JP7455055B2 - Wave amplitude estimation method, amplitude estimation device, and program - Google Patents

Description

The present invention relates to a wave amplitude estimation method, an amplitude estimation device, and a program.

Wave height meters are used to monitor water level fluctuations in real time in the sea area near construction sites. There are various types of wave height meters, such as submarine-mounted types, aerial radiation types, and buoy types.

A seabed-mounted wave height meter is a wave height meter that uses ultrasonic irradiation equipment, water pressure sensors, etc. from the seabed to measure water surface fluctuations. Seabed-mounted wave height meters require a diver to install them, making them difficult to install at great depths. Furthermore, since the ultrasonic irradiation equipment and water pressure sensors are located on the seabed, they must be connected via cable to transmit observation data to the offshore work boat.

Airborne wave height meters emit ultrasonic waves from the air toward the water surface and detect changes in the water surface from the reflections. However, if the work boat sways, it is necessary to take that sway into account. Furthermore, since it is necessary to radiate the ultrasonic wave at a right angle toward the water surface, it is difficult to maintain the radiation angle of the ultrasonic wave at a right angle due to the movement of the ship.

A buoy-type wave height meter is a wave height meter that uses a buoy (also called a buoy) suspended on the water surface to measure water surface fluctuations. Buoy-type wave height meters include those that use a Global Navigation Satellite System (GNSS) and those that use an acceleration sensor.

Buoy-type wave height meters that use GNSS can obtain altitude information from GNSS, but depending on the required accuracy, the materials and equipment tend to be large.

A buoy-type wave height meter that uses an acceleration sensor measures vertical acceleration with an acceleration sensor attached to a buoy, and estimates water level fluctuations by double integrating this acceleration over time.

For example, Patent Document 1 describes a wave observation device configured to integrate the output of an acceleration sensor to obtain a velocity component, or further integrate the velocity component to obtain a displacement component. A wave observation device using an acceleration sensor is described, which is characterized in that a trend component superimposed on the component or displacement component is removed by passing the component or displacement component through a high-pass filter having a required passband. ing.

Japanese Unexamined Patent Publication No. 61-212716

However, in order to estimate water level fluctuations using a method that double-integrates acceleration over time, a relatively highly accurate acceleration sensor is required.

One of the objects of the invention of the present application is to calculate the amplitude of waves without integrating acceleration time series data that shows changes over time in measured values of vertical acceleration that floating objects on water receive due to vertical movement of the water surface. is to estimate.

The amplitude estimation method according to claim 1 of the present invention includes an acceleration acquisition step of acquiring acceleration time series data indicating a change over time in a measured value of vertical acceleration that a floating object floating on water receives due to vertical movement of the water surface;
an acceleration frequency spectrum identification step of identifying a frequency spectrum of acceleration that changes over time indicated by the acceleration time series data;
The frequency spectrum of the acceleration specified in the acceleration frequency spectrum identification step according to the relationship between the intensity of the frequency spectrum of the water level that changes over time at the same frequency and the intensity of the frequency spectrum of the acceleration that changes over time that a floating object floating on the water at the water level receives a water level frequency spectrum identification step of identifying a water level frequency spectrum according to the water level;
a frequency-by-frequency energy ratio identifying step of identifying the ratio of energy for each frequency to the total energy as the water level changes over time from the water level frequency spectrum identified in the water level frequency spectrum identifying step;
The energy ratio for each frequency specified in the energy ratio identification step for each frequency is multiplied by the relationship between the amplitude of the acceleration time series and the water level time series specified for each frequency according to the relationship between the amplitude of water level and acceleration. a conversion coefficient calculation step of calculating a conversion coefficient by summing all frequencies after calculating the value;
an amplitude estimation step of estimating the amplitude of the wave indicated by the water level by multiplying the acceleration time series data by a conversion coefficient that is the sum of all frequencies;
This is a wave amplitude estimation method comprising:

In the amplitude estimation method according to claim 2 of the present invention, in the aspect described in claim 1, the intensity of the frequency spectrum of a water level that changes over time at the same frequency and the acceleration that changes over time that floating objects floating on the water at the water level are subjected to. The relationship between the intensity of the frequency spectrum is that the intensity of the frequency spectrum of the water level is the value obtained by multiplying the intensity of the frequency spectrum of acceleration by the fourth power of the period, divided by the fourth power of pi and 16. This is the amplitude estimation method used.

The amplitude estimation method according to claim 3 of the present invention, in the aspect described in claim 1 or 2, includes the amplitude of a water level that changes over time at the same frequency and the amplitude of acceleration that changes over time that a floating object floating on the water at the water level receives. Amplitude estimation using the relationship that the ratio between the amplitude of the water level and the amplitude of the acceleration of the water level is the reciprocal of the square of the frequency of the water level multiplied by the square of pi and 4. It's a method.

The amplitude estimating device according to claim 4 of the present invention includes an acceleration acquisition means for acquiring acceleration time series data indicating a change over time in a measured value of vertical acceleration that a floating object floating on water receives due to vertical movement of the water surface;
Acceleration frequency spectrum specifying means for specifying a frequency spectrum of acceleration that changes over time indicated by the acceleration time series data;
A frequency spectrum of acceleration specified by the acceleration frequency spectrum specifying means according to the relationship between the intensity of the frequency spectrum of the water level that changes over time at the same frequency and the intensity of the frequency spectrum of the acceleration that changes over time that a floating object floating on the water at the water level receives water level frequency spectrum identification means for identifying a water level frequency spectrum according to the water level;
Frequency-by-frequency energy ratio specifying means for specifying the ratio of energy for each frequency to the total energy as the water level changes over time from the frequency spectrum of the water level specified by the water level frequency spectrum specifying means;
The energy ratio for each frequency specified by the energy ratio identification means for each frequency is multiplied by the relationship between the amplitude of the acceleration time series and the water level time series specified for each frequency according to the relationship between the amplitude of water level and acceleration. Conversion coefficient calculation means for calculating a conversion coefficient by summing all frequencies after calculating the value;
amplitude estimating means for estimating the amplitude of a wave indicated by the water level by multiplying the acceleration time series data by a conversion coefficient that is the sum of all frequencies;
This is a wave amplitude estimation device comprising:

A program according to claim 5 of the present invention includes a process of causing a computer to acquire acceleration time series data indicating a change over time of a measured value of vertical acceleration that a floating object on water receives due to vertical movement of the water surface;
A process of identifying the frequency spectrum of acceleration that changes over time indicated by the acceleration time series data, the intensity of the frequency spectrum of the water level that changes over time at the same frequency, and the frequency spectrum of the acceleration that changes over time that is received by floating objects floating on the water at the water level. A process of identifying a frequency spectrum of a water level according to a frequency spectrum of the acceleration identified in the process of identifying the frequency spectrum of the acceleration, according to an intensity relationship of;
From the frequency spectrum of the water level identified in the process of identifying the frequency spectrum of the water level, a process of identifying the ratio of energy for each frequency to the total energy as the water level changes over time;
The energy ratio for each frequency specified in the energy ratio identification step for each frequency is multiplied by the relationship between the amplitude of the acceleration time series and the water level time series specified for each frequency according to the relationship between the amplitude of water level and acceleration. After calculating the value, a process of calculating a conversion coefficient by summing all frequencies; and a process of estimating the amplitude of the wave indicated by the water level by multiplying the acceleration time series data by a conversion coefficient that is the sum of all frequencies. ,
This is a program to run.

According to the present invention, wave amplitude can be estimated without integrating acceleration time-series data that indicates changes over time in measured values of vertical acceleration that floating objects on water receive due to vertical movement of the water surface. I can do it.

1 is a schematic diagram showing an example of the overall configuration of an amplitude estimation system 9. FIG. FIG. 1 is a diagram showing an example of the configuration of an amplitude estimating device 1. FIG. FIG. 2 is a diagram showing an example of the configuration of a terminal 2. FIG. 1 is a diagram showing an example of a functional configuration of an amplitude estimating device 1. FIG. FIG. 2 is a flow diagram showing an example of the flow of operation of the amplitude estimating device 1. FIG. FIG. 3 is a diagram showing an example of time-series data acquired by the amplitude estimating device 1. FIG. FIG. 3 is a diagram showing an example of a frequency spectrum specified by the amplitude estimating device 1. FIG. A diagram showing an example of energy ratio for each frequency. A diagram showing an example of estimated water levels.

<Overall configuration of amplitude estimation system>
FIG. 1 is a schematic diagram showing an example of the overall configuration of an amplitude estimation system 9. As shown in FIG. The amplitude estimation system 9 includes an amplitude estimation device 1 and a terminal 2. Further, the amplitude estimation system 9 shown in FIG. 1 includes a communication line 3.

The water surface Lv is the water surface of a sea or a lake, and moves up and down in the vertical direction due to the action of waves. The floating object J is a structure such as a buoy floating on the water. The floating objects J move in the vertical direction as the water surface Lv moves up and down.

The terminal 2 is attached to the floating object J. Therefore, the terminal 2 receives a vertical force due to the vertical movement of the water surface Lv together with the floating object J. The terminal 2 has a function of measuring at least vertical acceleration, generates acceleration time series data indicating changes over time in the measured value of this acceleration, and supplies this to the amplitude estimating device 1.

The amplitude estimation device 1 is an information processing device, for example a computer, that estimates the amplitude of waves occurring on the water surface Lv. The amplitude estimation device 1 acquires the above-mentioned acceleration time series data from the terminal 2. The amplitude estimation device 1 then identifies the frequency spectrum of the acceleration indicated by the acquired acceleration time series data, and uses the identified frequency spectrum of the acceleration to identify the corresponding frequency spectrum of the water level according to a predetermined relationship, identifies the ratio of the energy for each frequency to the total energy associated with the change in the water level over time, calculates a conversion coefficient, and estimates the amplitude of the waves from the acceleration time series data.

The communication line 3 is a line that wirelessly connects the amplitude estimation device 1 and the terminal 2 to enable communication. The terminal 2 transmits the acceleration time series data generated by itself to the amplitude estimating device 1 via this communication line 3. The communication line 3 may be, for example, a line using LPWA (Low Power Wide Area).

Examples of this LPWA include "ELTRES (registered trademark)," "LoRa (registered trademark)," "LoRaWAN (registered trademark)," "RPMA (registered trademark)," "SIGFOX (registered trademark)," and "EnOcean (registered trademark)." Long Range”, “NB-IoT”, “NB-Fi Protocol”, “GreenOFDM”, “DASH7”, “Wi-SUN”, “Weightless-P”, “LTE-MTC”, “LTE Cat. 0", "LTE Cat.M1", etc.

<Configuration of amplitude estimation device>
FIG. 2 is a diagram showing an example of the configuration of the amplitude estimating device 1. The amplitude estimating device 1 includes a processor 11, a memory 12, and an interface 13. The processor 11 controls the amplitude estimating device 1 by executing a computer program (hereinafter simply referred to as a program) stored in the memory 12. The processor 11 is, for example, a CPU (Central Processing Unit).

The interface 13 is an interface through which the processor 11 exchanges information with the communication line 3 and other external devices.

The processor 11 connects to the communication line 3 via the interface 13 and acquires acceleration time series data generated by the terminal 2 from the communication line 3.

Further, the amplitude estimating device 1 is connected to, for example, an external display device via the interface 13, and displays the determined information to the user.

The memory 12 is a storage means such as a RAM (Random Access Memory), a ROM (Read Only Memory), a solid state drive, a hard disk drive, etc., and stores an operating system read into the processor 11, various programs, data, and the like.

<Terminal configuration>
FIG. 3 is a diagram showing an example of the configuration of the terminal 2. As shown in FIG. The terminal 2 includes a processor 21, a memory 22, an interface 23, and an acceleration sensor 26.

Processor 21 controls terminal 2 by executing programs stored in memory 22. The processor 21 is, for example, a CPU.

The interface 23 is an interface through which the processor 21 exchanges information with the communication line 3 and other external devices.

The processor 21 is connected to the communication line 3 via the interface 23 and transmits acceleration time series data to the amplitude estimating device 1 via the communication line 3.

Further, the terminal 2 may be connected to an external storage device such as a flash memory via the interface 23, and store acceleration time series data and the like in this storage device.

The memory 22 is a storage means such as a RAM, ROM, solid state drive, hard disk drive, etc., and stores an operating system read into the processor 21, various programs, data, and the like.

The acceleration sensor 26 is, for example, a sensor that measures acceleration using a MEMS (Micro Electro Mechanical Systems) method. The acceleration sensor 26 measures at least the vertical acceleration that it receives and sequentially stores it in the memory 22. As a result, acceleration time-series data is generated in the memory 22, which indicates changes over time in the measured acceleration in the vertical direction. This generated acceleration time series data is transmitted to the amplitude estimating device 1 as described above. Note that since the terminal 2 is attached to the floating object J, the acceleration measured by the processor 21 is the acceleration that the terminal 2 receives as well as the acceleration that the floating object J receives.

<Functional configuration of amplitude estimation device>
FIG. 4 is a diagram showing an example of the functional configuration of the amplitude estimating device 1. The processor 11 of the amplitude estimating device 1 executes the above-mentioned program to obtain an acceleration acquisition means 111, an acceleration frequency spectrum identification means 112, a water level frequency spectrum identification means 113, an energy ratio per frequency identification means 114, and a conversion coefficient calculation means 115. , and functions as the amplitude estimating means 116.

The acceleration acquisition means 111 acquires the above-mentioned acceleration time series data from the terminal 2 via the interface 13. That is, this acceleration acquisition means 111 is an example of an acceleration acquisition means that acquires acceleration time-series data indicating a change over time in a measured value of vertical acceleration that a floating object floating on water receives due to vertical movement of the water surface.

The acceleration frequency spectrum specifying means 112 reads the acceleration time series data acquired by the acceleration acquisition means 111 and stored in the memory 12, and specifies the frequency spectrum of acceleration indicated by this acceleration time series data in a predetermined period. This predetermined period is, for example, 20 minutes. In this case, the acceleration frequency spectrum specifying means 112 cuts out 20 minutes of acceleration time series data and calculates its frequency spectrum using various spectrum analysis algorithms such as fast Fourier transform. That is, the acceleration frequency spectrum specifying means 112 is an example of an acceleration frequency spectrum specifying means that specifies the frequency spectrum of acceleration that changes over time, which is indicated by the acceleration time series data. Although the predetermined period is 20 minutes, it is not limited to 20 minutes, and may be any period of time that corresponds to about 100 waves. For example, if the wave period is estimated to be about 6 seconds, this predetermined period may be about 10 to 20 minutes.

The water level frequency spectrum specifying means 113 determines a predetermined relationship, such as the ratio of the frequency spectrum between the water level and its acceleration, with respect to the intensity of the frequency spectrum of the acceleration that changes over time, which a floating object floating on water at a certain water level receives. is used to identify the intensity of the frequency spectrum of that water level that changes over time at the same frequency.

That is, this water level frequency spectrum specifying means 113 determines the acceleration frequency spectrum according to the relationship between the intensity of the frequency spectrum of the water level that changes over time at the same frequency and the intensity of the frequency spectrum of the acceleration that changes over time that floating objects floating on the water at this water level receive. This is an example of a water level frequency spectrum specifying means that specifies a frequency spectrum of a water level corresponding to a frequency spectrum of acceleration specified by the specifying means.

For example, the ratio between the intensity of the frequency spectrum of water level fluctuation and the intensity of the frequency spectrum of acceleration is (T/2π) ⁴ (T is period and π is pi). This (T/2π) ⁴ is T ⁴ /(16π ⁴ ). When using this, the above-mentioned relationship used by the water level frequency spectrum specifying means 113 is such that the intensity of the frequency spectrum of the water level is equal to the value obtained by multiplying the intensity of the frequency spectrum of acceleration by the fourth power of the period to the fourth power of pi. and 16.

In this case, the processor 11 functioning as the water level frequency spectrum specifying means 113 calculates the intensity of the frequency spectrum of the water level that changes over time at the same frequency and the intensity of the frequency spectrum of the acceleration that changes over time that floating objects floating on the water at this water level receive. As a relationship, the intensity of the frequency spectrum of the water level is the value obtained by multiplying the intensity of the frequency spectrum of acceleration by the fourth power of the period divided by the fourth power of pi and 16. be.

The frequency-by-frequency energy ratio specifying means 114 determines the total energy E _all accompanying the change in water level over time from the frequency spectrum of the water level specified by the water level frequency spectrum specifying means 113. Further, the frequency-by-frequency energy ratio specifying means 114 decomposes the frequency spectrum of the water level described above into each frequency, and obtains the energy Ef for each frequency (indicated by "f"). Then, the frequency-by-frequency energy ratio specifying means 114 specifies the ratio of the above-mentioned energy for each frequency to the above-mentioned total energy, that is, a(f)=Ef/E _all .

In other words, the per-frequency energy ratio specifying means 114 specifies the ratio of energy for each frequency to the total energy as the water level changes over time from the frequency spectrum of the water level specified by the water level frequency spectrum specifying means. This is an example of means.

The conversion coefficient calculation means 115 calculates a conversion coefficient (hereinafter also referred to as A _spc ) used for estimating time series data of water level from time series data of acceleration. First, the conversion coefficient calculating means 115 multiplies the energy ratio for each frequency (that is, a(f)) specified by the per-frequency energy ratio specifying means 114 by the ratio of the amplitude of the water level and the amplitude of the acceleration of the water level. Then, calculate the value for each frequency.

Here, the relationship between the frequency f and the period T is f=1/T. Further, "the ratio between the amplitude of the water level that changes over time at a certain frequency f and the amplitude of the acceleration of the water level" is (T/2π) ² (T is the period and π is the constant of pi). Therefore, the conversion coefficient calculation means 115 calculates a(1/T)×(T/2π) ² as the above-mentioned value for each frequency f.

When the above-mentioned formula is expressed in terms of frequency f, it is a(f)×(1/(f·2π)) ² , which is equal to a(f)×(1/(f ² ·4·π ² )). In other words, the above-mentioned value calculated by the conversion coefficient calculating means 115 for each frequency f is obtained by multiplying the energy ratio a(f) for each frequency by the reciprocal of the value obtained by multiplying the square of the frequency by the square of pi and 4. This is the value.

Therefore, the relationship between the amplitude of the water level that changes over time at the same frequency and the amplitude of the acceleration that changes over time that floating objects floating on the water at this water level, which is used by this conversion coefficient calculation means 115 to calculate the above-mentioned value, is as follows. The ratio between the amplitude of the water level and the amplitude of the acceleration of this water level is the reciprocal of the value obtained by multiplying the square of the frequency of this water level by the square of pi and 4.

After calculating the above-mentioned values for each frequency, the conversion coefficient calculation means 115 sums up all these values to calculate A _spc , which is a conversion coefficient.

In other words, the conversion coefficient calculation means 115 converts the energy ratio for each frequency specified by the energy ratio per frequency identification means into the amplitude of the acceleration time series and water level time series specified for each frequency according to the relationship between the amplitude of water level and acceleration. This is an example of a conversion coefficient calculation means that calculates a conversion coefficient by calculating a value for each frequency by multiplying by the relationship, and then summing the values for all frequencies.

The amplitude estimation means 116 multiplies the acceleration time series data acquired by the acceleration acquisition means 111 by the conversion coefficient calculated by the conversion coefficient calculation means 115 to estimate water level fluctuation time series data. This estimated water level fluctuation time series data is used to estimate the amplitude of the wave indicated by the water level that is the source of the acceleration time series data.

In other words, the amplitude estimating means 116 is an example of an amplitude estimating means that multiplies the acceleration time series data by a conversion coefficient that is the sum of all frequencies to estimate the amplitude of the wave indicated by the water level.

Information on the wave amplitude estimated by the amplitude estimating means 116 is displayed via the interface 13, for example, on an external display device.

<Operation of amplitude estimation device>
FIG. 5 is a flow diagram showing an example of the flow of operation of the amplitude estimating device 1. The processor 11 of the amplitude estimating device 1 acquires acceleration time series data (step S101), and calculates the change over time of the acceleration indicated by the acquired acceleration time series data over a predetermined period (for example, 20 minutes, etc.). , performs spectrum analysis (step S102).

Note that step S101 described above is an example of an acceleration acquisition step of acquiring acceleration time-series data indicating a change over time in a measured value of vertical acceleration that a floating object floating on water receives due to vertical movement of the water surface.

Further, step S102 described above is an example of an acceleration frequency spectrum specifying step of specifying a frequency spectrum of acceleration that changes over time, which is indicated by the acceleration time series data.

FIG. 6 is a diagram showing an example of time series data acquired by the amplitude estimating device 1. The horizontal axis shown in FIG. 6 shows time, and the vertical axis shows acceleration. For example, the processor 11 performs Fourier transform on the 20-minute acceleration time series data shown in FIG. 6 to identify its frequency spectrum. Note that the acceleration time series data shown in FIG. 6 is data whose polarity is reversed by multiplying the actually measured acceleration by -1.

FIG. 7 is a diagram showing an example of a frequency spectrum specified by the amplitude estimating device 1. The horizontal axis shown in FIG. 7 shows frequency, and the vertical axis shows spectral intensity. In addition, in the figure, the numerical units indicated by the vertical and horizontal axes of the frequency spectrum are omitted. The curve shown by the broken line in FIG. 7 is a graph obtained by converting the acceleration time series data shown in FIG. 6 into a frequency spectrum. The processor 11 calculates the water level according to the frequency spectrum of the acceleration according to the relationship between the intensity of the frequency spectrum of the water level that changes over time at the same frequency and the intensity of the frequency spectrum of the acceleration that changes over time that floating objects floating on the water at that water level receive. A frequency spectrum is specified (step S103).

For example, the processor 11 multiplies the curve shown by the broken line in FIG. 7 by the ratio of (T/2π) ⁴ described above to obtain the curve shown by the solid line in FIG. The curve shown by this solid line represents the frequency spectrum of the water level according to the frequency spectrum of acceleration.

That is, step S103 described above is an acceleration frequency spectrum specifying step according to the relationship between the intensity of the frequency spectrum of the water level that changes over time at the same frequency and the intensity of the frequency spectrum of the acceleration that changes over time and is received by floating objects floating on the water at that water level. This is an example of a water level frequency spectrum specifying step of specifying a water level frequency spectrum corresponding to a specified frequency spectrum of acceleration.

Next, the processor 11 specifies the energy ratio for each frequency based on the frequency spectrum of the specified water level (step S104). In this step, the amplitude estimating device 1 calculates E _all , which is the total energy of the water level frequency spectrum specified in step S103. Furthermore, the processor 11 calculates Ef, which is the energy for each frequency f, in this water level frequency spectrum.

FIG. 8 is a diagram showing an example of energy ratio for each frequency. The horizontal axis shown in FIG. 8 shows frequency, and the vertical axis shows spectral intensity. The solid line shown in FIG. 8 is a line representing the frequency spectrum of the water level determined in FIG. The area of the surface surrounded by this is the so-called frequency integral of the frequency spectrum of the water _level . show. On the other hand, the area inside the rectangle shown in FIG. 8 indicates, for example, wave energy Ef at a certain frequency f.

Then, the processor 11 specifies the ratio of energy for each frequency f to the total energy by calculating Ef/E _all .

In other words, step S104 described above is an example of a frequency-by-frequency energy ratio specifying step that specifies the ratio of energy for each frequency to the total energy as the water level changes over time from the frequency spectrum of the water level specified in the water level frequency spectrum specifying step. be.

Once the above-mentioned ratio is specified, the processor 11 calculates a conversion coefficient using this ratio (step S105). In this step, the processor 11 first multiplies the above-mentioned energy ratio for each frequency by the relationship between the amplitude of the acceleration time series and the water level time series, which is specified for each frequency according to the relationship between the amplitude of the water level and the acceleration, and calculates the ratio for each frequency. Calculate the value of Then, the processor 11 calculates a conversion coefficient by summing these calculated values over all frequencies.

In other words, in step S105 described above, the energy ratio for each frequency specified in the energy ratio identification step for each frequency is calculated based on the amplitude of the acceleration time series and water level time series specified for each frequency according to the relationship between the amplitude of water level and acceleration. This is an example of a conversion coefficient calculation step in which a value for each frequency is calculated by multiplying by the relationship, and then a conversion coefficient is calculated by summing up all frequencies.

Then, the processor 11 multiplies the acceleration time series data acquired in step S101 by the conversion coefficient calculated in step S105 to estimate the water level, that is, the amplitude of the wave, according to the acceleration indicated by this acceleration time series data ( Step S106).

FIG. 9 is a diagram showing an example of estimated water levels. The horizontal axis in FIG. 9 indicates time, and the vertical axis indicates acceleration or water level. The curve shown by the broken line in FIG. 9 corresponds to the curve shown by the solid line in FIG. 6, and shows time-series data of acceleration in a predetermined period. The processor 11 multiplies this acceleration time series data by the conversion coefficient obtained through the above-described operation to estimate the corresponding water level. The estimated water level (referred to as estimated water level) is shown by a solid line in FIG. The curve shown by the dashed line in FIG. 9 is the actual water level. This water level is not actually measured by the amplitude estimating device 1, but is illustrated to confirm the accuracy, tendency, etc. of the estimated water level estimated by the amplitude estimating device 1. As a result, the estimated water level changes according to the actual water level, and can be regarded as the water level in practical terms.

That is, this step S106 is an example of an amplitude estimation step of estimating the amplitude of the wave indicated by the water level by multiplying the acceleration time series data by a conversion coefficient that is the sum of all frequencies. Note that in step S106, the processor 11 transmits, for example, information indicating the estimated amplitude to an external display device or the like via the interface 13, and displays the information.

Then, the processor 11 determines whether the termination condition for the process executed by the amplitude estimating device 1 is satisfied (step S107). The termination condition is, for example, that an instruction to terminate the process has been received from the user. When determining that the termination condition is satisfied (step S107; YES), the processor 11 terminates the process. On the other hand, if it is determined that the end condition is not satisfied (step S107; NO), the processor 11 returns the process to step S101.

Through the above-described operations, the amplitude estimating device 1 identifies the energy of a wave that has struck during a predetermined period of time, such as 20 minutes, and estimates time-series water level data representing the wave. Therefore, if the amplitude estimating device 1 acquires time-series data that measures the acceleration of water surface fluctuations, it can obtain time-series data of the water level and, for example, obtain estimated values of wave amplitude and wave height. evaluation becomes possible.

<Modified example>
The above is the description of the embodiment, but the content of this embodiment can be modified as follows. Further, the following modifications may be combined.

<1>
In the embodiment described above, the terminal 2 had the acceleration sensor 26, but the terminal 2 does not need to have the acceleration sensor 26 as long as the acceleration in the vertical direction of the water surface Lv can be measured along the time axis. Moreover, although the terminal 2 was attached to the floating object J, the terminal 2 itself may be configured to float on water.

<2>
In the embodiment described above, the amplitude estimating device 1 and the terminal 2 are connected to each other via the communication line 3 and exchange information, but even if they exchange information without going through the communication line 3, good. For example, the interface 13 of the amplitude estimating device 1 and the interface 23 of the terminal 2 both have a short-range wireless communication function, and this short-range wireless communication allows the amplitude estimating device 1 and the terminal 2 to exchange information. You can interact.

Further, the amplitude estimating device 1 does not need to acquire acceleration time series data from the terminal 2 in real time. For example, the amplitude estimating device 1 may acquire the acceleration time series data stored in the memory 22 of the terminal 2 via the interface 23 and a wired cable connecting the interface 13. Further, the terminal 2 may copy the acceleration time series data stored in the memory 22 to an external flash memory or the like via the interface 23. In this case, the amplitude estimating device 1 may obtain a copy of the above-mentioned acceleration time series data from a flash memory or the like.

<3>
The program executed by the processor 11 described above is stored in a computer-readable recording medium such as a magnetic recording medium such as a magnetic tape and a magnetic disk, an optical recording medium such as an optical disk, a magneto-optical recording medium, or a semiconductor memory. It can be provided in the same condition. Further, this program may be downloaded via a communication line such as the Internet. That is, this program includes a process for a computer to acquire acceleration time series data indicating changes over time in measured values of vertical acceleration that floating objects floating on water receive due to vertical movement of the water surface, and a process for acquiring acceleration time series data indicating changes over time in measured values of vertical acceleration that floating objects floating on water receive due to vertical movement of the water surface. According to the process of identifying the frequency spectrum of acceleration that changes over time, and the relationship between the intensity of the frequency spectrum of the water level that changes over time at the same frequency and the intensity of the frequency spectrum of the acceleration that changes over time, which is received by floating objects floating on the water at the water level, From the process of specifying the frequency spectrum of the water level corresponding to the frequency spectrum of the acceleration specified in the process of specifying the frequency spectrum of acceleration, and the frequency spectrum of the water level specified in the process of specifying the frequency spectrum of the water level, the change in water level over time is determined. The energy ratio for each frequency specified in the energy ratio identification step for each frequency is specified for each frequency according to the relationship between the water level and the amplitude of acceleration. A process of calculating the value for each frequency by multiplying the relationship between the amplitudes of the acceleration time series and water level time series, and then summing up all frequencies to calculate a conversion coefficient, and converting the acceleration time series data by summing all frequencies. This is a program for executing a process of estimating the amplitude of a wave indicated by the water level by multiplying by a coefficient. Note that various devices other than the CPU may be applied as the control means exemplified by the above-mentioned amplitude estimating device; for example, a dedicated processor or the like may be used.

DESCRIPTION OF SYMBOLS 1... Amplitude estimation device, 11... Processor, 111... Acceleration acquisition means, 112... Acceleration frequency spectrum identification means, 113... Water level frequency spectrum identification means, 114... Frequency-specific energy ratio identification means, 115... Conversion coefficient calculation means, 116... Amplitude estimation means, 12...Memory, 13...Interface, 2...Terminal, 21...Processor, 22...Memory, 23...Interface, 26...Acceleration sensor, 3...Communication line, 9...Amplitude estimation system, Lv...Water surface, J... floating objects.

Claims (5)

an acceleration acquisition step of acquiring acceleration time series data indicating changes over time in measured values of vertical acceleration that floating objects floating on water receive due to vertical movement of the water surface;
an acceleration frequency spectrum identification step of identifying a frequency spectrum of acceleration that changes over time indicated by the acceleration time series data;
The frequency spectrum of the acceleration specified in the acceleration frequency spectrum identification step according to the relationship between the intensity of the frequency spectrum of the water level that changes over time at the same frequency and the intensity of the frequency spectrum of the acceleration that changes over time that a floating object floating on the water at the water level receives a water level frequency spectrum identification step of identifying a water level frequency spectrum according to the water level;
a frequency-by-frequency energy ratio identifying step of identifying the ratio of energy for each frequency to the total energy as the water level changes over time from the water level frequency spectrum identified in the water level frequency spectrum identifying step;
The energy ratio for each frequency specified in the energy ratio identification step for each frequency is multiplied by the relationship between the amplitude of the acceleration time series and the water level time series specified for each frequency according to the relationship between the amplitude of water level and acceleration. a conversion coefficient calculation step of calculating a conversion coefficient by summing up all frequencies after calculating the value;
an amplitude estimation step of estimating the amplitude of the wave indicated by the water level by multiplying the acceleration time series data by a conversion coefficient that is the sum of all frequencies;
A wave amplitude estimation method comprising: As the relationship between the intensity of the frequency spectrum of the water level that changes over time at the same frequency and the intensity of the frequency spectrum of the acceleration that changes over time to the floating object floating on the water at the water level, the intensity of the frequency spectrum of the water level is equal to the intensity of the frequency spectrum of acceleration. 2. The amplitude estimation method according to claim 1, wherein a relationship is used in which the value obtained by multiplying the period by the fourth power is divided by the fourth power of pi and 16. As a relationship between the amplitude of the water level that changes over time at the same frequency and the amplitude of the acceleration that changes over time that floating objects floating on the water at that water level receive, the ratio between the amplitude of the water level and the amplitude of the acceleration of the water level is the frequency of the water level in question. 3. The amplitude estimation method according to claim 1, wherein the relationship is the reciprocal of a value obtained by multiplying the square of pi by 4. Acceleration acquisition means for acquiring acceleration time-series data indicating changes over time in measured values of vertical acceleration that floating objects floating on water receive due to vertical movement of the water surface;
Acceleration frequency spectrum specifying means for specifying a frequency spectrum of acceleration that changes over time indicated by the acceleration time series data;
A frequency spectrum of acceleration specified by the acceleration frequency spectrum specifying means according to the relationship between the intensity of the frequency spectrum of the water level that changes over time at the same frequency and the intensity of the frequency spectrum of the acceleration that changes over time that a floating object floating on the water at the water level receives water level frequency spectrum identification means for identifying a water level frequency spectrum according to the water level;
Frequency-by-frequency energy ratio specifying means for specifying the ratio of energy for each frequency to the total energy as the water level changes over time from the frequency spectrum of the water level specified by the water level frequency spectrum specifying means;
A value for each frequency is obtained by multiplying the energy ratio for each frequency specified by the energy ratio per frequency specifying means by the relationship between the amplitude of the acceleration time series and the water level time series specified for each frequency according to the relationship between the amplitude of water level and acceleration. a conversion coefficient calculating means for calculating a conversion coefficient by summing all frequencies after calculating the
amplitude estimating means for estimating the amplitude of a wave indicated by the water level by multiplying the acceleration time series data by a conversion coefficient that is the sum of all frequencies;
A wave amplitude estimation device comprising: to the computer,
A process of acquiring acceleration time-series data indicating changes over time in measured values of vertical acceleration that floating objects floating on water receive due to vertical movement of the water surface;
A process of identifying a frequency spectrum of acceleration that changes over time indicated by the acceleration time series data;
According to the relationship between the intensity of the frequency spectrum of the water level that changes over time at the same frequency and the intensity of the frequency spectrum of the acceleration that changes over time that floating objects floating on the water at the water level receive, the acceleration specified in the process of identifying the frequency spectrum of the acceleration. A process for identifying the frequency spectrum of water level according to the frequency spectrum;
From the frequency spectrum of the water level identified in the process of identifying the frequency spectrum of the water level, a process of identifying the ratio of energy for each frequency to the total energy as the water level changes over time;
The energy ratio for each frequency specified in the energy ratio identification step for each frequency is multiplied by the relationship between the amplitude of the acceleration time series and the water level time series specified for each frequency according to the relationship between the amplitude of water level and acceleration. After calculating the value, a process of summing all frequencies to calculate a conversion coefficient,
a process of estimating the amplitude of the wave indicated by the water level by multiplying the acceleration time series data by a conversion coefficient that is the sum of all frequencies;
A program to run.

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