Seismic sensor, earthquake determination method, and earthquake determination program

Abstract

A seismic sensor (10) comprises an acceleration acquisition unit (21), a rotation direction determination unit (24), and an earthquake determination unit (26). The acceleration acquisition unit (21) acquires the acceleration of vibration. The rotation direction determination unit (24) determines the direction of rotation from the direction of movement of the acceleration acquired by the acceleration acquisition unit (21), in a coordinate plane along the horizontal plane of the acceleration. The earthquake determination unit (26) determines whether the vibration is an earthquake according to the rotation in the rotation direction determined by the rotation direction determination unit (24).

Description

Earthquake sensor, earthquake detection method, and earthquake detection program

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

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

[0003] Patent No. 6465257

[0004] However, the conventional seismic sensors described above have the following problems. Specifically, the seismic sensors disclosed in the above publication were at risk of misidentifying detected vibrations as noise if they had even slight noise characteristics. Furthermore, because the characteristics of the noise changed depending on the device to which the seismic sensor was attached and the installation environment, it was difficult to accurately detect noise, and there was a risk of misidentifying noise as an earthquake.

[0005] The 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 detected vibrations are earthquakes or noise.

[0006] (Means for solving the problem) The seismic sensor according to the first invention comprises an acceleration acquisition unit, a rotation direction determination unit, and an earthquake determination unit. The acceleration acquisition unit detects vibration and acquires the acceleration of the vibration. The rotation direction determination unit determines the rotation direction from the direction of movement of the acceleration in a coordinate plane along the horizontal plane of the acceleration acquired by the acceleration acquisition unit. The earthquake determination unit determines whether the vibration is an earthquake or not according to the rotation in the rotation direction determined by the rotation direction determination unit.

[0007] Here, to avoid misinterpreting a seismic sensor, for example, installed at the tip of a rod-shaped member, as an earthquake if it is rotating due to vibrations other than an earthquake, the system determines whether the detected vibration is an earthquake based on whether or not it is rotating as specified. In this case, the seismic sensor is installed, for example, on energy measuring instruments such as gas or electricity, to shut off the energy supply if an earthquake of a certain 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. Here, if the presence or absence of rotation is determined from the acceleration of the vibration, for example, if the rotation is above a predetermined number of rotations, or if the number of times there was no fluctuation (variation) in the rotation period is greater than a predetermined threshold, it is estimated that the vibration exhibits noise characteristics.

[0009] Conversely, if the presence or absence of rotation is determined from the acceleration of the vibration, for example, if the rotation is below a predetermined number of rotations, or if the number of times there was no fluctuation (variation) in the rotation period is below a predetermined threshold, it is estimated that the vibration exhibits characteristics of an earthquake. This prevents misidentification of vibrations containing a predetermined rotation as an earthquake based solely on the determination of the presence or absence of rotation from the detected vibration acceleration. As a result, 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, wherein the earthquake determination unit determines that the vibration is noise when the continuous rotation in the rotation direction determined by the rotation direction determination unit is equal to or greater than a predetermined number of rotations. By detecting continuous rotation at a predetermined number of rotations or greater that does not appear in the acceleration waveform indicating an earthquake, it is possible to accurately determine that the detected vibration is noise.

[0011] The seismic sensor according to the third invention is the same as the seismic sensor according to the first invention, wherein the earthquake determination unit determines that the vibration is an earthquake when the continuous rotation in the rotation direction determined by the rotation direction determination unit is less than a predetermined number of rotations. In this way, by detecting that the continuous rotation is less than a predetermined number of rotations, it is possible to accurately determine that the detected vibration is an earthquake.

[0012] The seismic sensor according to the fourth invention is a seismic sensor according to any one of the first to third inventions, further comprising a rotation period calculation unit that calculates the rotation period of rotation in the rotation direction determined by the rotation direction determination unit. This makes it possible to use the rotation period as a determination factor when determining whether the detected vibration is an earthquake or noise.

[0013] The fifth seismic sensor is the same as the fourth seismic sensor, further comprising a rotation period fluctuation determination unit that determines the variation in the rotation period calculated by the rotation period calculation unit. This makes it possible to determine whether the detected vibration is an earthquake or noise based on the result of determining the variation in the calculated rotation period.

[0014] The seismic sensor according to the sixth invention is the same as the seismic sensor according to the fifth invention, wherein the seismic determination unit increases the fluctuation count when the fluctuation of the rotation period of rotation in the rotation direction calculated by the rotation period calculation unit is smaller than a predetermined threshold, and determines that the vibration is noise when the count is greater than a predetermined number of times. As a result, by detecting rotation in which the number of times there was no fluctuation in the rotation period is greater than a predetermined threshold, it is possible to accurately determine that the detected vibration is noise.

[0015] The seismic sensor according to the seventh invention is the same as the seismic sensor according to the fifth invention, wherein the earthquake determination unit initializes the fluctuation count when the fluctuation of the rotation period of rotation in the rotation direction calculated by the rotation period calculation unit is greater than a predetermined threshold, and determines that the vibration is an earthquake when the count is less than a predetermined number of times. In this way, in order to detect earthquakes including various rotation periods, it is possible to accurately determine that the detected vibration is an earthquake by detecting rotations in which the number of times there was no fluctuation in the rotation period is less than a predetermined threshold.

[0016] The earthquake sensor according to the eighth invention is an earthquake sensor according to any one of the first to third inventions, further comprising an earthquake magnitude calculation unit that determines whether or not 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.

[0017] The seismic sensor according to the ninth invention is a seismic sensor according to any one of the first to third inventions, 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.

[0018] The earthquake sensor according to the tenth invention is an earthquake sensor according to any one of the first to third inventions, 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, for example, when an earthquake occurs, the output unit to output a shutoff signal to stop the supply of energy such as electricity and gas, or a warning signal to indicate danger.

[0019] The seismic sensor according to the eleventh invention is a seismic sensor according to any one of the first to third inventions, further comprising a storage unit for storing the judgment results from the rotation direction determination unit and the earthquake determination unit. This allows necessary information to be retrieved from the storage unit that stores each judgment result, and for displaying or notifying earthquake judgment results, etc.

[0020] The earthquake determination method according to the twelfth invention acquires the acceleration of vibration, determines the direction of rotation from the direction of movement of the acceleration in a coordinate plane along the horizontal plane of the acquired acceleration, and determines whether or not the vibration is an earthquake according to the rotation in the determined direction of rotation.Here, for example, in order to avoid misidentifying a seismic sensor installed at the tip of a rod-shaped member as an earthquake when it is rotating due to vibrations other than an earthquake, the method determines whether or not the detected vibration is an earthquake according to the presence or absence of a predetermined rotation.

[0021] In this earthquake detection method, the seismic sensor is installed, for example, on an energy measuring instrument such as a gas or electricity meter, and is set up to shut off the energy supply when an earthquake of a predetermined seismic intensity or higher is detected. In the acceleration acquisition step, the acceleration of the vibration applied to the seismic sensor may be measured directly, or the measured acceleration may be acquired.

[0022] Here, if the presence or absence of rotation is determined from the acceleration of the vibration, for example, if the rotation is above a predetermined number of rotations, or if the number of times there was no fluctuation (variation) in the rotation period is greater than a predetermined threshold, it is estimated to be a vibration exhibiting noise characteristics. Conversely, if the presence or absence of rotation is determined from the acceleration of the vibration, for example, if the rotation is below a predetermined number of rotations, or if the number of times there was no fluctuation (variation) in the rotation period is less than a predetermined threshold, it is estimated to be a vibration exhibiting earthquake characteristics.

[0023] This prevents the misidentification of vibrations containing a predetermined rotation as earthquakes, based on the determination of whether rotation is present or not from the acceleration of the detected vibrations. As a result, it is possible to accurately determine whether the detected vibration is an earthquake or noise.

[0024] The earthquake determination program according to the 13th invention acquires the acceleration of vibration, determines the direction of rotation from the direction of movement of the acceleration in a coordinate plane along the horizontal plane of the acquired acceleration, and causes the computer to execute an earthquake determination method that determines whether or not the vibration is an earthquake according to the rotation in the determined direction of rotation.

[0025] Here, to avoid misidentifying a vibration as an earthquake, for example, when a seismic sensor installed at the tip of a rod-shaped member rotates due to vibrations other than an earthquake, the system determines whether the detected vibration is an earthquake based on whether or not it rotates as specified. In this case, the seismic sensor that runs this earthquake determination program is installed, for example, on energy measuring instruments such as gas or electricity, and is installed to shut off the energy supply if an earthquake of a certain seismic intensity or higher is detected.

[0026] In the acceleration acquisition step, the acceleration of the vibration applied to the seismic sensor may be measured directly, or the measured acceleration may be acquired. Here, if the presence or absence of rotation is determined from the acceleration of the vibration, for example, if the rotation is above a predetermined number of rotations, or if the number of times there was no fluctuation (variation) in the rotation period is greater than a predetermined threshold, it is estimated that the vibration exhibits noise characteristics.

[0027] Conversely, if the presence or absence of rotation is determined from the acceleration of the vibration, for example, if the rotation is below a predetermined number of rotations, or if the number of times there was no fluctuation (variation) in the rotation period is below a predetermined threshold, it is estimated that the vibration exhibits characteristics of an earthquake. This prevents misidentification of vibrations containing a predetermined rotation as an earthquake based solely on the determination of the presence or absence of rotation from the detected vibration acceleration. As a result, it is possible to accurately determine whether the detected vibration is an earthquake or noise.

[0028] (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.

[0029] 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 graph showing the acceleration distribution on the horizontal plane (XY plane) of vibrations due to noise detected by the earthquake sensor in Figure 2. (a) to (d) are diagrams explaining the process of determining the presence or absence of rotation from the quadrant shift of acceleration. A flowchart showing the processing flow of the earthquake determination method executed by the earthquake sensor in Figure 2.

[0030] An earthquake sensor 10 and earthquake determination method according to one embodiment of the present invention will be described below with reference to Figures 1 to 5. 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 redundant and to facilitate understanding by those skilled in the art.

[0031] Furthermore, the applicant provides the accompanying drawings and the following description so that those skilled in the art may fully understand the present invention, and not intends to limit the subject matter described in the claims.

[0032] (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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] (2) Functional Blocks of the Seismic Sensor 10 As shown in Figure 2, the seismic sensor 10 includes an acceleration acquisition unit 21, a vibration intensity classification / startup determination unit 22, a quadrant determination unit 23, a rotation direction determination unit 24, a rotation period calculation unit 25a, a rotation count / period fluctuation 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 storage unit 30.

[0038] These functional blocks shown in FIG. 2 are configured such that the controller 12 receives acceleration data acquired from the acceleration sensor 11 and reads a program stored in the memory 13. The acceleration acquisition unit 21 acquires measurement data of acceleration measured by the acceleration sensor 11 at a predetermined period. Note that the acceleration acquisition unit 21 usually acquires measurement data of acceleration measured repeatedly at a relatively low speed (i.e., a relatively long measurement period).

[0039] 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, since the acceleration sensor 11 is in an operation state of performing sampling at a low speed, the controller 12 suppresses power consumption by operating in a sleep mode with limited functions.

[0040] Further, when the acceleration acquisition unit 21 acquires vibrations greater than a threshold value preset in the storage unit 30, the acceleration sensor 11 repeats acceleration measurement at a higher speed (i.e., a relatively short period) than during low-speed sampling. In such high-speed sampling, the controller 12 operates in the sleep mode or the active mode. When the earthquake determination unit 26 or the like described later executes processing, the controller 12 operates in the active mode (measurement mode). Also, the transition from the power-saving mode to the measurement mode is called activation of the earthquake sensor 10.

[0041] Since the measurement mode is an operation state of performing high-speed sampling, the controller 12 may operate in a sleep mode with limited functions or may operate in an active mode with maximum computing power. In the measurement mode, the sampling period becomes shorter, and since the controller 12 is switched from the sleep mode to the active mode, the power consumption becomes larger than in the power-saving mode.

[0042] The vibration intensity classification / start determination unit 22 is a function on the acceleration sensor 11 side. It compares the value of the acceleration acquired by the acceleration acquisition unit 21 with the start threshold value held in the storage unit 30. When the value of the acceleration exceeds the start threshold value, it causes a transition from the power-saving mode to the measurement mode (activates the earthquake sensor 10). Also, the vibration intensity classification / start determination unit 22 calculates the intensity of the vibration from the measurement result in the acceleration acquisition unit 21. When the vibration intensity is greater than or equal to a predetermined magnitude, it causes a transition from the power-saving mode to the measurement mode, which has a higher power consumption than the power-saving mode (activates the controller 12).

[0043] Here, the vibration intensity classification process performed by the vibration intensity classification / start determination unit 22 is implemented by performing filtering processing on the value of the acceleration acquired by the acceleration acquisition unit 21. At this time, the filtered acceleration is stored in the storage unit 30. The quadrant determination unit 23 determines in which of the four quadrants formed in the coordinate plane (XY plane) (see FIG. 3) along the horizontal plane of the acceleration measured by the acceleration acquisition unit 21 the measured acceleration is located.

[0044] As shown in FIGS. 4(a) to 4(d), the four quadrants formed in the horizontal coordinate plane are four areas delimited by the x-axis and the y-axis, consisting of the first quadrant (x+ side, y+ side), the second quadrant (x− side, y+ side), the third quadrant (x− side, y− side), and the fourth quadrant (x+ side, y− side). The rotation direction determination unit 24 determines the rotation direction from the moving direction of the quadrant when the quadrant of the acceleration determined by the quadrant determination unit 23 moves.

[0045] The rotation period calculation unit 25a calculates the rotation period of the rotation in the rotation direction determined by the rotation direction determination unit 24. Note that the rotation period means the sum of the previous value and the current value of the time during which the acceleration determined by the quadrant determination unit 23 continues to be in the same quadrant. The rotation number / period fluctuation determination unit 25b determines the variation in the rotation period calculated by the rotation period calculation unit 25a.

[0046] The earthquake determination unit 26 determines whether the detected vibration is an earthquake or not, according to the rotation in the rotation direction determined by the rotation direction determination unit 24. In this embodiment, the seismic sensor 10 avoids misidentifying the detected vibration as an earthquake by detecting that the detected vibration has noise characteristics. Generally, the seismic sensor 10 is fixed to the tip of a rod-shaped member installed on the ground. In such an installation structure, if the detected vibration is noise, the vibration detected by the seismic sensor 10 tends to be a vibration that continues to rotate in the same direction on a horizontal plane, or a vibration that rotates in the same direction with a constant period.

[0047] On the other hand, if the detected vibration is an earthquake, the vibration detected by the seismic sensor 10 tends to be a vibration that rotates in various directions on the horizontal plane (not rotating in the same direction), or a vibration that rotates with various rotation periods (not with a nearly constant rotation period). Therefore, the seismic sensor 10 of this embodiment determines whether the detected vibration is an earthquake or noise based on the presence or absence of rotation detected by the movement of the vibration's acceleration in the four quadrants of the XY coordinates along the horizontal plane, which is acquired by the acceleration acquisition unit 21.

[0048] More specifically, the seismic sensor 10, in its rotation direction determination unit 24 and rotation period calculation unit 25a, determines the direction (clockwise or counterclockwise) in which the acceleration on the coordinate plane rotated from the start to the end of the vibration, and calculates the amount (number of rotations) and period of that rotation. The earthquake determination unit 26 uses the number of rotations in the same direction and / or the variation in the period of that rotation to determine whether it is an earthquake or noise.

[0049] The earthquake determination unit 26 determines that a vibration is noise if, for example, the number of consecutive rotations in the same direction is greater than a predetermined threshold (e.g., 10 rotations (quadrant 40)) or the rotation period fluctuation count is greater than a predetermined threshold (e.g., 5 rotations (quadrant 20)), and otherwise determines that the vibration is an earthquake. Specifically, as shown in Figure 4(a), if the acceleration measured to be in quadrant II moves to quadrant I, the rotation direction determination unit 24 determines that the vibration has rotated clockwise, and if it moves to quadrant III, it determines that the vibration has rotated counterclockwise.

[0050] In this embodiment, as shown in Figures 4(a) to 4(d), the seismic sensor 10 incorporates hysteresis to prevent the movement of acceleration quadrants across the X or Y axes near the X or Y axis from being detected as rotation. To achieve this, the area where the detected acceleration is located (grid-like area) is set to be wide enough to include the intersection of the X and Y axes.

[0051] Furthermore, the area containing the first quadrant (the area with a diagonal diagonal line to the lower right), which is rotated and moved from the grid-like area, is set to also include a part of the upper right area of ​​the fourth quadrant, and the area containing the third quadrant (the area with a diagonal diagonal line to the lower left), is set to also include a part of the lower left area of ​​the fourth quadrant. This makes it possible to determine whether the direction of rotation is clockwise or counterclockwise, even if the next detected acceleration moves, for example, from the second quadrant to the diagonally opposite fourth quadrant.

[0052] For example, if the acceleration in the second quadrant shown in Figure 4(a) moves clockwise to the first quadrant shown in Figure 4(b), the system detects again which quadrant the next detected acceleration will be in. If the next detected acceleration moves to the fourth quadrant, the rotation direction determination unit 24 determines that the clockwise rotation is continuing. On the other hand, if the next detected acceleration returns to the second quadrant, the rotation direction determination unit 24 determines that the clockwise rotation has stopped and has transitioned to counterclockwise rotation.

[0053] Next, if the acceleration in the first quadrant shown in Figure 4(b) moves clockwise to the fourth quadrant shown in Figure 4(d), the system detects again which quadrant the next detected acceleration will be in. Here, if the next detected acceleration moves to the third quadrant, the rotation direction determination unit 24 determines that the clockwise rotation is continuing. On the other hand, if the next detected acceleration returns to the first quadrant, the rotation direction determination unit 24 determines that the clockwise rotation has stopped and has transitioned to counterclockwise rotation.

[0054] Next, if the acceleration in the IV quadrant shown in Figure 4(d) moves clockwise to the III quadrant shown in Figure 4(c), the rotation direction determination unit 24 detects again which quadrant the next detected acceleration is in. Here, if the next detected acceleration moves to the II quadrant, the rotation direction determination unit 24 determines that the clockwise rotation is continuing. On the other hand, if the next detected acceleration returns to the IV quadrant, the rotation direction determination unit 24 determines that the clockwise rotation has stopped and has transitioned to counterclockwise rotation.

[0055] In other words, the rotation direction determination unit 24 detects whether or not there is rotation clockwise or counterclockwise by detecting the movement of the quadrant of the vibration acceleration as described above. Then, the rotation count / period fluctuation determination unit 25b determines the number of rotations in the rotation direction determined by the rotation direction determination unit 24 and the fluctuation of the rotation period calculated by the rotation period calculation unit 25a.

[0056] For example, if the rotation period calculation unit 25a detects a vibration that continues to rotate clockwise, with a dwell time of 10 seconds in the second quadrant, 7 seconds in the first quadrant, 8 seconds in the fourth quadrant, and 9 seconds in the third quadrant, the rotation period T is calculated as 10 + 7 = 17 seconds, 7 + 8 = 15 seconds, and 8 + 11 = 19 seconds. In this case, the rotation period T from the second quadrant to the first quadrant is calculated as follows: １ = 17 seconds, rotation period T from quadrant I to quadrant IV ２ = 15 seconds, rotation period T from the IVth quadrant to the IIIrd quadrant. ３ = 19 seconds.

[0057] Then, based on the period calculated by the rotation period calculation unit 25a, the rotation speed and periodic fluctuation determination unit 25b determines whether, for example, the following relational expression (1) is satisfied. |T (n+1) −T n |<max{(T_(n + 1), T_n)}×0.15 ・・・・(1) Here, when the relational expression (1) is satisfied, it is determined that the period variation is small, and the rotation period fluctuation count is incremented (+1). On the other hand, when the relational expression (1) is not satisfied, it is determined that the period variation is large, and the rotation period fluctuation count is initialized to 0.

[0058] Note that for the above rotation period T (T １ = 17 seconds, T ２ = 15 seconds, T ３ = 19 seconds), |T2 - T1| = |15 - 17| = 2 max{T2, T1}×0.15 =17×0.15 = 2.55 (2 < 2.55). Therefore, in this case, since the relational expression (1) is satisfied, the count is incremented (+1).

[0059] On the other hand, |T ３ −T2| = |19 - 15| = 4 max{T3, T2}×0.15 =19×0.15 = 2.85 (4 > 2.85). Therefore, in this case, since the relational expression (1) is not satisfied, the count is initialized to 0.

[0060] When the rotation period fluctuation count in the rotation direction determined by the rotation direction determination unit 24 is greater than a predetermined threshold, the earthquake determination unit 26 determines that the vibration is noise. On the other hand, when the rotation period fluctuation count in the rotation direction determined by the rotation direction determination unit 24 is less than or equal to a predetermined threshold, the earthquake determination unit 26 determines that the vibration is an earthquake. Further, when the number of times there is no fluctuation in the rotation period of the rotation in the rotation direction calculated by the rotation period calculation unit 25a is greater than a predetermined threshold, the earthquake determination unit 26 determines that the vibration is noise. On the other hand, when the number of times there is no fluctuation in the rotation period of the rotation in the rotation direction calculated by the rotation period calculation unit 25a is less than or equal to a predetermined threshold, the earthquake determination unit 26 determines that the vibration is an earthquake.

[0061] The earthquake magnitude calculation unit 27 determines whether the earthquake is of a predetermined seismic intensity or higher when the earthquake determination unit 26 determines that an earthquake has occurred. Furthermore, if 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, and then detects vibrations that can be considered noise such as shocks, it excludes those vibrations and calculates the magnitude of the earthquake.

[0062] 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.

[0063] The memory unit 30 stores, for example, acceleration data acquired by the acceleration acquisition unit 21, the determination results from the quadrant determination unit 23, the rotation direction determination unit 24, the rotation count / period fluctuation determination unit 25b, and the earthquake determination unit 26.

[0064] <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 5.

[0065] 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 quadrant determination unit 23 determines the current quadrant to which the detected acceleration belongs. Next, in step S13, the rotation direction determination unit 24 determines whether the previous quadrant is different from the current quadrant, that is, whether there has been a shift in the quadrant.

[0066] Here, if it is determined that the previous quadrant is different from the current quadrant (there has been a quadrant shift), the process proceeds to step S14. If it is determined that the previous quadrant is the same as the current quadrant (there has been no quadrant shift), the process returns to step S11 and repeats the transition. Next, in step S14, since it was determined in step S13 that the previous quadrant was different from the current quadrant (there has been a quadrant shift), the rotation direction determination unit 24 determines the rotation direction from the direction of the quadrant shift, and the rotation period calculation unit 25a calculates the period of that rotation.

[0067] Next, in step S15, it is determined whether the rotation direction determined by the rotation direction determination unit 24 in step S14 continues to be the same rotation direction. If it is determined that the same rotation direction continues, the process proceeds to step S16; if it is determined that the rotation direction is not the same (reverse rotation), the process proceeds to step S20. Next, in step S16, the rotation count / period fluctuation determination unit 25b determines that the same rotation direction continued in step S15, and therefore sets the rotation direction count to +1.

[0068] Next, in step S17, the rotation direction / period fluctuation determination unit 25b determines whether the fluctuation (variation) of the rotation period calculated in step S14 exceeds a predetermined threshold. If it is determined that the fluctuation (variation) of the rotation period is less than the predetermined threshold, the process proceeds to step S18. If it is determined that the fluctuation (variation) of the rotation period is greater than or equal to the predetermined threshold, the process proceeds to step S19.

[0069] Next, in step S18, since it was determined in step S17 that the fluctuation (variation) of the rotation period is below a predetermined threshold, and the rotation period, which is a characteristic of noise, is almost constant, the rotation count / period fluctuation determination unit 25b sets the rotation period fluctuation count to +1 and proceeds to step S21. On the other hand, in step S19, since it was determined in step S17 that the fluctuation (variation) of the rotation period is above a predetermined threshold, and the rotation period, which is a characteristic of earthquakes, is variable, the rotation count / period fluctuation determination unit 25b initializes the rotation period fluctuation count to 0 and proceeds to step S21.

[0070] Furthermore, in step S20, since it was determined in step S15 that the rotation direction was not the same (reverse rotation), the rotation count / periodic fluctuation determination unit 25b initializes the rotation direction count to 0 and proceeds to step S21. Next, in step S21, the rotation count / periodic fluctuation determination unit 25b determines whether the vibration determination process has been completed.

[0071] If it is determined that the vibration detection process is complete, the process proceeds to the earthquake detection process in step S22. If it is determined that the vibration detection process is not complete, the process returns to step S11 and repeats. Next, in step S22, the earthquake detection unit 26 determines whether the rotation direction count is greater than a predetermined threshold for earthquake detection (for example, 10 rotations (40th quadrant)) or whether the rotation period fluctuation count is greater than a predetermined threshold for earthquake detection (for example, 5 rotations (20th quadrant)).

[0072] Here, if the rotation direction count is greater than a predetermined threshold for earthquake determination (e.g., 10 rotations (quadrant 40)), or if the rotation period fluctuation count is greater than a predetermined threshold for earthquake determination (e.g., 5 rotations (quadrant 20)), it is determined that the detected vibrations exhibit characteristics of noise including rotation rather than an earthquake, and the process proceeds to step S23. On the other hand, if the rotation direction count is less than or equal to the predetermined threshold for earthquake determination (e.g., 10 rotations (quadrant 40)), or if the rotation period fluctuation count is less than or equal to the predetermined threshold for earthquake determination (e.g., 5 rotations (quadrant 20)), it is determined that the detected vibrations exhibit characteristics of an earthquake, and the process proceeds to step S24.

[0073] Next, in step S23, the earthquake determination unit 26 determines, based on the result of the determination in step S22, that the detected vibration is noise and terminates the process. On the other hand, in step S24, the earthquake determination unit 26 determines, based on the result of the determination in step S22, that the detected vibration is an earthquake and terminates the process.

[0074] <Main Features> As shown in Figure 2, the seismic sensor 10 of this embodiment includes an acceleration acquisition unit 21, a quadrant determination unit 23, a rotation direction determination unit 24, and an earthquake determination unit 26. The acceleration acquisition unit 21 detects vibration and acquires the acceleration of the vibration. The quadrant determination unit 23 determines the quadrant formed on the coordinate plane along the horizontal plane of the acceleration measured by the acceleration acquisition unit 21. The rotation direction determination unit 24 determines the rotation direction from the movement of the quadrant of the acceleration determined by the quadrant determination unit 23. The earthquake determination unit 26 determines whether the vibration is an earthquake or not according to the rotation in the rotation direction determined by the rotation direction determination unit 24.

[0075] This allows for earthquake detection by determining whether the detected vibration is an earthquake or noise based on the results of determining whether rotation is present from the acceleration waveform of the detected vibration. By combining various feature points that appear in the acceleration waveform of an earthquake, it is possible to accurately determine whether the detected vibration is an earthquake or noise.

[0076] [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. (A) In the above embodiment, the present invention was described using an example 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 realized as an earthquake determination program that causes a computer to execute the earthquake determination method using the seismic sensor described above.

[0077] 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.

[0078] (B) In the above embodiment, an example was given in which the seismic determination unit 26 determines that the detected vibration is noise when the rotation continues to exceed a predetermined threshold, or when the number of times there was no periodic fluctuation of rotation is greater than a predetermined threshold. However, the present invention is not limited thereto.

[0079] For example, the earthquake detection unit may be configured to perform earthquake / noise determination by detecting only one of the following: that rotation continues at or above a predetermined threshold, or that the number of times there is no rotational periodic fluctuation is greater than a predetermined threshold. Alternatively, the earthquake detection unit may be configured to perform earthquake / noise determination using rotational parameters other than the number of rotations and rotational periodic fluctuations.

[0080] (C) In the above embodiment, an example was given in which the threshold for the number of rotations was set to 10 rotations (40 quadrants) and the threshold for the number of rotations without fluctuation in the rotation period was set to 5 rotations (20 quadrants) as thresholds for earthquake determination. However, the present invention is not limited thereto. For example, the value of the threshold for earthquake determination can be appropriately changed depending on the environment, structure, etc., in which the seismic sensor is installed.

[0081] (D) In ​​the above embodiment, an example was given in which the seismic sensor 10 is attached to the tip of a rod-shaped member. However, the present invention is not limited thereto. For example, the seismic sensor may be installed on a base other than a rod.

[0082] (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.

[0083] <Note> The seismic sensor according to the first invention comprises: an acceleration acquisition unit that acquires the acceleration of vibration; a rotation direction determination unit that determines the rotation direction from the direction of movement of the acceleration in a coordinate plane along the horizontal plane of the acceleration acquired by the acceleration acquisition unit; and an earthquake determination unit that determines whether or not the vibration is an earthquake according to the rotation in the rotation direction determined by the rotation direction determination unit.

[0084] The seismic sensor according to the second invention is the seismic sensor according to the first invention, wherein the earthquake determination unit determines that the vibration is noise if the continuous rotation in the rotation direction determined by the rotation direction determination unit is equal to or greater than a predetermined number of rotations. 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 vibration is an earthquake if the continuous rotation in the rotation direction determined by the rotation direction determination unit is less than the predetermined number of rotations.

[0085] The seismic sensor according to the fourth invention is a seismic sensor according to any one of the first to third inventions, further comprising a rotation period calculation unit that calculates the rotation period of rotation in the rotation direction determined by the rotation direction determination unit. The seismic sensor according to the fifth invention is a seismic sensor according to the fourth invention, further comprising a rotation period fluctuation determination unit that determines the variation of the rotation period calculated by the rotation period calculation unit.

[0086] The seismic sensor according to the sixth invention is the seismic sensor according to the fifth invention, wherein the earthquake determination unit increases the count of the fluctuations when the fluctuation of the rotation period of the rotation in the rotation direction calculated by the rotation period calculation unit is smaller than a predetermined threshold, and determines that the vibration is noise when the count is greater than a predetermined number of times. The seismic sensor according to the seventh invention is the seismic sensor according to the fifth invention, wherein the earthquake determination unit initializes the count of the fluctuations when the fluctuation of the rotation period of the rotation in the rotation direction calculated by the rotation period calculation unit is larger than a predetermined threshold, and determines that the vibration is an earthquake when the count is less than a predetermined number of times.

[0087] 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 earthquake magnitude calculation unit that determines whether or not an earthquake is of a predetermined seismic intensity or greater when an earthquake is determined to be occurring in the earthquake determination unit. 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 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.

[0088] The earthquake sensor according to the tenth invention is an earthquake sensor according to any one of the first to ninth inventions, further comprising an output control unit that outputs a predetermined signal when the earthquake determination unit determines that an earthquake has occurred. The earthquake sensor according to the eleventh invention is an earthquake sensor according to any one of the first to tenth inventions, further comprising a storage unit that stores the determination results in the rotation direction determination unit and the earthquake determination unit.

[0089] 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.

[0090] 10 Earthquake sensor 11 Acceleration sensor 12 Controller 13 Memory 14 Output unit 21 Acceleration acquisition unit 22 Vibration intensity classification / startup determination unit 23 Quadrant determination unit 24 Rotation direction determination unit 25a Rotation period calculation unit 25b Rotation count / period fluctuation determination unit 26 Earthquake determination unit 27 Earthquake magnitude calculation unit 28 Output control unit 30 Memory unit T Period

Claims

1. An earthquake sensor comprising: an acceleration acquisition unit that acquires the acceleration of vibration; a rotation direction determination unit that determines the rotation direction from the direction of movement of the acceleration in a coordinate plane along the horizontal plane of the acceleration acquired by the acceleration acquisition unit; and an earthquake determination unit that determines whether or not the vibration is an earthquake according to the rotation in the rotation direction determined by the rotation direction determination unit.

2. The seismic sensor according to claim 1, wherein the seismic determination unit determines that the vibration is noise when the continuous rotation in the rotation direction determined by the rotation direction determination unit is equal to or greater than a predetermined number of rotations.

3. The earthquake detection unit determines that the vibration is an earthquake when the continuous rotation in the rotation direction determined by the rotation direction detection unit is less than a predetermined number of rotations.

4. The seismic sensor according to any one of claims 1 to 3, further comprising a rotation period calculation unit for calculating the rotation period of rotation in the rotation direction determined by the rotation direction determination unit.

5. The seismic sensor according to claim 4, further comprising a rotation period fluctuation determination unit for determining the variation in the rotation period calculated by the rotation period calculation unit.

6. The seismic sensor according to claim 5, wherein the seismic determination unit increases the count of fluctuations when the fluctuation of the rotation period of rotation in the rotation direction calculated by the rotation period calculation unit is less than a predetermined threshold, and determines that the vibration is noise when the count is greater than a predetermined number of times.

7. The earthquake detection unit initializes the count of fluctuations if the fluctuation of the rotation period of the rotation in the rotation direction calculated by the rotation period calculation unit is greater than a predetermined threshold, and determines that the vibration is an earthquake if the count is less than a predetermined number of times, according to claim 5.

8. The seismic sensor according to any one of claims 1 to 3, 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.

9. The seismic sensor according to any one of claims 1 to 3, 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 which consumes more power than the power-saving mode if the intensity of the vibration is greater than or equal to a predetermined magnitude.

10. The earthquake sensor according to any one of claims 1 to 3, further comprising an output control unit that outputs a predetermined signal when the earthquake determination unit determines that an earthquake has occurred.

11. The seismic sensor according to any one of claims 1 to 3, further comprising a storage unit for storing the determination results in the rotation direction determination unit and the earthquake determination unit.

12. An earthquake determination method comprising: obtaining the acceleration of vibration; determining the rotational direction from the direction of movement of the acceleration in a coordinate plane along the horizontal plane of the obtained acceleration; and determining whether the vibration is an earthquake or not according to the rotation in the determined rotational direction.

13. An earthquake determination program that causes a computer to execute an earthquake determination method comprising: an acceleration acquisition step of acquiring the acceleration of vibration; and an acceleration acquisition step of acquiring the acceleration of vibration,

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