Earthquake sensor, earthquake detection method, and earthquake detection program

Abstract

This invention provides a seismic sensor, an earthquake detection method, and an earthquake detection program that can accurately determine whether detected vibrations are from an earthquake or noise. [Solution] The 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 the vibration. The rotation direction determination unit 24 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 21. 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.

Description

Technical Field

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

Background Art

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

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

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

[0005] 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. [Means for solving the problem]

[0006] 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, for example, to avoid misidentifying a vibration as an earthquake 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 or not based on whether or not it rotates as specified. In this context, the seismic sensor is installed, for example, in energy measuring instruments such as gas and electricity meters, to shut off the energy supply when it detects an earthquake of a predetermined magnitude or higher.

[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 presumed to be a vibration that exhibits characteristics of an earthquake. This prevents misidentification of vibrations that include a predetermined rotation as an earthquake, based on the determination of whether or not rotation is present from the detected vibration acceleration. As a result, it is possible to accurately determine whether the detected vibration is from 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 seismic determination unit determines that 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. This allows for the detection of continuous rotations exceeding a predetermined rotational speed, which do not appear in acceleration waveforms indicating earthquakes, thereby accurately determining that the detected vibrations are 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. This allows for accurate determination of whether the detected vibration is an earthquake by detecting continuous rotation below a predetermined rotation speed.

[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 allows the rotation period to be used as a determining factor when deciding whether the detected vibration is an earthquake or noise.

[0013] The seismic sensor according to the fifth invention is the seismic sensor according to the fourth invention, further comprising a rotation period fluctuation determination unit that determines the variation in the rotation period calculated by the rotation period calculation unit. This allows us to determine whether the detected vibration is an earthquake or noise based on the results 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 of the fluctuation 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. This allows for accurate determination that detected vibrations are noise by detecting rotations where the number of times there was no fluctuation in the rotation period exceeds a predetermined threshold.

[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 of the rotation period in the rotation direction calculated by the rotation period calculation unit if the fluctuation 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. This allows for the detection of earthquakes with various rotational periods by detecting rotations where the number of times there was no fluctuation in the rotational period is below a predetermined threshold, thereby accurately determining that the detected vibrations are earthquakes.

[0016] The seismic sensor according to the eighth invention is a seismic sensor according to any one of the first to third inventions, further comprising a seismic magnitude calculation unit that determines whether or not an earthquake is of a predetermined seismic intensity or higher when an earthquake is determined to be occurring in the earthquake determination unit. This allows for improved user safety, for example, by outputting a shutoff signal to stop energy supplies such as electricity and gas if an earthquake is determined to be of magnitude 5 or higher, potentially posing 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 which consumes more power than the power-saving mode if the intensity of vibration is greater than or equal to a predetermined magnitude. Thus, when the intensity of the detected vibration is greater than or equal to a predetermined magnitude (for example, equivalent to seismic intensity 4), by switching to a measurement mode in which earthquake determination processing or the like using the acceleration waveform of the vibration is performed, it is possible to perform highly accurate earthquake determination while suppressing power consumption.

[0018] The seismic sensor according to the tenth invention is a seismic sensor according to any one of the first to third inventions, and further includes an output control unit that outputs a predetermined signal when it is determined that an earthquake has occurred in the earthquake determination unit. Thus, for example, at the time of an earthquake, it is possible to output from the output unit a cutoff signal for stopping the supply of energy such as electricity and gas, a warning signal for notifying danger, or the like.

[0019] The seismic sensor according to the eleventh invention is a seismic sensor according to any one of the first to third inventions, and further includes a storage unit that stores the determination results in the rotation direction determination unit and the earthquake determination unit. Thus, it is possible to extract necessary information from the storage unit that stores each determination result and display or notify the earthquake determination result or the like.

[0020] The earthquake determination method according to the twelfth invention acquires the acceleration of vibration, determines the rotation direction from the moving direction of the acceleration in the coordinate plane along the horizontal plane of the acquired acceleration, and determines whether the vibration is an earthquake according to the rotation in the determined rotation direction. Here, for example, in order to avoid misjudging this as an earthquake when the seismic sensor installed at the tip of a rod-shaped member is rotating due to vibration other than an earthquake, it is determined whether the detected vibration is an earthquake according to the presence or absence of a predetermined rotation.

[0021] Here, the seismic sensor that implements this earthquake determination method is installed, for example, in an energy measuring instrument such as a gas or electric energy meter, and is installed to stop the supply of energy when an earthquake with 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 that the vibration exhibits 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 below a predetermined threshold, it is presumed to be a vibration that exhibits characteristics of an earthquake.

[0023] This prevents misidentification of vibrations that include a predetermined rotation as an earthquake, based on the determination of whether or not rotation is present from the detected vibration acceleration. As a result, it is possible to accurately determine whether the detected vibration is from 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, for example, to avoid misidentifying a vibration as an earthquake 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 or not based on whether or not it rotates as specified. In this case, the seismic sensors that execute this earthquake detection program are installed, for example, on energy measuring instruments such as gas and electricity, and are set up to shut off the energy supply when an earthquake of a predetermined 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 presumed to be a vibration that exhibits characteristics of an earthquake. This prevents misidentification of vibrations that include a predetermined rotation as an earthquake, based on the determination of whether or not rotation is present from the detected vibration acceleration. As a result, it is possible to accurately determine whether the detected vibration is from an earthquake or noise. [Effects of the Invention]

[0028] According to the seismic sensor of the present invention, it is possible to accurately determine whether the detected vibration is from an earthquake or noise. [Brief explanation of the drawing]

[0029] [Figure 1] A control block diagram showing the configuration of an earthquake sensor according to one embodiment of the present invention. [Figure 2] A functional block diagram generated within the seismic sensor shown in Figure 1. [Figure 3] Figure 2 shows a graph illustrating the acceleration distribution on the horizontal plane (XY plane) of vibrations caused by noise detected by the seismic sensor. [Figure 4] (a) to (d) are diagrams illustrating the process of determining whether or not rotation is occurring based on quadrant changes in acceleration. [Figure 5] A flowchart showing the processing flow of the earthquake detection method performed by the seismic sensor in Figure 2. [Modes for carrying out the invention]

[0030] An earthquake sensor 10 and earthquake detection method according to one embodiment of the present invention will be explained below with reference to Figures 1 to 5. In this embodiment, unnecessary details may be omitted. For example, detailed explanations of already well-known matters or redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding for 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 As shown in Figure 1, the seismic sensor 10 according to this embodiment includes an acceleration sensor 11, a controller 12, a memory 13, and an output unit 14. 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 acceleration measured by the acceleration sensor 11 at a predetermined period, and determines the occurrence of an earthquake and calculates an index value indicating the magnitude of the earthquake based on the acquired acceleration.

[0033] Furthermore, the controller 12 operates in different modes, such as 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 still accepting interrupts, or stopping the supply of the clock. In this sleep mode, power consumption can be reduced compared to active mode.

[0034] Active mode is a mode that 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 within the seismic sensor 10 when it reads the earthquake judgment program stored in memory 13 will be described in detail later. 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, acceleration measured by the acceleration sensor 11 and thresholds used for earthquake detection.

[0035] The memory 13 may also be the 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. 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. Furthermore, when an earthquake of a predetermined magnitude or greater is detected, the output unit 14 outputs a shut-off signal to external devices to stop the supply of energy such as electricity or gas.

[0036] (2) Functional block of 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.

[0037] These functional blocks shown in Figure 2 are configured by the controller 12 receiving acceleration data acquired from the acceleration sensor 11 and reading the program stored in the memory 13. The acceleration acquisition unit 21 acquires acceleration measurement data measured at a predetermined period by the acceleration sensor 11. Typically, the acceleration acquisition unit 21 acquires acceleration measurement data that is repeatedly measured at a relatively low speed (i.e., a relatively large measurement period).

[0038] When performing acceleration sampling at such low speeds, the controller 12 basically operates in a low-power sleep mode (standby state or power-saving mode). In the standby state, the acceleration sensor 11 is in an operating state that performs sampling at a low speed, so the controller 12 operates in a sleep mode with limited functionality, thereby suppressing power consumption.

[0039] Furthermore, when the acceleration acquisition unit 21 acquires vibrations greater than a threshold preset in the memory unit 30, the acceleration sensor 11 repeatedly measures acceleration at a higher speed (i.e., with a relatively smaller period) than during low-speed sampling. In such high-speed sampling, the controller 12 operates in sleep mode or active mode. Furthermore, when the earthquake detection unit 26, etc., described later, performs processing, the controller 12 operates in active mode (measurement mode). The transition from power-saving mode to measurement mode is called activating the seismic sensor 10.

[0040] The measurement mode is an operating state that performs high-speed sampling. Therefore, the controller 12 may operate in a sleep mode with limited functionality, or in an active mode that allows it to operate with maximum computing power. In measurement mode, the sampling period is shortened, and the controller 12 switches from sleep mode to active mode, resulting in higher power consumption than in power-saving mode.

[0041] The vibration intensity discrimination and activation determination unit 22 is a function of the acceleration sensor 11, and compares the acceleration value acquired by the acceleration acquisition unit 21 with the activation threshold held in the memory unit 30. If the acceleration value exceeds the activation threshold, it switches from power saving mode to measurement mode (activates the seismic sensor 10). Furthermore, the vibration intensity classification and activation determination unit 22 calculates the vibration intensity from the measurement results of the acceleration acquisition unit 21, and if the vibration intensity is greater than or equal to a predetermined magnitude, it switches from the power saving mode to the measurement mode, which consumes more power than the power saving mode (activates the controller 12).

[0042] Here, the vibration intensity classification process performed by the vibration intensity classification and activation determination unit 22 is carried out by filtering the acceleration values ​​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 which of the four quadrants formed on the coordinate plane (XY plane) (see Figure 3) along the horizontal plane of the acceleration measured by the acceleration acquisition unit 21 is in.

[0043] The four quadrants formed in the horizontal coordinate plane are four areas demarcated by the x-axis and y-axis, as shown in Figures 4(a) to 4(d), and consist 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 direction of movement of the quadrant if the quadrant of the acceleration determined by the quadrant determination unit 23 has moved.

[0044] The rotation period calculation unit 25a calculates the rotation period for the rotation direction determined by the rotation direction determination unit 24. The rotation period refers to the sum of the previous and current values ​​of the time that the acceleration determined by the quadrant determination unit 23 remains in the same quadrant. The rotation count / period fluctuation determination unit 25b determines the variation in the rotation period calculated by the rotation period calculation unit 25a.

[0045] 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 detects that the detected vibration has noise characteristics, thereby preventing the detected vibration from being mistakenly identified as an earthquake. 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 the horizontal plane, or a vibration that rotates in the same direction with a constant period.

[0046] 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 acceleration acquired by the acceleration acquisition unit 21 in the four quadrants of the XY coordinates along the horizontal plane.

[0047] 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 determines whether something is an earthquake or noise based on the number of rotations in the same direction and / or the variation in the period of those rotations.

[0048] The earthquake determination unit 26 determines the vibration as noise if, for example, the number of consecutive rotations in the same direction is greater than a predetermined threshold (e.g., 10 rotations (40th quadrant)), or if the rotational period fluctuation count is greater than a predetermined threshold (e.g., 5 rotations (20th quadrant)), and determines the vibration as an earthquake in all other cases. Specifically, as shown in Figure 4(a), if the acceleration measured in the second quadrant moves to the first quadrant, the rotation direction determination unit 24 determines that the vibration has rotated clockwise, and if it moves to the third quadrant, it determines that the vibration has rotated counterclockwise.

[0049] Furthermore, in the seismic sensor 10 of this embodiment, as shown in Figures 4(a) to 4(d), even when the quadrant of acceleration moves back and forth across the X or Y axis near the X or Y axis, 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, in order to provide hysteresis so as not to detect this as rotation.

[0050] Furthermore, the area containing Quadrant I, which is rotated and moved from the grid-like area (the area with diagonal lines to the lower right), is set to also include a part of the upper right area of ​​Quadrant IV, and the area containing Quadrant III, which is the area with diagonal lines to the lower left, is set to also include a part of the lower left area of ​​Quadrant IV. This allows us to determine whether the rotation direction is clockwise or counterclockwise, even if the next detected acceleration moves, for example, from the second quadrant to the diagonally opposite fourth quadrant.

[0051] 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 then detects which quadrant the next detected acceleration is 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.

[0052] 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 is in. 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.

[0053] Next, if the acceleration in the fourth quadrant shown in Figure 4(d) moves clockwise to the third quadrant shown in Figure 4(c), the system detects again which quadrant the next detected acceleration is in. Here, if the next detected acceleration moves to the second 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 fourth quadrant, the rotation direction determination unit 24 determines that the clockwise rotation has stopped and has transitioned to counterclockwise rotation.

[0054] 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. The rotation count / period fluctuation determination unit 25b then 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.

[0055] For example, if the rotation period calculation unit 25a detects an oscillation 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 T1 from the second quadrant to the first quadrant is 17 seconds, the rotation period T2 from the first quadrant to the fourth quadrant is 15 seconds, and the rotation period T3 from the fourth quadrant to the third quadrant is 19 seconds.

[0056] Then, the rotation count / period fluctuation determination unit 25b determines, for example, whether the following relational expression (1) is satisfied, based on the period calculated by the rotation period calculation unit 25a. |T (n+1) -T n | <max{(T_(n+1), T_n)}×0.15 ····(1) If relation (1) is satisfied, it is determined that the periodic variation is small, and the rotational periodic fluctuation count is incremented (+1). On the other hand, if relation (1) is not satisfied, it is determined that the periodic variation is large, and the rotational periodic fluctuation count is initialized to 0.

[0057] Furthermore, in the case of the above rotation period T (T1=17 seconds, T2=15 seconds, T3=19 seconds), |T2-T1|=|15-17|=2 max{T2, T1}×0.15=17×0.15=2.55 Therefore, (2 < 2.55). Thus, in this case, the relationship (1) is satisfied, so the count is incremented (+1).

[0058] on the other hand, |T3-T2|=|19-15|=4 max{T3, T2}×0.15=19×0.15=2.85 Therefore, (4 > 2.85). Thus, in this case, relation (1) is not satisfied, so the count is initialized to 0.

[0059] The earthquake determination unit 26 determines that the vibration is noise if the rotation period fluctuation count in the rotation direction determined by the rotation direction determination unit 24 is greater than a predetermined threshold. On the other hand, the earthquake determination unit 26 determines that the vibration is an earthquake if 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. Furthermore, the earthquake determination unit 26 determines that the vibration is noise if the number of times there was no fluctuation in the rotation period of the rotation in the direction of rotation, as calculated by the rotation period calculation unit 25a, is greater than a predetermined threshold. On the other hand, the earthquake determination unit 26 determines that the vibration is an earthquake if the number of times there was no fluctuation in the rotation period of the rotation in the direction of rotation, as calculated by the rotation period calculation unit 25a, is less than or equal to a predetermined threshold.

[0060] The earthquake magnitude calculation unit 27 determines whether or not an earthquake is of a predetermined seismic intensity or higher when the earthquake determination unit 26 determines that an earthquake has occurred. Furthermore, the earthquake magnitude calculation unit 27, after determining that the detected vibration is an earthquake and starting to calculate an index indicating the magnitude of the earthquake, excludes vibrations that can be considered noise such as shocks when calculating the earthquake magnitude.

[0061] The output control unit 28 controls the output of a signal from the output unit 14, which outputs a predetermined signal, according to 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 signals output from the output unit 14 include, 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.

[0062] 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.

[0063] <Earthquake determination method> The earthquake detection method using the seismic sensor 10 of this embodiment can be explained as follows using the flowchart shown in Figure 5. In other words, 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.

[0064] If it is determined that the previous quadrant is different from the current quadrant (i.e., 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 (i.e., 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 (i.e., there was a shift in the quadrant), 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.

[0065] 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 direction of rotation is continuing, the process proceeds to step S16. If it is determined that the direction of rotation 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, so it sets the rotation direction count to +1.

[0066] 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 a 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 a predetermined threshold, the process proceeds to step S19.

[0067] 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 increases the rotation period fluctuation count by +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 is variable, which is a characteristic of earthquakes, the rotation count / period fluctuation determination unit 25b initializes the rotation period fluctuation count to 0 and proceeds to step S21.

[0068] Furthermore, in step S20, since it was determined in step S15 that the rotation direction was not the same (reverse rotation), the rotation count / period fluctuation determination unit 25b initializes the rotation direction count to 0 and proceeds to step S21. Next, in step S21, the rotation count / period fluctuation determination unit 25b determines whether the vibration determination process has been completed.

[0069] 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 determination unit 26 determines whether the rotation direction count is greater than a predetermined threshold for earthquake determination (for example, 10 rotations (40th quadrant)) or whether the rotation period fluctuation count is greater than a predetermined threshold for earthquake determination (for example, 5 rotations (20th quadrant)).

[0070] If the rotation direction count is greater than a predetermined threshold for earthquake determination (e.g., 10 rotations (40th quadrant)), or if the rotation period fluctuation count is greater than a predetermined threshold for earthquake determination (e.g., 5 rotations (20th quadrant)), it is determined that the detected vibrations are not earthquakes but rather noise characteristics including rotation, and the process proceeds to step S23. On the other hand, if the rotation direction count is less than or equal to a predetermined threshold for earthquake determination (e.g., 10 rotations (40th quadrant)), or if the rotation period fluctuation count is less than or equal to a predetermined threshold for earthquake determination (e.g., 5 rotations (20th quadrant)), it is determined that the detected vibrations exhibit characteristics of an earthquake, and the process proceeds to step S24.

[0071] Next, in step S23, the earthquake determination unit 26 determines, based on the determination result 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 determination result in step S22, that the detected vibration is an earthquake, and terminates the process.

[0072] <Key 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 a 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. 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, and by combining various feature points that appear in the acceleration waveform of an earthquake. As a result, it is possible to accurately determine whether the detected vibration is from an earthquake or noise.

[0073] [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 embodiments, examples of the present invention were described using the seismic sensor 10 and the earthquake determination method. However, the present invention is not limited thereto. For example, the present invention may be implemented as an earthquake determination program that causes a computer to execute the earthquake determination method using the seismic sensor described above.

[0074] This earthquake detection program is stored in the memory (storage unit) of the seismic sensor. The CPU reads the earthquake detection program stored in memory and has the hardware execute each step. More specifically, the same effect as described above can be obtained by having the CPU read the earthquake detection program and execute the steps described above. Furthermore, the present invention may be implemented as a recording medium that stores an earthquake judgment program for a seismic sensor.

[0075] (B) In the above embodiment, an example was given in which the earthquake determination unit 26 determines that the detected vibration is noise if the rotation continues to exceed a predetermined threshold, or if the number of times there was no periodic fluctuation in the rotation is greater than a predetermined threshold. However, the present invention is not limited thereto.

[0076] 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 was no periodic fluctuation in rotation is greater than a predetermined threshold. Furthermore, the earthquake detection unit may be configured to perform earthquake / noise detection using rotation-related parameters other than the number of rotations and the periodic fluctuations of the rotation.

[0077] (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 threshold value for earthquake detection can be changed as appropriate depending on the environment, structure, etc., in which the seismic sensor is installed.

[0078] (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.

[0079] (E) In the above embodiment, an example was described in which a memory unit 30 for storing earthquake judgment results, etc., is provided inside the seismic sensor 10. However, the present invention is not limited to this. For example, the memory unit that stores the results of earthquake assessments, etc., may be located on an external server such as a cloud server.

[0080] <Note> The earthquake sensor according to the first invention is An acceleration acquisition unit that acquires the acceleration of vibrations, A 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, An earthquake determination unit determines whether the vibration is an earthquake or not, in accordance with the rotation in the rotation direction determined by the rotation direction determination unit, It is equipped with.

[0081] The seismic sensor according to the second invention is the seismic sensor according to the first invention, 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 a seismic sensor according to the first or second invention, 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.

[0082] The seismic sensor according to the fourth invention is a seismic sensor according to any one of the first to third inventions, The system further includes a rotation period calculation unit that calculates the rotation period of the rotation in the rotation direction determined by the rotation direction determination unit. The seismic sensor according to the fifth invention is the seismic sensor according to the fourth invention, The system further includes a rotation period fluctuation determination unit that determines the variation in the rotation period calculated by the rotation period calculation unit.

[0083] The earthquake sensor according to the sixth invention is the earthquake sensor according to the fifth invention, The earthquake determination unit increases the count of the fluctuations in the rotation period of the rotation in the rotation direction calculated by the rotation period calculation unit if the fluctuation is smaller than a predetermined threshold, and determines that the vibration is noise if 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, The earthquake determination unit initializes the count of fluctuations if the fluctuation of the rotation period 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.

[0084] The seismic sensor according to the eighth invention is a seismic sensor according to any one of the first to seventh inventions, The system further includes an earthquake magnitude calculation unit that determines whether an earthquake is of a predetermined seismic intensity or higher when the earthquake determination unit determines that an earthquake has occurred. The seismic sensor according to the ninth invention is a seismic sensor according to any one of the first to eighth inventions, The system further includes a startup determination unit that calculates the intensity of the vibration from the measurement results in the acceleration acquisition unit, and switches from the power-saving mode to a measurement mode that consumes more power than the power-saving mode if the intensity of the vibration is greater than or equal to a predetermined magnitude.

[0085] The earthquake sensor according to the 10th invention is an earthquake sensor according to any one of the 1st to 9th inventions, The earthquake determination unit further includes an output control unit that outputs a predetermined signal when it is determined that an earthquake has occurred. The seismic sensor according to the 11th invention is a seismic sensor according to any one of the first to tenth inventions, The system further includes a storage unit for storing the determination results from the rotation direction determination unit and the earthquake determination unit. [Industrial applicability]

[0086] 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. [Explanation of Symbols]

[0087] 10. Earthquake Sensor 11. Accelerometer 12 controllers 13 memory 14 Output section 21 Acceleration acquisition section 22 Vibration intensity classification / startup determination section 23 Quadrant judgment part 24 Rotation direction determination unit 25a Rotation period calculation unit 25b Rotation count / period fluctuation determination unit 26 Earthquake Determination Department 27 Earthquake scale calculation department 28 Output control unit 30 Storage section T period

Claims

1. An acceleration acquisition unit that acquires the acceleration of vibrations, A 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, An earthquake determination unit determines whether the vibration is an earthquake or not, in accordance with the rotation in the rotation direction determined by the rotation direction determination unit, An earthquake sensor equipped with this feature.

2. 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 claim 1.

3. 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 a predetermined number of rotations. The seismic sensor according to claim 1.

4. The system further includes a rotation period calculation unit that calculates the rotation period of the rotation in the rotation direction determined by the rotation direction determination unit. An earthquake sensor according to any one of claims 1 to 3.

5. The system further includes a rotation period fluctuation determination unit that determines the variation in the rotation period calculated by the rotation period calculation unit. The seismic sensor according to claim 4.

6. The earthquake determination unit increases the count of the fluctuations if the fluctuations in the rotation period of the rotation in the rotation direction calculated by the rotation period calculation unit are less than a predetermined threshold, and determines that the vibrations are noise if the counts are greater than a predetermined number of times. The seismic sensor according to claim 5.

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

8. The system further includes an earthquake magnitude calculation unit that determines whether an earthquake is of a predetermined seismic intensity or higher when the earthquake determination unit determines that an earthquake has occurred. An earthquake sensor according to any one of claims 1 to 3.

9. The system further includes a startup determination unit that calculates the vibration intensity from the measurement results of the acceleration acquisition unit, and, if the vibration intensity is greater than or equal to a predetermined magnitude, switches from the power-saving mode to a measurement mode that consumes more power than the power-saving mode. An earthquake sensor according to any one of claims 1 to 3.

10. The earthquake determination unit further includes an output control unit that outputs a predetermined signal when it is determined that an earthquake has occurred. An earthquake sensor according to any one of claims 1 to 3.

11. The system further includes a storage unit for storing the determination results from the rotation direction determination unit and the earthquake determination unit. An earthquake sensor according to any one of claims 1 to 3.

12. Obtain the acceleration of the vibration, In a coordinate plane along the horizontal plane of the acquired acceleration, the rotational direction is determined from the direction of movement of the acceleration. Depending on the rotation in the determined direction of rotation, it is determined whether the vibration is an earthquake or not. Earthquake determination method.

13. An acceleration acquisition step to obtain the acceleration of vibration, In a coordinate plane along the horizontal plane of the acquired acceleration, the rotational direction is determined from the direction of movement of the acceleration. Depending on the rotation in the determined direction of rotation, it is determined whether the vibration is an earthquake or not. An earthquake prediction program that uses a computer to execute earthquake prediction methods.

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