Wave amplitude estimation method, amplitude estimation device, and program

Abstract

To estimate the amplitude of a wave without performing integration for acceleration time series data indicating a change over time of a measured value of the acceleration in the vertical direction applied to a floating matter floating on the water due to a vertical motion of the water surface.SOLUTION: Acceleration acquisition means 111 acquires acceleration time series data from a terminal 2 through an interface 13. Smoothing means 112 reads out the acceleration time series data acquired by the acceleration acquisition means 111 and stored in a memory 12 and smooths a change over time in a predetermined period of the acceleration indicated by the acceleration time series data. Period specification means 113 specifies, by using the acceleration time series data, a period of a change over time of the acceleration in the vertical direction applied to a floating matter J floating on the water due to a vertical motion of the water surface. Amplitude estimation means 114 estimates the amplitude of a wave according to the period specified by the period specification means 113, in accordance with the relationship between the amplitude of the wave and the period of the change over time of the acceleration.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a wave amplitude estimation method, an amplitude estimation device, and a program. [Background technology]

[0002] Wave height meters are used to monitor water level fluctuations in real time in the sea area surrounding the construction site. There are various types of wave height meters, including seabed-mounted types, airborne emission types, and buoy types.

[0003] Seafloor-mounted wave height meters are wave height meters that use ultrasonic radiation devices and water pressure sensors to detect water surface fluctuations from the seabed. Seafloor-mounted wave height meters require divers to install, making them difficult to install at great depths. In addition, because the ultrasonic radiation devices and water pressure sensors are located on the seabed, they must be connected by cable to transmit the observation data to work vessels on the ocean.

[0004] Airborne wave height meters emit ultrasonic waves from the air toward the water surface and detect water surface fluctuations from the reflected waves. However, if a workboat is moving, the movement of the wave must be taken into consideration. Also, since the wave must be emitted at a right angle toward the water surface, it is difficult to maintain the angle of ultrasonic wave emission at a right angle due to the movement of the ship.

[0005] A buoy-type wave height meter is a type of wave height meter that uses a buoy (also called a float) floating on the water surface to detect water surface fluctuations. Buoy-type wave height meter includes those that use the Global Navigation Satellite System (GNSS) and those that use an acceleration sensor.

[0006] Buoy-type wave height meters that use GNSS can obtain elevation information using GNSS, but depending on the required accuracy, the equipment can become large.

[0007] A buoy-type wave height meter using an acceleration sensor measures the vertical acceleration using an acceleration sensor attached to the buoy, and estimates water level fluctuations by double-integrating this acceleration with respect to time.

[0008] For example, Patent Document 1 describes a wave observation device that uses an acceleration sensor and is configured to obtain a velocity component by integrating the output of an acceleration sensor, or to obtain a displacement component by further integrating that velocity component.The wave observation device is characterized in that the extracted velocity component or displacement component is passed through a high-pass filter having a required passband to remove trend components that are superimposed on that component. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 61-212716 Summary of the Invention [Problem to be solved by the invention]

[0010] However, in order to estimate water level fluctuations using the method of double-integrating acceleration with respect to time, a relatively high-precision acceleration sensor is required.

[0011] One of the objects of the present invention is to estimate wave height, or wave amplitude, without integrating acceleration time series data that shows the time-dependent change in measured values ​​of vertical acceleration that floating objects on the water undergo due to the up and down movement of the water surface. [Means for solving the problem]

[0012] The amplitude estimation method according to claim 1 of the present invention is a wave amplitude estimation method comprising: an acceleration acquisition step of acquiring acceleration time series data indicating changes over time in measured values ​​of vertical acceleration that a floating object on the water experiences due to the up and down movement of the water surface; a period identification step of identifying the period of the change over time in acceleration indicated by the acceleration time series data; and an amplitude estimation step of estimating the wave amplitude corresponding to the period identified in the period identification step, in accordance with the relationship between the wave amplitude and period.

[0013] An amplitude estimation method according to claim 2 of the present invention is an amplitude estimation method in the aspect of claim 1, wherein the period identification step includes a time interval calculation step of calculating a time interval at which the acceleration that changes over time, indicated by the acceleration time-series data, changes from a negative value to a positive value, and a statistical value calculation step of calculating, as the period, a statistical value of a predetermined number of consecutive time intervals on the time axis calculated in the time interval calculation step.

[0014] An amplitude estimation method according to claim 3 of the present invention is an amplitude estimation method in the aspect of claim 1, wherein the period identification step includes a time interval calculation step of calculating a time interval at which the acceleration that changes over time, indicated by the acceleration time-series data, changes from a positive value to a negative value, and a statistical value calculation step of calculating, as the period, a statistical value of a predetermined number of consecutive time intervals on the time axis calculated in the time interval calculation step.

[0015] An amplitude estimation method according to claim 4 of the present invention is an amplitude estimation method in an embodiment according to any one of claims 1 to 3, which uses the relationship that the amplitude of a wave is the value obtained by multiplying the amplitude of the acceleration by the square of the period of the acceleration and dividing the result by four times the square of pi.

[0016] The amplitude estimation method according to claim 5 of the present invention is an amplitude estimation method in an aspect of any one of claims 1 to 4, further comprising a smoothing step of smoothing a change over time in acceleration indicated by the acceleration time-series data over a predetermined period, and wherein the period identification step identifies the period from the change over time in acceleration smoothed in the smoothing step.

[0017] The amplitude estimation device according to claim 6 of the present invention is a wave amplitude estimation device comprising: acceleration acquisition means for acquiring acceleration time series data indicating changes over time in measured values ​​of vertical acceleration that a floating object on the water experiences due to the up and down movement of the water surface; period determination means for determining the period of the change over time in acceleration indicated by the acceleration time series data; and amplitude estimation means for estimating the wave amplitude corresponding to the period determined by the period determination means in accordance with the relationship between the wave amplitude and period.

[0018] The program according to claim 7 of the present invention is a program for causing a computer to execute the following processes: acquiring acceleration time series data indicating the time-dependent change in measured values ​​of vertical acceleration that a floating object on the water experiences due to the up and down movement of the water surface; identifying the period of the time-dependent change in acceleration indicated by the acceleration time series data; and estimating the wave amplitude corresponding to the period identified in the process of identifying the period, in accordance with the relationship between the wave amplitude and period. [Effects of the Invention]

[0019] According to the present invention, it is possible to estimate wave amplitude without integrating acceleration time series data that indicates the time-dependent change in measured values ​​of vertical acceleration that floating objects on the water undergo due to the up and down movement of the water surface. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic diagram showing an example of the overall configuration of an amplitude estimation system 9. [Figure 2] FIG. 1 is a diagram showing an example of the configuration of an amplitude estimation device 1. [Figure 3] FIG. 2 is a diagram showing an example of the configuration of a terminal 2. [Figure 4] FIG. 2 is a diagram showing an example of the functional configuration of the amplitude estimation device 1. [Figure 5] FIG. 3 is a flowchart showing an example of the operation flow of the amplitude estimation device 1. [Figure 6] 5A and 5B are diagrams showing examples of time-series data acquired or calculated by the amplitude estimation device. DETAILED DESCRIPTION OF THE INVENTION

[0021] <Overall configuration of the amplitude estimation system> 1 is a schematic diagram showing an example of the overall configuration of an amplitude estimation system 9. The amplitude estimation system 9 includes an amplitude estimation device 1 and a terminal 2. The amplitude estimation system 9 shown in FIG.

[0022] The water surface Lv is the surface of the ocean or lake, and moves up and down vertically due to the action of waves. The floating object J is a structure such as a buoy that floats on the water. The floating object J moves vertically in response to the up and down movement of the water surface Lv.

[0023] The terminal 2 is attached to the floating object J. Therefore, the terminal 2, together with the floating object J, is subjected to a vertical force due to the up and down movement of the water surface Lv. The terminal 2 has a function to measure at least vertical acceleration, and generates acceleration time series data that indicates the change over time in the measured acceleration values, and supplies this to the amplitude estimation device 1.

[0024] The amplitude estimation device 1 is an information processing device, such as 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 period of the change over time in acceleration indicated by the acquired acceleration time-series data, and estimates the wave amplitude using the identified period in accordance with a predetermined relationship.

[0025] The communication line 3 is a line that wirelessly connects the amplitude estimation device 1 and the terminal 2 so that they can communicate with each other. The terminal 2 transmits the acceleration time-series data that it has generated to the amplitude estimation device 1 via this communication line 3. The communication line 3 may be, for example, a line that uses LPWA (Low Power Wide Area).

[0026] Examples of this LPWA include "ELTRES (registered trademark)", "LoRa (registered trademark)", "LoRaWAN (registered trademark)", "RPMA (registered trademark)", "SIGFOX (registered trademark)", "EnOcean (registered trademark) Long Range", "NB-IoT", "NB-Fi Protocol", "GreenOFDM", "DASH7", "Wi-SUN", "Weightless-P", "LTE-MTC", "LTE Cat.0", and "LTE Cat.M1".

[0027] <Configuration of the Amplitude Estimation Device> 2 is a diagram showing an example of the configuration of the amplitude estimation device 1. The amplitude estimation device 1 has a processor 11, a memory 12, and an interface 13. The processor 11 controls the amplitude estimation 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).

[0028] The interface 13 is an interface through which the processor 11 exchanges information with the communication line 3 and other external devices.

[0029] The processor 11 is connected to the communication line 3 via the interface 13 and acquires the acceleration time-series data generated by the terminal 2 from the communication line 3 .

[0030] The amplitude estimation device 1 is also connected to, for example, an external display device via an interface 13. The determined information is displayed to the user.

[0031] The memory 12 is a storage means such as a RAM (Random Access Memory), a ROM (Read Only Memory), a solid state drive, or a hard disk drive, and stores the operating system, various programs, data, etc. that are read into the processor 11.

[0032] <Device configuration> 3 is a diagram showing an example of the configuration of the terminal 2. The terminal 2 includes a processor 21, a memory 22, an interface 23, and an acceleration sensor 26.

[0033] The processor 21 controls the terminal 2 by executing a program stored in the memory 22. The processor 21 is, for example, a CPU.

[0034] The interface 23 is an interface through which the processor 21 exchanges information with the communication line 3 and other external devices.

[0035] The processor 21 is connected to the communication line 3 via the interface 23 and transmits the acceleration time series data to the amplitude estimation device 1 via the communication line 3 .

[0036] Furthermore, the terminal 2 may be connected to an external storage device such as a flash memory via the interface 23, and the acceleration time-series data and the like may be stored in this storage device.

[0037] The memory 22 is a storage means such as a RAM, a ROM, a solid state drive, or a hard disk drive, and stores the operating system, various programs, data, etc. that are read into the processor 21.

[0038] The acceleration sensor 26 is a sensor that measures acceleration using, for example, a MEMS (Micro Electro Mechanical Systems) system. The acceleration sensor 26 measures at least the vertical acceleration that it receives and stores the measured acceleration in sequence in the memory 22. As a result, acceleration time-series data indicating changes over time in the measured vertical acceleration is generated in the memory 22. As described above, this generated acceleration time-series data is transmitted to the amplitude estimation device 1. Note that since the terminal 2 is attached to a 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.

[0039] <Functional configuration of the amplitude estimation device> 4 is a diagram showing an example of the functional configuration of the amplitude estimation device 1. The processor 11 of the amplitude estimation device 1 executes the above-mentioned program to function as acceleration acquisition means 111, smoothing means 112, period identification means 113, amplitude estimation means 114, and reference position identification means 115.

[0040] The acceleration acquiring means 111 acquires the above-mentioned acceleration time series data from the terminal 2 via the interface 13. That is, the processor 11 functioning as this acceleration acquiring means 111 is an example of acceleration acquiring means that acquires acceleration time series data that indicates the change over time in the measured value of the vertical acceleration that a floating object on the water experiences due to the up and down movement of the water surface.

[0041] The reference position specifying means 115 shown in FIG. 4 calculates the average value of acceleration over a relatively long predetermined period (hereinafter referred to as a first period), such as a period corresponding to the most recent 100 waves (which may be non-integer waves such as 100.3 waves or 97.8 waves), based on the position that changes over time based on the acceleration time series data transmitted from the terminal 2 and acquired by the acceleration acquiring means 111, and The reference position of the water surface in the vertical direction (referred to as the reference position) is identified by using the average value of the acceleration time-series data, etc. In other words, the processor 11 functioning as this reference position identifying means 115 is an example of a processor that executes a reference position identifying step of calculating the average value of the acceleration that changes over time, which is indicated by the acceleration time-series data, for a predetermined period, and identifying the reference position of the water surface in the vertical direction based on the average value.

[0042] The smoothing means 112 reads the acceleration time-series data acquired by the acceleration acquisition means 111 and stored in the memory 12, and smooths the change over time in the acceleration indicated by this acceleration time-series data over a predetermined period. This predetermined period is a relatively short period (hereinafter referred to as the second period), for example, two seconds. In this case, the smoothing means 112 smooths the acceleration data actually measured by the terminal 2 by calculating a moving average value of the acceleration over the two seconds. Note that although the second period described above is two seconds, the second period need only be equal to or shorter than the period Ta described below, and is not limited to two seconds.

[0043] The period determination means 113 uses the acceleration time series data to determine the period of time-varying acceleration that a floating object J on the water experiences due to the up and down movement of the water surface. That is, the processor 11 functioning as the period determination means 113 is an example of a period determination means that determines the period of time-varying acceleration indicated by the acceleration time series data. The period determination means 113 shown in FIG. 4 determines the period of time-varying acceleration smoothed by the smoothing means 112.

[0044] The period identification means 113 shown in FIG. 4 includes a time interval calculation means 113a and a statistical value calculation means 113b.

[0045] The time interval calculation means 113a shown in FIG. 4 identifies the timings at which the acceleration smoothed by the smoothing means 112 undergoes a predetermined change, and calculates the time intervals between those timings.

[0046] For example, the time interval calculation means 113a uses the zero point of acceleration (average value of acceleration in the first period) corresponding to the reference position identified by the reference position identification means 115, and calculates the time interval for each wave sandwiched between two adjacent zero down crossing points where the acceleration changes from positive to negative. In other words, the processor 11 functioning as the time interval calculation means 113a is an example of a processor that executes a time interval calculation step of calculating the time interval at which the acceleration that changes over time, indicated by the acceleration time series data, changes from a positive value to a negative value.

[0047] 4 calculates statistical values ​​of a predetermined number of consecutive time intervals on the time axis calculated by the time interval calculation means 113a as the period of time change of acceleration. For example, this statistical value calculation means 113b calculates the average value of the most recent three time intervals calculated in the past as the period of time change of the current acceleration.

[0048] The amplitude estimation means 114 estimates the amplitude of the wave according to the period identified by the period identification means 113, in accordance with the relationship between the amplitude of the wave and the period of the change in acceleration over time. For example, the relationship between the amplitude of the wave and the period of the change in acceleration over time may be such that the amplitude of the wave is the value obtained by multiplying the amplitude of the acceleration by the square of the period of this acceleration and dividing the result by four times the square of pi.

[0049] The amplitude estimation means 114 transmits the estimated wave amplitude information via the interface 13 to, for example, an external display device, and displays it.

[0050] <Operation of the Amplitude Estimation Device> FIG. 5 is a flow chart showing an example of the operation flow of the amplitude estimation device 1. Processor 11 acquires acceleration time-series data (step S101) and smooths the change over time of the acceleration indicated by the acquired acceleration time-series data over a second period (e.g., 2 seconds) by calculating the arithmetic mean value of the acceleration measured over the second period (step S102).

[0051] The above-described step S101 is an example of an acceleration acquisition step for acquiring acceleration time-series data indicating the change over time in measured values ​​of vertical acceleration that a floating object on the water experiences due to the up and down movement of the water surface.

[0052] Furthermore, the above-described step S102 is an example of a smoothing step for smoothing the change over time in acceleration indicated by the acceleration time-series data over a predetermined period of time.

[0053] 6A and 6B are diagrams showing examples of time-series data acquired or calculated by the amplitude estimation device. The measured acceleration a0 shown in Fig. 6A is a curve showing the change over time in acceleration measured by the acceleration sensor 26 of the terminal 2. The horizontal axis of the graph shown in Fig. 6A represents time, and the vertical axis represents the acceleration value. Note that the measured acceleration a0 is obtained by multiplying the measured acceleration by -1, with the sign reversed.

[0054] The smoothed acceleration a shown in Fig. 6(a) ave is the arithmetic mean of the values ​​of a0 for two seconds, which is the so-called moving average. ave is the smoothed acceleration a0 measured over a predetermined period.

[0055] Meanwhile, in parallel with the execution of the process of step S102, the processor 11 executes the processes of the following steps S103 and S104 to determine a period for estimating the wave amplitude. That is, the processor 11 calculates the average value of the acceleration indicated by the acceleration time-series data acquired in step S101 over a first period (e.g., the most recent 100 waves) (step S103), and identifies the reference position of the water surface indicated by the position time-series data using this average value (step S104).

[0056] 5, the processor 11 calculates the time intervals at which the smoothed acceleration changes in a predetermined manner (step S105). The predetermined change may be, for example, the timing of the zero-down crossing point described above.

[0057] The processor 11 calculates (identifies) the statistical values ​​of a predetermined number of consecutive time intervals among the calculated time intervals as the period of the change in acceleration over time (step S106). This step S106 is an example of a period identification step of identifying the period of the change in acceleration over time indicated by the acceleration time-series data.

[0058] For example, in the graph shown in FIG. 6(a), the positive and negative signs are reversed, so that the times t0, t1, t2, t3, and t4 are all the same as the smoothed acceleration aave This is the time when the value of changes from positive to negative.

[0059] Here, period T1 is the time interval from time t0 to time t1, and period T2 is the time interval from time t1 to time t2. Furthermore, period T3 is the time interval from time t2 to time t3, and period T4 is the time interval from time t3 to time t4. Processor 11 calculates periods T1, T2, T3, and T4 at times t1, t2, t3, and t4, respectively.

[0060] That is, step S106 is performed by a peripheral device having a time interval calculation step of calculating the time interval at which the acceleration that changes over time and is indicated by the acceleration time series data changes from a positive value to a negative value. This is an example of a period specifying step.

[0061] Next, during period T4, before time t4, processor 11 calculates period Ta, which is the period of the change in acceleration over time corresponding to periods T1 to T3. Processor 11 then uses this period Ta to predict in real time the wave that will occur during period T4. Similarly, for the period after time t4, processor 11 calculates the arithmetic mean value of the most recent three periods and predicts the amplitude of the wave that will occur during the period until the next zero-down crossing point.

[0062] Although the calculation of the arithmetic mean value in the time interval step is based on the most recent three periods, it is not limited to this and may be based on one or more recent periods.

[0063] The period Ta is calculated as the arithmetic mean value of the periods T1, T2, and T3 using the periods T1, T2, and T3 as shown in the following equation (1): In other words, step S106 is an example of a period identification step that includes a statistical value calculation step that calculates, as the period of the change in acceleration over time, statistical values ​​of a predetermined number of consecutive time intervals on the time axis calculated in the time interval calculation step.

[0064] [Number 1] Ta = (T1 + T2 + T3) / 3 …(1)

[0065] Then, the processor 11 estimates the amplitude of the wave according to the calculated period Ta (step S107). est is the smoothed acceleration a of the actual displacement z. ave For example, the estimated displacement z est is the smoothed acceleration a ave is calculated by multiplying by the square of the acceleration period Ta and dividing by four times the square of pi. In this case, the estimated displacement z est is the smoothed acceleration a ave , the period Ta, and the circular constant π, as shown in the following equation (2). As mentioned above, the actual acceleration a0 is calculated in advance to reverse the sign of the measured value, so there is no negative sign in equation (2).

[0066] [Number 2] z est = (Ta 2 / 4π 2 )×a ave …(2)

[0067] Step S107 is an example of an amplitude estimation step of estimating the amplitude of the wave according to the period identified in the period identification step.

[0068] By executing the processes from step S101 to step S107 described above, the processor 11 estimates the amplitude of waves occurring on the water surface that changes over time. That is, the amplitude estimation device 1 is a device that performs a wave amplitude estimation method including the processes from step S101 to step S107 described above.

[0069] Through the above operations, the amplitude estimation device 1 calculates the period of the time-varying changes in the most recent three accelerations from the acceleration time-series data, and can estimate the time-varying changes in the water surface displacement from the time-varying changes in acceleration. In particular, high waves that threaten the safety of work at sea are known to strike in succession to a certain extent. The amplitude estimation device 1 described above can estimate the wave amplitude that contributes to work safety by taking into account the characteristics of the most recent wave.

[0070] <Modification> The above is a description of the embodiment, but the contents of this embodiment can be modified as follows: In addition, the following modifications may be combined.

[0071] <1> In the above-described embodiment, when functioning as the time interval calculation means 113a, the processor 11 identifies so-called zero-down crossing points where the acceleration changes from positive to negative, and calculates the time interval for each wave sandwiched between two adjacent zero-down crossing points, but it may also identify the timing of other changes and calculate the time interval.

[0072] For example, when functioning as the time interval calculation means 113a, the processor 11 may identify so-called zero-up crossing points where acceleration changes from negative to positive. In this case, the processor 11 may calculate the time interval for each wave between two adjacent zero-up crossing points. In this case, the processor 11 is an example of a processor that executes a time interval calculation step of calculating the time interval at which the acceleration that changes over time, indicated by the acceleration time-series data, changes from a negative value to a positive value.

[0073] <2> In the above-described embodiment, when functioning as the smoothing means 112, the processor 11 smoothes the acceleration data actually measured at the terminal 2 by calculating a moving average value of the acceleration measured over a predetermined period, such as two seconds. However, smoothing may not be performed. In this case, the period determination means 113 may simply determine the period of the change over time in the acceleration measured at the terminal 2.

[0074] <3> In the above-described embodiment, the terminal 2 has the acceleration sensor 26, but as long as the acceleration in the direction of change of the water surface Lv can be measured along the time axis, the terminal 2 does not need to have the acceleration sensor 26. Furthermore, the terminal 2 is attached to a floating object J, but the terminal 2 itself may be configured to float on the water.

[0075] <4> In the above-described embodiment, the amplitude estimation device 1 and the terminal 2 are connected to each other via the communication line 3 and exchange information, but they may exchange information without using the communication line 3. For example, the interface 13 of the amplitude estimation device 1 and the interface 23 of the terminal 2 both have a short-range wireless communication function, and the amplitude estimation device 1 and the terminal 2 may exchange information via this short-range wireless communication.

[0076] Furthermore, the amplitude estimation device 1 does not have to acquire the acceleration time series data in real time from the terminal 2. For example, the amplitude estimation 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. Furthermore, 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 estimation device 1 may acquire a copy of the acceleration time series data described above from the flash memory or the like.

[0077] <5> The program executed by the processor 11 described above may be provided in a state stored in a computer-readable recording medium, such as a magnetic recording medium such as a magnetic tape or a magnetic disk, an optical recording medium such as an optical disk, a magneto-optical recording medium, or a semiconductor memory. This program may also be downloaded via a communication line such as the Internet. That is, this program causes a computer to execute the following processes: acquiring acceleration time-series data indicating the time-dependent change in measured values ​​of vertical acceleration that a floating object on the water experiences due to the up and down movement of the water surface; identifying the period of the time-dependent change in acceleration indicated by the acceleration time-series data; and estimating the wave amplitude corresponding to the period identified in the period-identifying process, in accordance with the relationship between the wave amplitude and the period. The amplitude estimation device described above may be used as an example. As the control means, various devices other than a CPU may be used, for example, a dedicated processor. [Explanation of symbols]

[0078] 1...amplitude estimation device, 11...processor, 111...acceleration acquisition means, 112...smoothing means, 113...period determination means, 113a...time interval calculation means, 113b...statistical value calculation means, 114...amplitude estimation means, 115...reference position determination 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 object, T1 to T4...period, t0 to t4...time.

Claims

1. Acquire acceleration time series data that shows the time-dependent change in measured values ​​of vertical acceleration that floating objects receive from waves, smoothing the change in acceleration over time indicated by the acceleration time series data; Identifying a period of the smoothed acceleration change over time; Using the acceleration at a predetermined time among the smoothed time-varying acceleration and the period, an estimated value of the displacement of the floating object from a reference position at the predetermined time is calculated according to a predetermined calculation formula. method.

2. The predetermined calculation formula is: Ta is the period, a is the acceleration at the predetermined time, ave , the estimated displacement is z est When z est But, a ave This shows the relationship between the square of Ta and the value obtained by dividing by four times the square of Pi. The method of claim 1.

3. The period is the time length of a period corresponding to the most recent wave at the predetermined time indicated by the change over time of the smoothed acceleration. The method of claim 1.

4. The period is a statistical value of the time length of a period corresponding to each of a plurality of most recent consecutive waves at the predetermined time indicated by the change over time of the smoothed acceleration. The method of claim 1.

5. Acquire acceleration time series data that shows the time-dependent change in measured values ​​of vertical acceleration that floating objects receive from waves, smoothing the change in acceleration over time indicated by the acceleration time series data; Identifying a period of the smoothed acceleration change over time; Using the acceleration at a predetermined time among the smoothed time-varying acceleration and the period, an estimated value of the displacement of the floating object from a reference position at the predetermined time is calculated according to a predetermined calculation formula. Estimation device.

6. On the computer, A process of acquiring acceleration time series data showing changes over time in measured values ​​of vertical acceleration that floating objects receive due to waves; A process of smoothing the change over time in acceleration indicated by the acceleration time series data; identifying a period of the smoothed acceleration change over time; a process of calculating an estimated value of displacement of the floating object from a reference position at a predetermined time in accordance with a predetermined calculation formula using the acceleration at a predetermined time among the smoothed accelerations that change over time and the period; A program to execute.

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