decrease determination step. Here, in order to detect noise characteristics such as "monotonous decay" and "no change in rate of increase or decrease" and make an earthquake judgment, the period and amplitude of the acceleration waveform are detected, and the rate of increase or decrease is used to determine whether the signal is amplified or attenuated, and the earthquake judgment is made based on the results.

[0019] Here, the period and amplitude of the acceleration waveform detected by the detection unit last time refer to the period and amplitude detected in the immediately previous period. This allows the system to determine whether the detected vibrations are "monotonically decaying" or have "an almost constant rate of increase or decrease," which are characteristics of noise, using the period and amplitude of the acceleration waveform, and to determine that other vibrations are earthquakes. As a result, it is possible to determine with high accuracy whether the detected vibration is an earthquake or noise.

[0020] An eleventh aspect of the present invention provides an earthquake detection program that causes a computer to execute an earthquake detection method including an acceleration acquisition step, an acceleration waveform generation step, a detection step, an increase / decrease rate calculation step, an increase / decrease determination step, and an earthquake determination step. In the acceleration acquisition step, vibrations are detected and the acceleration of the vibrations is acquired. In the acceleration waveform generation step, an acceleration waveform indicating the relationship between the acceleration measured in the acceleration acquisition step and elapsed time is generated. In the detection step, the period and amplitude of the acceleration waveform generated in the acceleration waveform generation step are detected. In the increase / decrease rate calculation step, an increase / decrease rate from the period and amplitude of the acceleration waveform previously detected in the detection step is calculated based on the period and amplitude detected in the detection step. In the increase / decrease determination step, the increase / decrease rate calculated in the increase / decrease rate calculation step is compared with a predetermined amplification rate threshold and / or attenuation rate threshold to determine whether the vibration is amplified or attenuated. In the earthquake determination step, it is determined whether the vibration is an earthquake based on the determination result in the increase / decrease determination step.

[0021] Here, in order to detect noise characteristics such as "monotonous decay" and "no change in rate of increase or decrease" and make an earthquake judgment, the period and amplitude of the acceleration waveform are detected, and the rate of increase or decrease is used to determine whether the signal is amplified or attenuated, and the earthquake judgment is made based on the results. Here, the period and amplitude of the acceleration waveform detected by the detection unit last time refer to the period and amplitude detected in the immediately previous period.

[0022] This allows the system to use the period and amplitude of the acceleration waveform to determine whether the detected vibrations exhibit "monotonically decaying" or "almost constant rate of increase or decrease," which are characteristics of noise, and to determine that other vibrations are earthquakes. As a result, it is possible to determine with high accuracy whether the detected vibration is an earthquake or noise.

[0023] A seismic sensor according to a twelfth aspect of the present invention includes an acceleration acquisition unit, an acceleration waveform generation unit, a detection unit, an increase / decrease rate calculation unit, and an increase / decrease determination unit. The acceleration acquisition unit detects vibrations and acquires the acceleration of the vibrations. The acceleration waveform generation unit generates an acceleration waveform indicating the relationship between the acceleration measured by the acceleration acquisition unit and elapsed time. The detection unit detects the period and amplitude of the acceleration waveform generated by the acceleration waveform generation unit. The increase / decrease rate calculation unit calculates the rate of increase / decrease from the period and amplitude of the acceleration waveform previously detected by the detection unit based on the period and amplitude detected by the detection unit. The increase / decrease determination unit compares the rate of increase / decrease calculated by the increase / decrease rate calculation unit with a predetermined amplification rate threshold and / or attenuation rate threshold to determine whether the vibration is amplified or attenuated.

[0024] Here, vibration analysis is performed to detect noise characteristics such as "monotonous decay" and "no change in rate of increase or decrease" to determine whether an earthquake is occurring. The period and amplitude of the acceleration waveform are detected, and the rate of increase or decrease is used to determine whether the waveform is amplified or attenuated. Here, the period and amplitude of the acceleration waveform detected by the detection unit last time refer to the period and amplitude detected in the immediately previous period.

[0025] This allows the system to use the period and amplitude of the acceleration waveform to determine whether the detected vibrations exhibit "monotonically decaying" or "almost constant rate of increase or decrease," which are characteristics of noise, and to determine that other vibrations are earthquakes. As a result, it is possible to determine with high accuracy whether the detected vibration is an earthquake or noise. [Effects of the Invention]

[0026] The seismic sensor according to the present invention can determine with high accuracy when high frequency vibrations such as those caused by daily life have stopped. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a control block diagram showing the configuration of a seismic sensor according to an embodiment of the present invention. [Figure 2] Functional block diagram generated within the seismic sensor in Figure 1. [Figure 3] 6 is a graph illustrating a zero-crossing method for detecting the frequency of an acceleration waveform of detected vibration. [Figure 4] (a) is a graph showing the change in the amplitude of displacement versus the period of the displacement, which is used to determine whether the vibration is amplifying or attenuating based on the current amplitude of the displacement. (b) is a graph showing the change in the amplitude of acceleration versus the period of the acceleration obtained by differentiating (a) twice. [Figure 5] 4(b) is a graph showing the relationship (table) of the increase / decrease rate threshold for determining an increase / decrease with respect to the period of acceleration obtained by differentiating the graph of FIG. 4(a) twice. [Figure 6] 3 is a flowchart showing the flow of processing in an earthquake detection method executed by the seismic sensor of FIG. 2; DETAILED DESCRIPTION OF THE INVENTION

[0028] A seismic sensor according to one embodiment of the present invention will be described below with reference to FIGS. 1 to 6. FIG. In the present embodiment, more detailed explanation than necessary may be omitted. For example, detailed explanation of well-known matters or redundant explanation of substantially the same configuration may be omitted. This is to avoid unnecessary redundancy in the following explanation and to facilitate understanding by those skilled in the art.

[0029] Furthermore, the applicant provides the accompanying drawings and the following description to enable those skilled in the art to fully understand the present invention, and they are not intended to limit the subject matter described in the claims.

[0030] (1) Configuration of the seismic sensor 10 As shown in FIG. 1, the seismic sensor 10 according to this embodiment includes an acceleration sensor 11, a controller 12, and a memory 13. The acceleration sensor 11 is, for example, an acceleration sensor using a piezoelectric element or an acceleration sensor that detects electrostatic 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, detects the occurrence of an earthquake based on the acquired acceleration, and calculates an index value indicating the magnitude of the earthquake.

[0031] Also, the controller 12 operates in different modes, active mode or sleep mode, depending on the situation. The sleep mode is a mode in which the controller 12 operates with limited functions, such as stopping the execution of instructions while accepting interrupts, stopping the supply of clocks, etc. In this sleep mode, power consumption can be reduced more than in the active mode.

[0032] The active mode is a mode in which a process is performed to determine whether the detected vibration is an earthquake or noise, and an index value indicating the magnitude of the earthquake is calculated. The function blocks (see FIG. 2) generated when the CPU in the seismic sensor 10 reads the earthquake detection program stored in the memory 13 will be described in detail later. The memory 13 is a temporary storage means such as a RAM (Random Access Memory) or a non-volatile memory such as an EPROM (Erasable Programmable Read Only Memory), and stores, for example, the acceleration measured by the acceleration sensor 11 and threshold values ​​used for earthquake determination.

[0033] 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 included in the controller 12, and when the controller 12 determines that, for example, an earthquake has occurred, information indicating the occurrence and scale of the earthquake is output to another device via the output unit 14. Furthermore, when an earthquake of a predetermined scale or greater is detected, the output unit 14 outputs, for example, a cutoff signal to an external device to stop the supply of energy such as electricity or gas.

[0034] (2) Functional block of 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 discrimination / activation determination unit 23, a frequency detection unit 24, an increase / decrease rate calculation unit 25a, an increase / decrease determination unit 25b, an earthquake determination unit 26, an earthquake magnitude calculation unit 27, an output control unit 28, an offset adjustment unit 29, and a memory unit 30.

[0035] These functional blocks shown in FIG. 2 are configured by the controller 12 receiving acceleration data obtained from the acceleration sensor 11 and reading a program stored in the memory 13. The acceleration acquiring unit 21 acquires measurement data of acceleration measured at a predetermined period by the acceleration sensor 11. Note that the acceleration acquiring unit 21 normally acquires measurement data of acceleration measured repeatedly at a relatively low speed (i.e., at a relatively large measurement period).

[0036] When performing such low-speed acceleration sampling, the controller 12 basically operates in a sleep mode (standby state or power-saving mode) with low power consumption. In the standby state, the acceleration sensor 11 is in an operating state where it samples at a low speed, so the controller 12 operates in a sleep mode with limited functionality, thereby reducing power consumption.

[0037] Furthermore, when the acceleration acquisition unit 21 acquires vibrations greater than a threshold value preset in the storage unit 30, the acceleration sensor 11 repeats measuring the acceleration at a higher speed (i.e., at a relatively short cycle) than during low-speed sampling. During such high-speed sampling, the controller 12 operates in a sleep mode or an active mode. When the earthquake determination unit 26 (described later) and the like execute processing, the controller 12 operates in active mode (measurement mode). The transition from the power saving mode to the measurement mode is called the activation of the seismic sensor 10.

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

[0039] The acceleration waveform generating unit 22 generates an acceleration waveform that indicates the relationship between the acceleration measured by the acceleration acquiring unit 21 and the elapsed time. The vibration intensity discrimination and activation determination unit 23 is a function on the acceleration sensor 11 side, which compares the acceleration value acquired by the acceleration acquisition unit 21 with the activation threshold value stored in the memory unit 30, and if the acceleration value exceeds the activation threshold value, transitions from power saving mode to measurement mode (activates the seismic sensor 10).

[0040] In addition, the vibration intensity discrimination / activation determination unit 23 calculates the vibration intensity from the measurement results of the acceleration acquisition unit 21, and if the vibration intensity is equal to or greater than a predetermined magnitude, transitions from the power saving mode to the measurement mode, which consumes more power than the power saving mode (activates the controller 12). Here, the vibration intensity classification process performed by the vibration intensity classification / activation determination unit 23 is performed by filtering the acceleration value acquired by the acceleration acquisition unit 21. At this time, the filtered acceleration is stored in the storage unit 30.

[0041] The frequency detection section 24 detects the period (frequency) and amplitude of the acceleration waveform generated by the acceleration waveform generation section 22, for example, by a zero-crossing method. The zero-crossing method is a method that detects the time between the point where a waveform crosses zero (or a hysteresis value set near zero) and the next point where it crosses zero (or a hysteresis value set near zero) as one cycle (frequency) (see Figure 3). Compared to the peak method, which detects the time between one waveform peak and the next peak as one cycle, the zero-crossing method makes it more difficult to detect minute vibrations, but it eliminates the effects of noise near zero acceleration (within the hysteresis range) and can detect frequencies with high accuracy without being affected by minute vibration noise around the peak value.

[0042] The width of the hysteresis value that is set in advance when performing detection using the zero-cross method shown in FIG. 3 is adjusted as appropriate depending on the type and magnitude of the vibration to be detected. Based on the period and amplitude of the acceleration waveform detected by frequency detection unit 24, increase / decrease rate calculation unit 25a calculates the rate of increase / decrease from the period and amplitude of the acceleration waveform previously detected by frequency detection unit 24. That is, in order to monitor changes in the period and amplitude of the acceleration waveform, increase / decrease rate calculation unit 25a compares the previous period and amplitude with the current period and amplitude to calculate the rate of increase / decrease (amplification rate, attenuation rate) of the acceleration waveform.

[0043] The increase / decrease determination unit 25b compares the increase / decrease rate calculated by the increase / decrease rate calculation unit 25a with a predetermined amplification rate threshold and / or attenuation rate threshold to determine whether the vibration is amplified, attenuated, or unchanged. That is, as shown in Fig. 4(a), the increase / decrease determination unit 25b sets a region where it is determined to be unchanged, a region where it is determined to be amplified, and a region where it is determined to be attenuated, based on the current amplitude of the displacement. At this time, the amplitude of the acceleration changes depending on the period (frequency), as shown in the graph shown in Fig. 4(b), which is obtained by differentiating the graph shown in Fig. 4(a) twice.

[0044] In the example shown in Figure 4(a), in the region with a short period (high frequency), the amplitude of the displacement is amplified when comparing the previous period (the period immediately preceding) with the current period, but in the example shown in Figure 4(b), the amplitude of the acceleration is attenuated when comparing the previous period with the current period. For this reason, the conventional seismic sensor configuration has the problem of misjudging this as attenuation. In the seismic sensor 10 of this embodiment, the magnitude of the increase / decrease rate threshold (%) is changed with respect to the period of the acceleration waveform to determine whether the amplitude of the acceleration waveform of the detected vibration increases or decreases, as shown in Fig. 5. In the seismic sensor 10, the increase / decrease determination unit 25b sets the threshold for increase / decrease determination to a larger value as the period of the acceleration waveform becomes shorter (the frequency becomes higher), as shown in Fig. 5. On the other hand, the increase / decrease determination unit 25b sets the threshold for increase / decrease determination to a smaller value as the period of the acceleration waveform becomes longer (the frequency becomes lower), as shown in Fig. 5.

[0045] This allows the threshold value used to determine whether the vibration is increased or decreased to be changed according to the change in the period (frequency) of the acceleration waveform of the detected vibration, and by setting a large threshold value for high-frequency vibrations, which tend to have large changes in acceleration, the problem of high-frequency vibrations being easily determined to be amplified or attenuated can be resolved. As a result, for example, by storing the graph (table) shown in Figure 5 in the memory unit 30, the increase / decrease determination unit 25b can make a determination by changing the magnitude of the threshold value for determining increase / decrease depending on the period (frequency) of the detected vibration.

[0046] Here, characteristic features that appear when the detected vibration is noise and not an earthquake include, for example, a "monotonically decaying" rate of increase or decrease in the amplitude of the acceleration waveform, or "the rate of increase or decrease hardly changes." Specifically, earthquake vibrations are characterized by constantly vibrating in various directions, not decaying monotonically, and the rate of increase or decrease changing easily. On the other hand, vibrations caused by noise, such as those from everyday life, tend to decay monotonically and generally show almost no change in the rate of increase or decrease.

[0047] Therefore, the seismic sensor 10 of this embodiment detects that vibrations other than earthquakes (noises such as everyday vibrations) tend to decay monotonically and that the rate of increase or decrease hardly changes, and thereby determines that other vibrations are earthquakes. The earthquake determination unit 26 determines whether or not the vibration is an earthquake based on the period and amplitude detected by the frequency detection unit 24 and the result of the determination by the increase / decrease determination unit 25b.

[0048] Specifically, if the period during which the increase / decrease determination unit 25b has determined that the vibration is attenuating does not continue for a predetermined period, the earthquake determination unit 26 determines that the vibration is an earthquake. In other words, if the period during which the increase / decrease determination unit 25b has determined that the vibration is attenuating continues for a predetermined period, the earthquake determination unit 26 determines that the vibration is monotonically attenuating and determines that it is noise. Furthermore, if the period during which the increase / decrease determination unit 25b has determined that the rate of increase / decrease is unchanged does not continue for a predetermined period, the earthquake determination unit 26 determines that the vibration is an earthquake. In other words, if the period during which the increase / decrease determination unit 25b has determined that the rate of increase / decrease is unchanged continues for a predetermined period, the earthquake determination unit 26 determines that the vibration exhibits the characteristics of noise and determines that the vibration is an earthquake.

[0049] When the earthquake determination unit 26 determines that an earthquake has occurred, the earthquake magnitude calculation unit 27 determines whether the earthquake has a seismic intensity of at least a predetermined level. Furthermore, after the earthquake magnitude calculation unit 27 determines that the detected vibration is an earthquake and starts calculating an index indicating the magnitude of the earthquake, if an acceleration waveform that can be considered to be an impact is detected, the earthquake magnitude calculation unit 27 excludes the acceleration waveform and calculates the magnitude of the earthquake.

[0050] 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 sent to an external device such as an electricity supply device or a gas supply device in order to stop the supply of energy such as electricity or gas.

[0051] When earthquake determination unit 26 determines that the vibration detected by acceleration acquisition unit 21 is noise, offset adjustment unit 29 adjusts the offset amount of the acceleration waveform according to the magnitude of the noise. Then, offset adjustment unit 29 adjusts the offset amount of the acceleration waveform according to the determination result of earthquake determination unit 26 made based on the acceleration waveform. The offset adjustment performed by the offset adjuster 29 detects noise components contained in the measured acceleration as offset components, such as the amount of change in the measurement value that occurs with changes over time in the seismic sensor 10, the amount of change in the measurement value that occurs with temperature changes, and the amount of change in the measurement value that occurs when the orientation of the installed seismic sensor 10 tilts for some reason and the direction of gravitational acceleration relative to the seismic sensor 10 changes. Specifically, the offset adjuster 29 calculates, for example, the median of the maximum and minimum values ​​of the acceleration determined to be noise, or the average value of the acceleration, as the offset component.

[0052] The memory unit 30 stores, for example, acceleration data acquired by the acceleration acquisition unit 21, or acceleration data after filtering processing, a graph (table) of thresholds used for increase / decrease determination in the increase / decrease determination unit 25b (see Figure 5), the determination results in the earthquake determination unit 26, data on offset components used in the offset adjustment unit 29, etc.

[0053] <Earthquake detection method> The earthquake detection method using the seismic sensor 10 of this embodiment will be described below with reference to the flowchart shown in FIG. That is, 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 generating unit 22 generates an acceleration waveform using the acceleration acquired in step S11. Next, in step S13, the frequency detection unit 24 detects the period and amplitude of the acceleration waveform of the current period generated in step S12 using the zero-crossing method.

[0054] Next, in step S14, the frequency detection unit 24 detects the period and amplitude of the acceleration waveform of the immediately previous period (previous period) generated in step S12 using the zero-crossing method. Next, in step S15, the increase / decrease rate calculation unit 25a acquires thresholds (amplification rate threshold, attenuation rate threshold (see Figure 5)) for determining an increase / decrease in the amplitude of the acceleration waveform that changes depending on the period (frequency) of the acceleration waveform of the previous period detected in step S14, from a graph (table) (see Figure 5) stored in the memory unit 30.

[0055] At this time, the threshold values ​​(amplification rate threshold, attenuation rate threshold) acquired for determining increase or decrease are set larger as the period of the acceleration waveform becomes shorter (high frequency), and are set smaller as the period of the acceleration waveform becomes longer (low frequency), as described above. Next, in step S16, the increase / decrease rate calculation unit 25a calculates the increase / decrease rate based on the amplitude of the acceleration waveform in the previous cycle (the cycle immediately preceding) and the amplitude of the acceleration waveform in the current cycle.

[0056] Next, in step S17, increase / decrease determination unit 25b determines whether the rate of increase / decrease calculated in step S16 is greater than the amplification factor threshold for increase / decrease determination obtained from the graph (table) shown in Fig. 5. If it is determined that the rate of increase / decrease is greater than the amplification factor threshold, the process proceeds to step S18, and if it is determined that the rate of increase / decrease is equal to or less than the amplification factor threshold, the process proceeds to step S19.

[0057] Next, in step S18, since it is determined in step S17 that the rate of increase or decrease is greater than the amplification rate threshold, the increase or decrease determining unit 25b determines that the vibration is amplified. Next, in step S19, the earthquake determination unit 26 determines whether amplification has continued for a certain period of time. If amplification has continued for a certain period of time, it is determined that the vibration has the characteristics of an earthquake, and step S20 is skipped and the process proceeds to step S21. On the other hand, if amplification has not continued for a certain period of time, the process proceeds to step S20.

[0058] Next, in step S20, since it was determined in step S19 that amplification has not continued for a certain period of time, the earthquake determination unit 26 determines whether or not vibration determination has ended. If it is determined that vibration determination has ended, the process proceeds to step S21, and if it is determined that it has not ended, the process returns to step S11 and the following processing is repeated. Next, in step S21, since it was determined in step S19 that amplification had not continued for a certain period of time and it was determined in step S20 that vibration determination had ended, or it was determined in step S19 that amplification had continued for a certain period of time, the earthquake determination unit 26 determines that the vibration is an earthquake and terminates the processing.

[0059] On the other hand, in step S22, since it was determined in step S17 that the rate of increase or decrease calculated in step S16 was equal to or less than the amplification rate threshold, increase or decrease determination unit 25b determines whether the rate of increase or decrease calculated in step S16 is less than the attenuation rate threshold. If increase or decrease determination unit 25b determines that the amplification rate is less than the attenuation rate threshold, the process proceeds to step S23, and if it determines that the amplification rate is equal to or greater than the attenuation rate threshold, the process proceeds to step S24.

[0060] Next, in step S23, since it was determined in step S22 that the rate of increase or decrease is less than the attenuation rate threshold, the increase or decrease determination unit 25b determines that the vibration is attenuating, and the process proceeds to step S25. On the other hand, in step S24, since it is determined in step S17 that the rate of increase or decrease calculated in step S16 is equal to or less than the amplification rate threshold, and it is determined in step S22 that the rate of increase or decrease is equal to or greater than the attenuation rate threshold, the increase or decrease determination unit 25b determines that the value is in the "no change" region between the amplification rate threshold and the attenuation rate threshold shown in FIG. 5.

[0061] Next, in step S25, since earthquake determination unit 26 determined in step S23 that the vibration is attenuating, or determined in step S24 that the rate of increase or decrease of the amplitude of the vibration acceleration waveform is not changing, increase / decrease determination unit 25b determines whether (a) the period of attenuation has continued for a certain period, or (b) the period of no change has continued for a certain period. Here, if condition (a) or (b) is satisfied, the process proceeds to step S28. On the other hand, if condition (a) or (b) is not satisfied, the process proceeds to step S26.

[0062] Next, in step S26, since it was determined in step S25 that the detected vibration was not a vibration that is "monotonically attenuated" or "does not change for a certain period of time" characteristic of noise, the earthquake determination unit 26 determines whether or not the vibration determination has been completed. If it is determined that the vibration determination has been completed, the process proceeds to step S27, and if it is determined that the vibration determination has not been completed, the process returns to step S11 and the following process is repeated.

[0063] Next, in step S27, it is determined that the vibration detected in step S25 is not a vibration that is "monotonically decaying" or "does not change for a certain period of time," which are characteristic of noise, and since it is determined in step S26 that vibration determination has ended, it is determined that the vibration is an earthquake and the process ends. On the other hand, in step S28, since it is determined that the vibration detected in step S25 is a vibration characteristic of noise, the earthquake determination unit 26 determines that the vibration is noise and ends the process.

[0064] <Major features> As shown in FIG. 2, the seismic sensor 10 of this embodiment includes an acceleration acquisition unit 21, an acceleration waveform generation unit 22, a frequency detection unit 24, an increase / decrease rate calculation unit 25a, an increase / decrease determination unit 25b, and an earthquake determination unit 26. The acceleration acquisition unit 21 detects vibrations and acquires the acceleration of the vibrations. The acceleration waveform generation unit 22 generates an acceleration waveform indicating the relationship between the acceleration measured by the acceleration acquisition unit 21 and elapsed time. The frequency detection unit 24 detects the period and amplitude of the acceleration waveform generated by the acceleration waveform generation unit 22. The increase / decrease rate calculation unit 25a calculates the rate of increase / decrease from the period and amplitude of the acceleration waveform previously detected by the frequency detection unit 24, based on the period and amplitude detected by the frequency detection unit 24. The increase / decrease determination unit 25b compares the increase / decrease rate calculated by the increase / decrease rate calculation unit 25a with a predetermined amplification rate threshold and / or attenuation rate threshold to determine whether the vibration is amplified or attenuated. The earthquake determination unit 26 determines whether or not the vibration is an earthquake based on the determination result of the increase / decrease determination unit 25b.

[0065] This allows the system to determine whether the detected vibrations are "monotonically decaying" or have "an almost constant rate of increase or decrease," which are characteristics of noise, using the period and amplitude of the acceleration waveform, and to determine that other vibrations are earthquakes. As a result, it is possible to determine with high accuracy whether the detected vibration is an earthquake or noise.

[0066] [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 gist of the invention. (A) In the above embodiment, the present invention has been described as being implemented as a seismic sensor and an earthquake detection method, but the present invention is not limited to this. For example, the present invention may be realized as an earthquake detection program that causes a computer to execute the earthquake detection method using the seismic sensor described above.

[0067] This earthquake detection program is stored in a 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 CPU reads the earthquake detection program and executes the acceleration acquisition step, acceleration waveform generation step, detection step, increase / decrease rate calculation step, increase / decrease determination step, and earthquake determination step, thereby achieving the same effects as those described above. The present invention may also be realized as a recording medium storing an earthquake detection program.

[0068] (B) In the above embodiment, an example was given in which the period and amplitude of the acceleration waveform are detected to detect noise characteristics such as "monotonically decaying" and "no change in rate of increase or decrease," and any other vibrations are determined to be earthquakes. However, the present invention is not limited to this. For example, the configuration may be such that the period and amplitude of the acceleration waveform are detected to detect either "monotonically decaying" or "no change in rate of increase or decrease," which are characteristics of noise, and then an earthquake is determined.

[0069] (C) In the above embodiment, an example has been described in which a threshold value for determining an amplification factor and a threshold value for determining an attenuation factor are used to determine whether the amplitude of the acceleration waveform of the detected vibration is amplified, attenuated, or unchanged. However, the present invention is not limited to this. For example, if it is not determined that there is no change in the amplitude of the acceleration waveform of the detected vibration, only one threshold value for determination may be set and a determination may be made as to whether there is amplification or attenuation.

[0070] (D) In the above embodiment, an example has been described in which the frequency detection unit 24 detects the period and amplitude of the acceleration waveform using the zero-crossing method, but the present invention is not limited to this. For example, instead of the zero-crossing method, the period and amplitude of the acceleration waveform may be detected by FFT (Fast Fourier Transform).

[0071] (E) In the above embodiment, an example has been described in which the seismic sensor 10 includes the earthquake determination unit 26 that determines whether an earthquake has occurred based on the determination result of the increase / decrease determination unit 25b. However, the present invention is not limited to this. For example, the seismic sensor may be configured to perform the processes up to calculating the rate of increase or decrease and determining whether an increase or decrease has occurred, but not to perform the earthquake determination process. In this case, the determination result from the increase / decrease determination unit is transmitted to an external device (for example, an external server device), and the earthquake determination is performed on the external device side, thereby achieving the same effect as above.

[0072] (F) In the above embodiment, an example has been described in which a vibration is determined to be an earthquake when the vibration continues to be amplified for a certain period of time, or when the vibration does not continue to be amplified for a certain period of time, or when the vibration does not continue to be attenuated or unchanged for a certain period of time, and the vibration determination is completed. However, the present invention is not limited to this.

[0073] For example, the ratio of amplification, attenuation, and no change and the maximum number of consecutive times may be recorded until the vibration determination is completed, and then, at the timing when the vibration determination is completed, it may be determined whether it is an earthquake or noise based on the ratio and the maximum number of consecutive times.

[0074] <Additional Notes> The seismic sensor according to the first invention is an acceleration acquisition unit that detects vibration and acquires the acceleration of the vibration; an acceleration waveform generating unit that generates an acceleration waveform indicating a relationship between the acceleration measured by the acceleration acquiring unit and elapsed time; a detection unit that detects the period and amplitude of the acceleration waveform generated by the acceleration waveform generation unit; an increase / decrease rate calculation unit that calculates, based on the period and the amplitude detected by the detection unit, a rate of increase / decrease from the period and the amplitude of the acceleration waveform previously detected by the detection unit; an increase / decrease determination unit that compares the increase / decrease rate calculated by the increase / decrease rate calculation unit with a predetermined amplification rate threshold and / or attenuation rate threshold to determine whether the vibration is amplified or attenuated; an earthquake determination unit that determines whether the vibration is an earthquake based on the determination result of the increase / decrease determination unit; It is equipped with:

[0075] The seismic sensor according to the second invention is the seismic sensor according to the first invention, The increase / decrease determination unit changes the amplification factor threshold or the attenuation factor threshold for determining whether there is an increase / decrease or an attenuation based on the period detected by the detection unit, and determines whether there is an increase or decrease or an attenuation. The seismic sensor according to the third invention is the seismic sensor according to the first or second invention, The earthquake determination unit determines that the vibration is an earthquake when the period during which the increase / decrease determination unit determines that the vibration is attenuating does not continue for a predetermined period.

[0076] A seismic sensor according to a fourth aspect of the present invention is a seismic sensor according to any one of the first to third aspects of the present invention, The earthquake determination unit determines that the vibration is an earthquake when the period during which the increase / decrease determination unit determines that the rate of increase / decrease is unchanged does not continue for a predetermined period. A seismic sensor according to a fifth aspect of the present invention is a seismic sensor according to any one of the first to fourth aspects of the present invention, The detection unit detects the period and amplitude of the acceleration waveform generated by the acceleration waveform generation unit using a zero-crossing method.

[0077] A seismic sensor according to a sixth aspect of the present invention is a seismic sensor according to any one of the first to fifth aspects of the present invention, The earthquake detection unit further includes an earthquake magnitude calculation unit that determines whether the earthquake is equivalent to or greater than a predetermined seismic intensity when the earthquake determination unit determines that an earthquake has occurred. The seismic sensor according to the seventh invention is the seismic sensor according to any one of the first to sixth inventions, The device further includes an activation determination unit that calculates the vibration intensity from the measurement results of the acceleration acquisition unit, and when the vibration intensity is equal to or greater than a predetermined magnitude, transitions from a power saving mode to a measurement mode that consumes more power than the power saving mode.

[0078] The seismic sensor according to an eighth aspect of the present invention is the seismic sensor according to any one of the first to seventh aspects of the present invention, The earthquake detection unit further includes an output control unit that outputs the predetermined signal when it is determined that an earthquake has occurred. A seismic sensor according to a ninth aspect of the present invention is a seismic sensor according to any one of the first to eighth aspects of the present invention, The device further includes a storage unit that stores a table showing the relationship between the period and the amplification factor threshold or the attenuation factor threshold that changes based on the period. [Industrial Applicability]

[0079] The seismic sensor of the present invention has the effect of being able to accurately determine the cessation of high-frequency vibrations, such as those caused by daily life, and is therefore widely applicable to various devices that detect and analyze vibrations. [Explanation of symbols]

[0080] 10 Seismic Sensor 11 Acceleration sensor 12 Controllers 13. Memory 14 Output section 21 Acceleration acquisition section 22 Acceleration waveform generator 23 Vibration intensity classification / startup determination section (startup determination section) 24 Frequency detection unit (detection unit) 25a Increase / decrease rate calculation section 25b Increase / decrease determination section 26 Earthquake Judgment Department 27 Earthquake scale calculation department 28 Output control section 29 Offset adjustment section 30 Storage section

Claims

1. an acceleration acquisition unit that detects vibration and acquires the acceleration of the vibration; an acceleration waveform generating unit that generates an acceleration waveform indicating a relationship between the acceleration measured by the acceleration acquiring unit and elapsed time; a detection unit that detects the period and amplitude of the acceleration waveform generated by the acceleration waveform generation unit; an increase / decrease rate calculation unit that calculates, based on the period and the amplitude detected by the detection unit, a rate of increase / decrease from the period and the amplitude of the acceleration waveform previously detected by the detection unit; an increase / decrease determination unit that compares the increase / decrease rate calculated by the increase / decrease rate calculation unit with a predetermined amplification rate threshold and / or attenuation rate threshold to determine whether the vibration is amplified or attenuated; an earthquake determination unit that determines whether the vibration is an earthquake based on the determination result of the increase / decrease determination unit; A seismic sensor equipped with:

2. the increase / decrease determination unit determines whether the signal is increasing / decreasing or attenuating by changing the amplification factor threshold or the attenuation factor threshold for determining whether the signal is increasing / decreasing or attenuating, based on the period detected by the detection unit. The seismic sensor according to claim 1 .

3. the earthquake determination unit determines that the vibration is an earthquake when the period during which the increase / decrease determination unit determines that the vibration is attenuated does not continue for a predetermined period. The seismic sensor according to claim 1 or 2.

4. the earthquake determination unit determines that the vibration is an earthquake when the period during which the increase / decrease determination unit determines that the increase / decrease rate is unchanged does not continue for a predetermined period. The seismic sensor according to claim 1 or 2.

5. the detection unit detects the period and amplitude of the acceleration waveform generated by the acceleration waveform generation unit using a zero-crossing method. The seismic sensor according to claim 1 or 2.

6. The apparatus further includes an earthquake magnitude calculation unit that, when the earthquake determination unit determines that an earthquake has occurred, determines whether the earthquake has a seismic intensity of at least a predetermined level. The seismic sensor according to claim 1 or 2.

7. The device further includes an activation determination unit that calculates the vibration intensity from the measurement result of the acceleration acquisition unit, and when the vibration intensity is equal to or greater than a predetermined magnitude, transitions from the power saving mode to a measurement mode that consumes more power than the power saving mode. The seismic sensor according to claim 1 or 2.

8. The earthquake detection unit further includes an output control unit that outputs the predetermined signal when the earthquake detection unit determines that an earthquake has occurred. The seismic sensor according to claim 1 or 2.

9. The method further includes a storage unit that stores a table indicating a relationship between the period and the amplification factor threshold or the attenuation factor threshold that changes based on the period. The seismic sensor according to claim 1 or 2.

10. an acceleration acquisition step of detecting vibration and acquiring the acceleration of the vibration; an acceleration waveform generating step of generating an acceleration waveform indicating a relationship between the acceleration measured in the acceleration acquiring step and elapsed time; a detection step of detecting a period and an amplitude of the acceleration waveform generated in the acceleration waveform generation step; an increase / decrease rate calculation step of calculating, based on the period and the amplitude detected in the detection step, a rate of increase / decrease from the period and the amplitude of the acceleration waveform previously detected in the detection step; an increase / decrease determination step of comparing the increase / decrease rate calculated in the increase / decrease rate calculation step with a predetermined amplification rate threshold and / or attenuation rate threshold to determine whether the increase / decrease rate is an amplification or attenuation rate; an earthquake determination step of determining whether the vibration is an earthquake based on a determination result in the increase / decrease determination step; An earthquake detection method comprising:

11. an acceleration acquisition step of detecting vibration and acquiring the acceleration of the vibration; an acceleration waveform generating step of generating an acceleration waveform indicating a relationship between the acceleration measured in the acceleration acquiring step and elapsed time; a detection step of detecting a period and an amplitude of the acceleration waveform generated in the acceleration waveform generation step; an increase / decrease rate calculation step of calculating, based on the period and the amplitude detected in the detection step, a rate of increase / decrease from the period and the amplitude of the acceleration waveform previously detected in the detection step; an increase / decrease determination step of comparing the increase / decrease rate calculated in the increase / decrease rate calculation step with a predetermined amplification rate threshold and / or attenuation rate threshold to determine whether the increase / decrease rate is an amplification or attenuation rate; an earthquake determination step of determining whether the vibration is an earthquake based on a determination result in the increase / decrease determination step; An earthquake detection program that causes a computer to execute an earthquake detection method comprising the steps of:

12. an acceleration acquisition unit that detects vibration and acquires the acceleration of the vibration; an acceleration waveform generating unit that generates an acceleration waveform indicating a relationship between the acceleration measured by the acceleration acquiring unit and elapsed time; a detection unit that detects the period and amplitude of the acceleration waveform generated by the acceleration waveform generation unit; an increase / decrease rate calculation unit that calculates, based on the period and the amplitude detected by the detection unit, a rate of increase / decrease from the period and the amplitude of the acceleration waveform previously detected by the detection unit; an increase / decrease determination unit that compares the increase / decrease rate calculated by the increase / decrease rate calculation unit with a predetermined amplification rate threshold and / or attenuation rate threshold to determine whether the vibration is amplified or attenuated; A seismic sensor equipped with:

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