JP2011047657A - Seismic intensity measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To design a filter with low power consumption according to the meteorological agency definition, without complication of a circuit configuration. <P>SOLUTION: The filter 14 is provided with an extended filter 141, a recursive filter 142, an IIR filter 143, and an IIR filter 144. Each of the filters 141 to 144 is formed by the combination of an adding circuit, a subtracting circuit, and a shift arithmetic circuit. Seismic intensity is calculated based on acceleration waveform data output from the filter 14. In the calculation process of the seismic intensity, a calculated value is represented by two's power, and a simple calculation is carried out by using digit number of the maximum bit number. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an apparatus for measuring seismic intensity based on measured values of an acceleration sensor. The present invention also relates to an apparatus for shutting off gas when an earthquake occurs based on seismic intensity measurement results.

  The Japan Meteorological Agency defines the characteristics of filters for measuring seismic intensity. For measuring the seismic intensity, acceleration waveform data measured by an acceleration sensor is used. In order to measure accurate seismic intensity, it is necessary to apply a JMA-defined filter to acceleration waveform data.

  One way to apply the JMA-defined filter is as follows. An FFT operation is applied to acceleration waveform data on the time axis measured by the acceleration sensor. The acceleration waveform data on the frequency axis after the FFT calculation is corrected, and the characteristics defined by the Japan Meteorological Agency are applied. Acceleration waveform data that can be used for seismic intensity measurement is obtained by performing inverse FFT operation on the corrected data.

  In Patent Document 1, an attempt is made to design a filter defined by the Japan Meteorological Agency as a digital filter circuit. In Patent Document 2, an attempt is made to realize a filter defined by the Japan Meteorological Agency with an analog filter circuit.

The X, Y, Z, and three component acceleration waveform data are represented by A _X (t), A _Y (t), and A _Z (t). The acceleration waveform data obtained by applying the filter processing defined by the Japan Meteorological Agency to the acceleration waveform data A _X (t), A _Y (t), and A _Z (t) is expressed as H _X (t), H _Y (t). , H _Z (t). The sum of squares W ² (t) of the amplitude of the corrected acceleration waveform data is expressed as Equation 1.

The absolute value W (t) of the amplitude of the three components varies from moment to moment as the acceleration waveform data changes. When W (t) is 0.3 seconds or more and W _a or more, using the maximum value W _m of W _a , the measured seismic intensity S _m defined by the Japan Meteorological Agency is expressed as Equation 2 The In Equation 2, the coefficient C is the sensitivity of the acceleration sensor, and the coefficient A is the gain of the filter.

Thus, it is necessary to obtain the maximum value W _m of W _a for estimating the measured seismic intensity S _m , and various methods have been proposed.

In Patent Document 3, in order to obtain the maximum value W _m, we are prepared 30 memory. Thirty seismic intensities W (t) obtained by 100 Hz sampling are stored in the memory. When a new seismic intensity W (t) is added over time, the minimum value of the 30 seismic intensity W (t) stored in the memory is compared with the newly added seismic intensity W (t). If the new data is larger than the minimum value, the minimum value of the seismic intensity W (t) stored in the memory is deleted, and the new data is stored in the memory. Then, the minimum value of the seismic intensity W (t) stored in the memory is updated. In this way, the seismic intensity lasting 0.3 seconds or more is measured.

In Patent Document 1, the instantaneous value S (t) of the measured seismic intensity calculated when W (t) is substituted into Equation 2 is expressed as a discrete value. A memory location corresponding to each discrete value of the instantaneous value S (t) of the measured seismic intensity is prepared. Each memory location stores the appearance count number of each discrete value. Each time the instantaneous value S (t) of the measured seismic intensity is obtained, a discrete value of the instantaneous value S (t) of the measured seismic intensity is calculated, and the count value is added to the corresponding storage location. By analyzing the count value of the discrete values stored in each storage location, the measured seismic intensity S _{m in} which the instantaneous value S (t) continues for 0.3 seconds or more can be acquired.

JP 2008-107334 A JP 2000-346701 A JP 2007-198812 A

  As described above, Patent Document 1 or Patent Document 2 attempts to realize a filter defined by the Japan Meteorological Agency using a digital filter circuit or an analog filter circuit. However, there is a problem that the circuit is complicated and the power consumption is large.

  When the seismic intensity measuring device is battery driven, it is necessary to reduce power consumption. When an earthquake occurs, the situation where the battery capacity is reduced and the seismic intensity cannot be determined must be avoided.

  In view of the above problems, an object of the present invention is to provide a technique for realizing a JMA-defined filter with low power consumption and a technique for measuring seismic intensity with low power consumption.

  In order to solve the above-described problem, the seismic intensity measurement device according to claim 1 includes an acceleration input unit that inputs acceleration waveform data, a filter that performs filtering on the acceleration waveform data and outputs corrected acceleration waveform data, and the correction A seismic intensity calculator that calculates seismic intensity from acceleration waveform data, and the filter converts the acceleration waveform data into the corrected acceleration waveform data by combining an addition circuit, a subtraction circuit, and a bit shift operation circuit. Features.

  The seismic intensity measurement device according to claim 2, wherein an acceleration input unit that inputs acceleration waveform data, a filter that filters the acceleration waveform data and outputs corrected acceleration waveform data, and calculates a seismic intensity from the corrected acceleration waveform data A seismic intensity calculating unit that performs addition, subtraction, multiplication of powers of 2 and division of powers of 2 to perform the calculation by combining the acceleration waveform data with the corrected acceleration waveform data. It is characterized by converting into.

  According to a third aspect of the present invention, in the seismic intensity measurement device according to the first or second aspect, the filter includes a high-pass filter and a low-pass filter.

  According to a fourth aspect of the present invention, in the seismic intensity measurement device according to the third aspect, the high-pass filter has a differential filter, and the multiplication coefficient in the differential filter is a power of two.

  According to a fifth aspect of the present invention, in the seismic intensity measuring device according to the third aspect, the low-pass filter has a recursible filter, and the division coefficient in the recursible filter is a power of 2. To do.

  A sixth aspect of the present invention is the seismic intensity measuring apparatus according to the third aspect, wherein the low-pass filter has an IIR filter, and the division coefficient in the IIR filter is a power of two.

The seismic intensity measurement device according to claim 7, wherein an acceleration input unit that inputs acceleration waveform data, a filter that filters the acceleration waveform data and outputs corrected acceleration waveform data, and calculates an amplitude from the corrected acceleration waveform data An amplitude calculation unit configured to calculate the amplitude W (t) from the corrected acceleration waveform data, and to express the amplitude W (t) by a power of 2 , measured seismic intensity S (t) in terms of representing the, by the most significant number of bits in the case of representing the W (t) ⁶ in binary and B _N, the second seismic intensity measurements to determine the seismic intensity S (t) And a portion.

The invention of claim 8, wherein, in the seismic intensity measurement apparatus according to claim 7, further wherein the second seismic S measured by the seismic intensity measuring portion (t) is more than 0.3 seconds, in the case where the above S _a A maximum value determination unit that outputs the maximum value S _m of the values of S _a as the seismic intensity is provided.

  The invention according to claim 9 is the seismic intensity measuring device according to any one of claims 1 to 8, further comprising an A / D converter for A / D converting acceleration waveform data input to the acceleration input unit. And a sampling rate determining unit that determines a sampling rate of the A / D converter, wherein the sampling rate determining unit detects an earthquake with a different threshold according to the acceleration observed by the seismic intensity measurement device An occurrence detection unit; and a switching unit that switches a sampling rate of the A / D converter according to a detection result of the earthquake occurrence detection unit.

  According to a tenth aspect of the present invention, in the earthquake measurement device according to any one of the first to ninth aspects, when the duration of the seismic intensity calculated by the seismic intensity calculation unit is shorter than a predetermined time, It is characterized by canceling the measurement.

  The invention according to claim 11 is the earthquake measuring device according to any one of claims 1 to 10, further comprising a control for shutting off the gas when the seismic intensity calculated by the seismic intensity calculator exceeds a predetermined threshold. A gas cutoff control unit for performing the operation.

  According to the seismic measurement apparatus of the present invention, a filter that approximates characteristics and a filter defined by the Japan Meteorological Agency is configured by combining an addition circuit, a subtraction circuit, and a shift calculation circuit. A filter for seismic intensity measurement can be configured with low power consumption without complicating the circuit configuration.

  According to the seismic intensity measuring apparatus of the present invention, the calculated value is represented by a power of 2 and the seismic intensity is measured by a simple calculation using the number of digits of the maximum bit number of the calculated value. Seismic intensity measurement can be performed with low power consumption without complicating the circuit configuration.

It is a block diagram of a seismic intensity measuring device. It is a circuit block diagram of a filter. It is the figure which compared the filter defined by the Meteorological Agency definition and the filter approximated by this Embodiment. It is a circuit block diagram of a measurement seismic intensity calculation part. It is a figure which shows the experimental result of a seismic intensity measurement.

{1. Overall configuration of seismic intensity measuring device}
Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the overall configuration of the seismic intensity measurement system 1 will be described with reference to FIG.

  FIG. 1 is a block diagram of a seismic intensity measuring apparatus 1 according to the present embodiment. The seismic intensity measuring device 1 includes an acceleration sensor 11, an amplifier 12, an A / D converter 13, a filter 14, an amplitude calculating unit 15, a measured seismic intensity calculating unit 16, a seismic intensity determining unit 17, and a gas cutoff control unit 18. Yes. Further, the earthquake measurement device 1 includes an earthquake occurrence detection unit 19, a switching unit 20, and a battery 21.

  The earthquake measuring apparatus 1 of the present embodiment is installed near a gas flow valve, and controls the gas flow valve to shut off the gas when an earthquake occurs. The earthquake measuring device 1 includes a battery 21. The seismic measuring apparatus 1 normally operates by receiving power supply from a commercial power source. The earthquake measuring device 1 can be operated by driving the battery 21 when the power supply from the commercial power supply is interrupted during a disaster.

The acceleration sensor 11 can measure acceleration waveform data of three orthogonal components in the X, Y, and Z directions. The acceleration sensor 11 outputs three-component acceleration waveform data A _X (t), A _Y (t), and A _Z (t).

The acceleration waveform data A _X (t), A _Y (t), and A _Z (t) are amplified by the amplifier 12 and then A / D converted by the A / D converter 13. The sampling rate of the A / D converter 13 is switched based on switching control by the switching unit 20.

The acceleration waveform data A _X (t), A _Y (t), and A _Z (t) after A / D conversion are input to the filter 14. The filter 14 is a filter that is used approximately with respect to a filter defined by the Japan Meteorological Agency.

The acceleration waveform data A _X (t), A _Y (t), and A _Z (t) are subjected to filter processing in the filter 14 to obtain acceleration waveform data H _X (t), H _Y (t), H _Z Converted to (t). The acceleration waveform data H _X (t), H _Y (t), and H _Z (t) are input to the amplitude calculator 15.

The amplitude calculator 15 calculates the amplitude W (t) based on the acceleration waveform data H _X (t), H _Y (t), and H _Z (t). The amplitude W (t) is expressed as Equation 3.

  The amplitude W (t) calculated by the amplitude calculator 15 is input to the measured seismic intensity calculator 16. The measured seismic intensity calculation unit 16 calculates an instantaneous value S (t) of the measured seismic intensity from the amplitude W (t). The amplitude W (t) varies as the acceleration waveform data changes. Using the amplitude W (t), the instantaneous value S (t) of the measured seismic intensity defined by the Japan Meteorological Agency is expressed by the following equation (4). In Equation 4, the coefficient C is the sensitivity of the acceleration sensor, and the coefficient A is the gain of the filter.

  The measured seismic intensity calculation unit 16 calculates the measured seismic intensity S by analyzing the instantaneous value S (t) of the measured seismic intensity. The calculated measured seismic intensity S is input to the seismic intensity determination unit 17. The seismic intensity determination unit 17 determines whether the gas should be shut off based on the input measured seismic intensity S. When it is determined that the gas should be shut off, a control signal is output to the gas cutoff control unit 18. The gas cutoff control unit 18 performs gas cutoff control based on the control signal.

{2. Filter configuration}
Next, the configuration of the filter 14 will be described with reference to FIG. As shown in FIG. 2, the filter 14 includes a high-pass filter 141, a recursive filter 142, an IIR (Infinite Impulse Response) filter 143, and an IIR filter 144. The recursible filter 142 is a primary recursible filter. The IIR filter 143 and the IIR filter 144 are second-order IIR filters.

  The Japan Meteorological Agency-defined filter has a peak at about 0.5 Hz, and has a large attenuation in a frequency region higher than 10 Hz. In order to deal with such a JMA-defined filter, the filter 14 is created by combining a high-pass filter and a low-pass filter. A high-pass filter 141 is used as the high-pass filter. As the low-pass filter, a primary recursive filter 142 and secondary IIR filters 143 and 144 are used.

In the following description, the filter 14 performs a filter operation with X (t) as an input, and outputs F (t). Here, X (t) indicates acceleration waveform data A _X (t), A _Y (t), A _Z (t). That is, each process in the following description is actually an operation performed on each of the acceleration waveform data A _X (t), A _Y (t), and A _Z (t). Is a common process and will be described as an input X (t). In addition, the filter 14 receives acceleration waveform data A _X (t), A _Y (t), and A _Z (t), and the filter 14 performs acceleration waveform data H _X (t), H _Y (t), H _Z (t). ), Which are representatively described as output F (t).

  The high-pass filter 141 is a filter that calculates a differential value of the output of the acceleration sensor. The high-pass filter 141 is expressed by Equation 5 with X (t) as an input and Δt as a sampling interval.

A ₁ is a constant set in consideration of the digit loss caused by integer arithmetic. Exponent of A ₁ as 2 is set. Y ₁ (t) is the output of the high-pass filter 141.

Since A ₁ is a power number of 2, the last multiplication in number 5 expression may be included in a circuit with shift operation. The high-pass filter 141 is realized by one subtraction by the subtraction circuit and one shift operation by the shift operation circuit.

The output Y ₁ (t) of the high-pass filter 141 is input to the recursive filter 142 as a low-pass filter. The recursible filter 142 is a first-order recursible filter, and an operation represented by Equation 6 is performed on Y ₁ (t).

G ₁ is a coefficient that determines the characteristics of the recursive filter 142. The recursive filter 142 calculates a moving average value for G ₁ inputs. In general, this coefficient is a real number. In the present embodiment, as the coefficient G _1, exponent of 2 is used.

Since G ₁ is a exponent of 2, the last division in equation (6) may be a shift calculation circuit. The recursible filter 142 is realized by one addition by the adder circuit, one subtraction by the subtraction circuit, and one shift operation by the shift operation circuit.

As the low-pass filter, IIR filters 143 and 144 are used in addition to the recursive filter 142 of Formula 6. The output D ₂ (t) of the IIR filter 143 in the first stage is expressed by Equation 7 and Equation 8 with Y ₂ (t) as an input.

D ₁ (t) is a feedback term of the IIR filter 143. G ₂ and G ₃ are coefficients that determine the characteristics of the IIR filter 143. As the coefficient _G 2, _{G 3,} but in general real number used in the present embodiment, as the coefficient _G 2, _{G 3,} exponent of 2 is used.

Since G ₂ and G ₃ are powers of 2, the last division in Equation 7 and the last division in Equation 8 can be configured by a shift operation circuit. Further, multiplication of 2 in Formula 8 can also be configured by a shift operation circuit. The IIR filter 143 is realized by one addition by the addition circuit, one subtraction by the subtraction circuit, and one shift operation by the shift operation circuit with respect to the calculation of Expression 7. The IIR filter 143 is realized by performing one subtraction by the subtraction circuit, one addition by the addition circuit, and two shift operations by the shift operation circuit with respect to the calculation of Expression 8.

The output D ₂ (t) of the first stage IIR filter 143 is input to the second stage IIR filter 144. The second-stage IIR filter 144 receives D ₂ (t) as an input and performs calculations represented by Equation 9 and Equation 10.

D ₃ (t) is a feedback term of the IIR filter 144. G ₄ and G ₅ are coefficients that determine the characteristics of the IIR filter 144. As a coefficient _G 4, _{G 5,} although in general real number used in the present embodiment, as the coefficient _G 4, _{G 5,} exponent of 2 is used.

Since G ₄ and G ₅ are powers of 2, the last division in Equation 9 and the last division in Equation 10 can be configured by a shift operation circuit. Further, the multiplication of 2 in Formula 10 can also be configured by a shift operation circuit. The IIR filter 144 is realized by one addition by the addition circuit, one subtraction by the subtraction circuit, and one shift operation by the shift operation circuit with respect to the calculation of Equation (9). The IIR filter 144 is realized by performing one subtraction by the subtraction circuit, one addition by the addition circuit, and two shift operations by the shift operation circuit with respect to the calculation of Expression 10.

In order to set the gain of the output of the second-stage IIR filter 144 to 1.0, a coefficient A ₂ as shown in Equation 11 is required. In the high-pass filter 141 described above, and multiplied by a constant _{A 1.} The coefficient A ₂ is a coefficient for setting the gain of the filter 14 to 1.0 with respect to an arbitrary constant A ₁ .

Factor A ₂ is a real constant representing the gain of the filter. Since the coefficient A ₂ is a gain adjustment, there is no need to actually perform a division of the equation (11).

The factor A ₂ is a real number, but a real number for gain adjustment as described above, does not adversely affect the characteristics of the filter. That is, the filter 14 does not require a real number operation.

Using the filters 141 to 145 represented by the equations 5 to 11 described above and optimizing the coefficients A ₁ and A ₂ and the coefficients G _{1 to} G ₅ , the characteristics of the filter 14 can be changed to a JMA-defined filter. Approximate. Coefficients G _{1 to} G ₅ used in Expressions 5 to 11 are expressed by Expression 12. The subscript p in Expression 12 is an integer of 1 to 5.

In order to approximate the characteristics of the filter 14 of the present embodiment to a filter defined by the Japan Meteorological Agency, optimum G _{1 to} G ₅ are determined in advance. Specifically, k is changed from 0 to 9 for each G _p , and the filter characteristics are calculated for all 100,000 combinations in total. Among the 100,000 filter characteristics, the combination of k that is closest to the characteristics of the Japan Meteorological Agency-defined filter is determined. For example, the coefficient A ₂ is determined so that the gain of the filter is 1.0, and a combination of the coefficients G _p that minimizes the sum of squares of the difference between the characteristics of both filters is obtained.

  Conventionally, a filter whose coefficient is a real number is created using a combination of a recursible filter and a non-recursive filter. In the present embodiment, a filter that can express all coefficients as powers of 2 is designed by examining all 100,000 combinations.

By using the above method, unknown constants G ₁ to G ₅ are obtained. In FIG. 2, the output of the IIR filter 144 is D ₄ (t), but the calculation of Equation 11 is not executed in the filter 14. Therefore, the subsequent processing is executed here with D ₄ (t) = F (t).

In the present embodiment, the filter 14 is designed by setting each coefficient as follows.
A ₁ = 2 ⁴ = 16
G ₁ = 2 ⁴ = 16
G ₂ = 2 ⁴ = 16
G ₃ = 2 ¹ = 2
G ₄ = 2 ⁰ = 1
G ₅ = 2 ¹ = 2

  As described above, the filter 14 of the present embodiment realizes the seismic intensity filter defined by the Japan Meteorological Agency by approximate calculation using addition and subtraction of integers and a power of two. Since the filter 14 of the present embodiment does not use multiplication or division, the circuit configuration is simple and low power consumption can be achieved.

FIG. 3 compares the characteristics of the filter 14 actually designed by the above process with the characteristics of the filter defined by the Japan Meteorological Agency. In the figure, _{F 1} represents the characteristic of the filter 14, _{F 2} represents the JMA defined filters. It can be seen that the characteristics of both filters are very close.

As is apparent from the equations (3) to (11), the filter 14 is realized by an arithmetic operation of adding integers 5 times, subtracting 6 times, and bit shifting operation 9 times. In the present embodiment, as described above, since G ₄ = 2 ⁰ = 1 is set, this is realized by arithmetic operations of integer addition 5 times, subtraction 6 times, and bit shift operation 8 times. Therefore, the calculation time is reduced by about two orders of magnitude compared with the conventional calculation method using real numbers, and a significant reduction in power consumption is achieved. In addition, since a filter approximated to a filter defined by the Japan Meteorological Agency can be executed only by hardware without using a microcomputer, power consumption can be reduced.

{3. Calculation and determination of seismic intensity}
The above-described filter 14 converts the acceleration waveform data A _X (t), A _Y (t), A _Z (t) into acceleration waveform data H _X (t), H _Y (t), H _Z (t). Is done. Next, the amplitude W (t) is calculated based on the acceleration waveform data H _X (t), H _Y (t), and H _Z (t). Furthermore, the sensitivity C of the acceleration sensor 11, the gain of the filter 14 by using the coefficients A _2, which is set to 1.0 amplitude W (t) is corrected. Based on the corrected amplitude W (t), an instantaneous value S (t) of the measured seismic intensity is calculated, and finally the measured seismic intensity S is estimated.

<3-1. Theory of seismic intensity calculation>
First, the mathematical basis of the seismic intensity calculation in this embodiment will be described. In this embodiment, the measured seismic intensity is estimated with a resolution of 0.1. In order to express the instantaneous value S (t) of the measured seismic intensity expressed by Equation 4 using W (t) ⁶ , Equation 4 is transformed into Equation 13. W (t) ⁶ is obtained by raising Equation 3 to the third power.

In Equation 2, the measured seismic intensity S _m was calculated by inputting the amplitude W _m that continued for 0.3 seconds or more. On the other hand, in Equation 4, the instantaneous value S (t) of the measured seismic intensity is calculated by substituting W (t) that varies with time.

Next, W (t) ⁶ is replaced as shown in Equation 14.

  From the equation (13) and the equation (14), the instantaneous value S (t) of the measured seismic intensity can be transformed as the equation (15).

When the instantaneous value S (t) of the measured seismic intensity is calculated with a resolution of 0.1 from 4.0 or more, for example, it is handled as follows. When the instantaneous value S (t) of the measured seismic intensity is in the range from 3.95 to 4.05, 4.0 is associated as the instantaneous value S (t) of the measured seismic intensity. By substituting S (t) = 3.95 in equation (15), the number of digits A ₀ when the instantaneous value S (t) of the measured seismic intensity is 3.95 is given by equation (16) from equation (15). It is expressed as follows. In Equation 16 Equation, the coefficient C is the sensitivity of the acceleration sensor 11, the coefficient A ₂ is the gain of the filter is determined by the number 11 formula above.

Assuming that the number of digits of the maximum bit when B (t) ⁶ is expressed in binary is B ₄ (t), the instantaneous value S (t) of the measured seismic intensity is expressed by Equation 17 from Equations (15) to (16). It is expressed as an expression.

When calculating W (t) ⁶ , it is only necessary to use the digit of the maximum bit when expressed in binary. That is, it is not necessary to perform this calculation with high resolution, and it can be performed by changing to an integer calculation in consideration of digit loss.

According to the definition of seismic intensity of the Japan Meteorological Agency, the maximum value W _m of the value of W _a when W (t) is equal to or greater than W _a for 0.3 seconds or more is to be substituted into Equation 2. This definition is equivalent to obtaining the maximum value S _m of S _a when the instantaneous value S (t) of the measured seismic intensity is S _a or more for 0.3 seconds or more. Therefore, the maximum value S _m that is 0.3 seconds or longer can be obtained using Equation (17).

Here, a case where the measured seismic intensity is obtained with a resolution of 4.0 to 0.1 has been described as an example. The 4.0 term in Equation 17 represents the standard seismic intensity. For example, when the measured seismic intensity is obtained with a resolution of 5.0 to 0.1 (in this case, the reference seismic intensity is 5.0), the instantaneous value S (t) of the measured seismic intensity is 4.95 to 5.95. When the range is up to 05, 5.0 is associated as the instantaneous value S (t) of the measured seismic intensity. By substituting S (t) = 4.95 in Equation 4, the number of digits A ₀ when the instantaneous value S (t) of the measured seismic intensity is 4.95 is 3.95 in Equation 16. It may be replaced with 4.95. The instantaneous value S (t) of the measured seismic intensity may be replaced with 5.0 in Expression 17 below. More generally, in order to obtain seismic intensity N with a resolution of 0.1, in Equation 16, 3.95 can be replaced with (N-0.05), and 4.0 in Equation 17 can be replaced with N. That's fine.

<3-2. Configuration of seismic intensity calculation>
Next, a circuit configuration for calculating the amplitude W (t) and the instantaneous value S (t) of the measured seismic intensity and determining the measured seismic intensity S based on the mathematical basis described above will be described. FIG. 4 is a circuit block diagram of the amplitude calculator 15 and the measured seismic intensity calculator 16.

The amplitude calculator 15 receives the acceleration waveform data H _X (t), H _Y (t), and H _Z (t), and calculates the amplitude W (t) ² by performing the calculation shown in Equation 3. To do.

  The measured seismic intensity calculation unit 16 includes an approximate calculation unit 161, a digit number calculation unit 162, an instantaneous value calculation unit 163, and a maximum value determination unit 164.

The approximate calculation unit 161 outputs the number of digits M and K (t) ⁶ of the maximum bits of W (t) ² by performing the calculations shown in Formula 18 and Formula 19.

The number-of-digits calculation unit 162 calculates the number of digits A (the maximum number of bits of W (t) ⁶ from the number of digits M of the maximum bits of W (t) ^{2 and} the number of digits of the maximum bits of K (t) ^6. t).

When the instantaneous value calculation unit 163 inputs the number of digits A (t) of the maximum bits of W (t) ⁶ , the instantaneous value calculation unit 163 performs the calculation shown in Equation 20 and calculates the instantaneous value S (t) of the measured seismic intensity.

In Equation 20, A ₄ (t) = A (t) −A ₀ . A ₄ (t) calculated by the instantaneous value calculation unit 163 is input to the maximum value determination unit 164.

  When the instantaneous value S (t) of the measured seismic intensity is obtained with a resolution of 0.1, it is sufficient that A (t) is obtained as an integer from Equation 15. When the instantaneous value S (t) of the measured seismic intensity is obtained in the range from 4.0 to 7.0 in increments of 0.1, 31 counters are required. The counter 165 included in the maximum value determination unit 164 has 31 storage areas from first to 31st.

When A ₄ (t) input from the instantaneous value calculation unit 163 is 1 or more, 1 is added to the first to A ₄ (t) -th storage areas. When the input A ₄ (t) is 31 or more, 1 is added to all the storage areas.

Among the 31 pieces of the storage area, examining the storage area count is 30 or more, among the storage areas count becomes 30 or more, obtaining the number A ₄ of the storage area corresponding to the highest order bits. From number A ₄ in this storage area, measured seismic intensity S as shown in Equation 21 Equation is determined.

  When there is no storage area where the count number is 30 or more, the measured seismic intensity is 4.0 or less. The purpose here is to measure earthquakes with a seismic intensity of 4.0 or more.

  For example, if you want to determine an earthquake with a seismic intensity of 5.0 or higher, similarly, 21 memory areas are prepared as counters in order to count seismic intensity from seismic intensity 5.0 to seismic intensity 7.0 in increments of 0.1. That's fine.

  Reference is again made to FIG. When the measured seismic intensity calculation unit 16 calculates the measured seismic intensity S by the above calculation, the measured seismic intensity S is output to the seismic intensity determination unit 17. The seismic intensity determination unit 17 determines whether the gas should be shut off based on the input measured seismic intensity S. The seismic intensity determination unit 17 holds a threshold value of the measured seismic intensity S that should block the gas.

  When the seismic intensity determination unit 17 determines that the gas should be shut off, a control signal that instructs the gas cutoff control unit 18 to shut off the gas is output. In response to this signal, the gas cutoff controller 18 performs an operation of closing the gas flow valve.

  As described above, the seismic intensity measurement apparatus 1 according to the present embodiment can execute a filter process approximated to the JMA-defined filter process by a combination of addition, subtraction, and shift calculation. Thereby, low power consumption is realized.

  For example, a low power consumption type device can be developed in a battery-driven device that shuts off gas when an earthquake having a seismic intensity of about 5 or more occurs.

  Moreover, the seismic intensity measuring apparatus 1 of this Embodiment can acquire the measured seismic intensity S by simple calculation according to the resolution. Also by this, the power consumption of the seismic intensity measuring device 1 can be reduced.

  Since the seismic measurement apparatus 1 of the present embodiment performs filter processing and measurement of seismic intensity with a simple circuit configuration, the processing speed can be improved. Suitable for earthquake warning device by P wave detection.

{4. Low power consumption measures}
In order to detect earthquakes with a seismic intensity of 5 or more with a very high probability, it is necessary to perform measurement with an increased sampling rate when the acceleration amplitude of one component, low-speed sampling is about 10 gal or more. However, in a place where the vibration is large, a case where the acceleration amplitude becomes about 10 gal or more frequently occurs.

  In the present embodiment, when the acceleration data of one component becomes equal to or higher than the threshold value E1 during observation at the low sampling rate of f1 Hz, the acceleration data of the one component is observed at the medium sampling rate of f2 Hz. . If the acceleration is less than the threshold value E2 for t1 seconds or longer during medium-speed sampling rate observation, the low-speed sampling rate is restored. Conversely, when the acceleration is equal to or greater than the threshold value E2, three component acceleration data is observed at a 100 Hz sampling rate, and an instantaneous value of seismic intensity is calculated. As a result of observation by 100 Hz sampling, when the state where the instantaneous value is less than the threshold value E3 continues for t2 seconds or more, the medium speed sampling rate is restored. The threshold values f1, f2, E1, E2, E3, t1, and t2 are earthquakes that occurred in the past. Using the waveform data observed by the national strong motion observation network, there is a statistical probability of 100%. Is set to be detected. By optimizing this setting, the observation time of the three components at the medium speed sampling rate or 100 Hz sampling rate can be shortened even in a place where the artificial noise amplitude is large.

The earthquake occurrence detector 19 and the measured seismic intensity calculator 16 shown in FIG. 1 use the waveform data of earthquakes that have occurred in the past to detect the occurrence of earthquakes with a statistically 100% probability and most efficiently. A threshold value is set. Usually, the A / D converter 13 performs A / D conversion on the acceleration data of one component at a low sampling rate and operates in a low power consumption state. The earthquake occurrence detection unit 19 receives the acceleration waveform data A _X (t) output from the A / D converter 13 and determines whether the acceleration is greater than or less than a threshold value. When the acceleration becomes equal to or greater than the threshold value, the earthquake occurrence detection unit 19 notifies the switching unit 20 to perform observation at the medium speed sampling rate. In response to the control signal, the switching unit 20 instructs the A / D converter 13 to change the sampling rate. In the medium-speed sampling rate observation, when the acceleration is equal to or higher than another threshold, the earthquake occurrence detection unit 19 controls the A / D converter 13 to operate at a high sampling rate with respect to three-component acceleration data. To do. When the acceleration amplitude continues for a predetermined period or longer and less than the threshold value, the sampling rate is lowered to a medium or low sampling rate. If the seismic intensity is equal to or greater than the threshold value, 500 Hz sampling is performed for a short time, and the dominant frequency of the waveform data is examined to determine whether it is an earthquake or noise. This operation enables earthquake detection with few malfunctions. By choosing the optimal values for the threshold values f1, f2, E1, E2, E3, t1, and t2, the average is obtained even in places with extremely large vibrations, such as under the bullet train viaduct or under the expressway. With a typical sampling rate of about 2.5 Hz, earthquake detection with a very high probability is possible, and the battery can be used for a long time.

FIG. 5 shows measurement test results under a viaduct near Yurakucho Station. A maximum acceleration of 300 gal was observed. Seismic measuring device 1 of this embodiment detects a large amplitude of the signal, in the interval T _1, X, Y, about 3 component in the Z-direction, entered the seismic intensity measurement mode for data recording at 100Hz sampling.

Then, since the intensity 5 or more measurement results were obtained, in the interval T _2, the data recorded in 500Hz sampling was performed. In the section T _2, she is of the checks have characteristics of dominant frequency and seismic waves was conducted. As a result, it is shown to be noise, the interval T _3, and returned to the data recording by the lower sampling rate again.

{5. Lightning countermeasures}
At the observation points of the earthquake early warnings by the Japan Meteorological Agency, warnings are distributed as earthquakes with a seismic intensity of 5 or more once a year at 200 stations. If many acceleration sensors are installed, lightning countermeasures are considered essential. The vibration due to lightning is attenuated in about 1 to 2 seconds, but the vibration due to the earthquake lasts longer than that. The seismic intensity measuring device 1 of the present embodiment incorporates lightning countermeasures that take this feature into consideration. Specifically, even if the earthquake occurrence detection unit 19 detects an amplitude that exceeds a threshold, if the large amplitude does not continue for a predetermined time, the earthquake occurrence detection unit 19 does not determine that there is an earthquake. Since the bit is turned on while the amplitude exceeds the predetermined threshold and the period during which the bit is on is counted, the processing load is small and the power consumption is not increased.

DESCRIPTION OF SYMBOLS 1 Earthquake measuring device 11 Acceleration sensor 13 A / D converter 14 Filter 15 Amplitude calculating part 16 Measuring seismic intensity calculating part 141 High pass filter 142 (Primary) Recursive filter 143 (Secondary) IIR filter 144 (Secondary) IIR filter

Claims (11)

An acceleration input unit for inputting acceleration waveform data;
A filter that performs filtering on the acceleration waveform data and outputs corrected acceleration waveform data;
A seismic intensity calculation unit for calculating a seismic intensity from the corrected acceleration waveform data;
With
The seismic intensity measuring device, wherein the filter converts the acceleration waveform data into the corrected acceleration waveform data by combining an addition circuit, a subtraction circuit, and a bit shift operation circuit. An acceleration input unit for inputting acceleration waveform data;
A filter that performs filtering on the acceleration waveform data and outputs corrected acceleration waveform data;
A seismic intensity calculation unit for calculating a seismic intensity from the corrected acceleration waveform data;
With
The filter converts the acceleration waveform data into the corrected acceleration waveform data by performing a combination of addition, subtraction, multiplication of powers of two, division of powers of 2 and division of power. measuring device. In the seismic intensity measuring device according to claim 1 or 2,
The filter is
A high-pass filter,
A low pass filter,
Seismic intensity measuring device characterized by including. In the seismic intensity measuring device according to claim 3,
The high-pass filter has a differential filter that performs an operation represented by Equation (1),
A ₁ is a seismic intensity measuring device characterized in that it is a constant of a power of 2 set in consideration of a digit loss in integer arithmetic.
Where t is time, X (t) is acceleration waveform data, and Y ₁ (t) is the output of the differential filter.

In the seismic intensity measuring device according to claim 3,
The low-pass filter includes a recursible filter that performs an operation represented by Formula 2,
G ₁ is a power of 2 and is a seismic intensity measuring device.
However, t is _{time, Y} 1 (t) is the input of recursive Le _{filter, Y} 2 (t) is the output of the recursive Le filter.

In the seismic intensity measuring device according to claim 3,
The low pass filter is
A first IIR filter that performs the operations shown in Equation 3 and Equation 4;
A second IIR filter that performs the operations shown in Equation 5 and Equation 6,
Have
G ₂ , G ₃ , G ₄ and G ₅ are powers of 2, and the seismic intensity measuring device.
Where t is time, Y ₂ (t) is the input of the first IIR filter, and D ₁ (t) is the feedback term of the first IIR filter. D ₂ (t) is the output of the first IIR filter and the input of the second IIR filter. D ₃ (t) is a feedback term of the second IIR filter, and D ₄ (t) is an output of the second IIR filter.

An acceleration input unit for inputting acceleration waveform data;
A filter that performs filtering on the acceleration waveform data and outputs corrected acceleration waveform data;
A seismic intensity calculation unit for calculating a seismic intensity from the corrected acceleration waveform data;
With
The seismic intensity calculation unit
When the corrected acceleration waveform data in the X, Y, and Z3 directions is H _X (t), H _Y (t), and H _Z (t), W (t) is obtained by performing the calculation shown in Formula 7. A first seismic intensity calculation unit to be obtained;

By changing S (t) shown in Equation 8 to W (t) = 2 ^{A (t)} , it is transformed into Equation 9;

When A (t) with seismic intensity N is A ₀ = 10 (N−0.94 + 2 log (C * A)), and W (t) ⁶ is expressed in binary, the number of digits of the maximum bit is B _N (t ), The second seismic intensity measurement unit for obtaining the seismic intensity S (t) by performing the calculation represented by Equation 10;
Seismic intensity measuring device characterized by including.

However, the number 10 formula, _{S B} is the reference seismic intensity. The seismic intensity measuring device according to claim 7, further comprising:
The second seismic S measured by the seismic intensity measuring portion (t) is more than 0.3 seconds, the maximum value determination unit for outputting a maximum value S _m of the values of S _a when the above S _a as seismic intensity,
A seismic intensity measuring device comprising: In the seismic intensity measuring device according to any one of claims 1 to 8,
An A / D converter for A / D converting acceleration waveform data input to the acceleration input unit;
A sampling rate determining unit for determining a sampling rate of the A / D converter;
With
The sampling rate determining unit
An earthquake occurrence detector that detects an earthquake at a threshold of different acceleration according to the acceleration observed by the seismic intensity measurement device;
According to the detection result of the earthquake occurrence detection unit, a switching unit for switching the sampling rate of the A / D converter,
A seismic measuring device comprising: In the earthquake measuring device according to any one of claims 1 to 9,
The seismic intensity measurement apparatus characterized by canceling the measurement as an earthquake when the duration of the seismic intensity calculated by the seismic intensity calculation unit is shorter than a predetermined time. The earthquake measurement device according to any one of claims 1 to 10, further comprising:
When the seismic intensity calculated by the seismic intensity calculation unit exceeds a predetermined threshold, a gas cutoff control unit that controls to shut off the gas,
An earthquake measuring apparatus comprising:

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