JP2022017851A - Wave measuring device - Google Patents

Abstract

To provide a wave measuring device capable of easily measuring waves while a moving object sails on the sea.SOLUTION: The wave measuring device includes: multiple draft gauges 11 to 14 that are placed at multiple positions different from each other on a water mobile to measure draft; a sway measuring gauge 15 that measures the sway of the moving object on the water; and a wave measurement unit 2 that calculates the time series data of the absolute water level fluctuation at multiple positions based on water draft data measured by the multiple draft gauges 11 to 14 and oscillation data measured by the sway measuring gauge, performs cross-spectrum analysis based on the time-series data of the absolute water level fluctuations in multiple positions, and measures wave information including at least one of wave height, wave direction or period based on the analysis results by cross-spectral analysis.SELECTED DRAWING: Figure 1

Description

The present invention relates to a wave measuring device for measuring waves.

Generally, it is required to measure waves while a ship is sailing (see Non-Patent Document 1).

Takaishi, 3 outsiders, "Study on Development of Ship-mounted Wave Information Providing System", Japan Society of Naval Architects, 2002, 2002, No. 192, p. 171-180

However, during navigation, it is not easy to measure waves due to reasons such as the hull tilting, and it is difficult to obtain measurement accuracy.

An object of the embodiment of the present invention is to provide a wave measuring device for easily measuring waves while a water moving body is navigating.

The wave measuring device according to the viewpoint of the present invention is installed at a plurality of positions different from each other of the floating body, and has a plurality of water drinking measuring means for measuring the water and a shaking measuring means for measuring the shaking of the moving body. An absolute water level fluctuation calculation means for calculating time-series data of absolute water level fluctuations at a plurality of positions based on the water water data measured by the plurality of water water measurement means and the sway data measured by the sway measurement means. At least one of wave height, wave direction or period based on the cross-spectrum analysis means for performing cross-spectrum analysis based on the time-series data of the absolute water level fluctuations at the plurality of positions and the analysis result by the cross-spectral analysis means. It is provided with a wave measuring means for measuring wave information including one.

According to the embodiment of the present invention, it is possible to provide a wave measuring device that easily measures waves while the water moving body is navigating.

The block diagram which shows the structure of the wave measuring apparatus which concerns on embodiment of this invention. The schematic diagram of the ship which shows the mounting state of the instrument which concerns on this embodiment. The flow chart which shows the procedure of the wave measurement method by the wave measurement unit which concerns on this embodiment. The waveform diagram which shows the measurement data by the instrument which concerns on this embodiment. The waveform diagram which shows the vertical acceleration data which concerns on this embodiment. The waveform diagram which shows the vertical displacement data which concerns on this embodiment. The waveform diagram which shows the absolute water level fluctuation data which concerns on this embodiment. The waveform diagram which shows the spectrum analysis data which concerns on this embodiment.

(Embodiment)
FIG. 1 is a configuration diagram showing a configuration of a wave measuring device 1 according to an embodiment of the present invention. FIG. 2 is a schematic view of the ship 10 showing the mounting state of the instruments 11 to 15 according to the present embodiment. The same parts in the drawings are designated by the same reference numerals, and duplicate description will be omitted as appropriate.

The wave measuring device 1 is installed on the ship 10 and is configured by using a computer. The ship 10 may be any water-moving body that moves on the water. For example, it may be a facility or an artificial island whose main purpose is not to move. Here, the water moving body is mainly described as a ship.

The wave measuring device 1 includes four draft meters 11, 12, 13, 14, a sway measuring meter 15, a wave measuring unit 2, and a display 3. The equipment constituting the wave measuring device 1 may also be used as a ship device or the like provided regardless of the wave measuring device 1, or may use an outboard device or equipment such as a GPS (global positioning system). You may.

The draft gauges 11, 12, 13, and 14 are mounted on the ship 10. The draft meters 11 to 14 measure the draft (height from the bottom of the ship to the water surface) at each installation position. The draft meters 11 to 14 transmit the measured draft data (draft data) to the wave measurement unit 2.

The draft meter 11 is provided on the bow portion of the ship 10. The draft meter 12 is provided on the port side of the central portion of the ship 10 in the longitudinal direction. The draft meter 13 is provided on the starboard side of the central portion of the ship 10 in the longitudinal direction. The draft meter 14 is provided at the stern portion of the ship 10. That is, the draft meters 11 and 14 are provided in the longitudinal direction (propulsion direction of the ship 10) with respect to the center O of the upper surface of the ship body (plane parallel to the water surface) of the ship 10, respectively, and the draft meters 12 and 13 are provided. , Left and right in the width direction (direction perpendicular to the propulsion direction of the ship 10) with respect to the center O, respectively.

Here, a configuration using four draft gauges 11 to 14 will be described, but any number of draft draft gauges 11 to 14 may be used as long as the number is four or more. The arrangement of the draft meters 11 to 14 is not limited to the positions described here, and any arrangement may be made as long as the draft data from the draft meters 11 to 14 are arranged at different positions.

The sway meter 15 is mounted on the ship 10. The sway measuring meter 15 measures forward / backward sway (surge), left / right sway (sway), vertical sway (heave), roll (roll), vertical sway (pitch), and bow sway (yaw). The sway measuring meter 15 transmits the measured sway data (sway data) to the wave measuring unit 2. For example, the sway data are acceleration, angular velocity and tilt angle.

The sway measuring meter 15 may be measured by any method, or may be composed of a plurality of devices. Further, if the sway measuring meter 15 measures rolling, vertical sway, and vertical acceleration, it is not necessary to measure other sway. Further, the sway measuring meter 15 may perform measurement other than the purpose used in the wave measuring device 1. For example, the data measured by the sway meter 15 may be used for the purpose of monitoring or controlling the posture of the ship 10.

The wave measuring unit 2 obtains (measures) information (wave information) related to waves based on the draft data of each installation position received from the draft meters 11 to 14 and the shaking data received from the shaking measuring meter 15. For example, wave information is wave height, wave direction and period. The wave measuring unit 2 converts the measured wave information into information for displaying on the display 3 and transmits the measured wave information to the display 3. If the wave information includes at least one of wave height, wave direction, and period, other elements may or may not be calculated.

The display 3 displays the wave information received from the wave measuring unit 2. An operator such as a sailor can grasp the wave information by looking at the display 3. The display 3 may be provided outside the ship 10. As a result, even a person outside the ship can grasp the wave information. For example, measurement data of each ship 10 navigating a major route in the world may be aggregated and analyzed to create a map displaying global wave information.

FIG. 3 is a flow chart showing a procedure of a wave measurement method by the wave measurement unit 2 according to the present embodiment.
The wave measurement unit 2 calculates the relative water level fluctuation by dividing the average draft from the draft data of each installation position measured by the draft meters 11 to 14 (step ST1).

The wave measuring unit 2 calculates the absolute water level fluctuation by correcting the calculated relative water level fluctuation based on the shaking data measured by the shaking measuring meter 15 (step ST2).

Specifically, the calculation method of the absolute water level will be described.
The vertical acceleration of the installation positions of the draft meters 11 to 14 is calculated based on the rolling angular velocity, the vertical swing angular velocity, and the vertical acceleration at the installation position of the sway measuring meter 15. The vertical acceleration of the installation position of the water gauges 11 to 14 is obtained by the following equation using the vertical acceleration of the installation position of the sway measuring meter 15, the angular acceleration of the vertical sway angle, and the angular acceleration of the horizontal sway angle.

Infinite Impulse Response (IIR) The vertical displacement is obtained by integrating the vertical acceleration twice using the following equation by the integration method using a digital filter.

As a result, the absolute water level fluctuation at the installation position of the draft gauges 11 to 14 can be obtained by subtracting the vertical displacement from the relative water level fluctuation.

The wave measurement unit 2 cross-spectral analyzes the time-series data of the absolute water level fluctuation based on the absolute water level fluctuation of the installation positions of the four draft meters 11 to 14 (step ST3). For example, the wave measurement unit 2 performs data analysis at an absolute water level having one amplitude, and doubles the result of the frequency (spectrum) analysis to convert it into an absolute wave height having both amplitudes. The wave measurement unit 2 may perform data analysis at the absolute wave height.

The wave measurement unit 2 calculates the wave height, wave direction, and period, which are wave information, based on the analysis result (step ST4).

Next, a method of analyzing the absolute water level at the installation position of the draft meters 11 to 14 and obtaining wave information will be described based on the measurement results of the draft meters 11 to 14 and the sway measuring meter 15.

Here, a cross-spectral analysis of time-series data of absolute water level fluctuation is performed using a multidimensional autoregressive model, which is one of the statistical time-series models. This estimates information about the amplitude / phase characteristics (cross spectrum) between the variables. Here, the variable is the absolute water level estimated at the installation positions of the four draft meters 11 to 14.

The cross spectrum consists of an auto component (auto power spectrum) that represents the relationship between oneself and oneself and a cross component (cross spectrum) that represents the relationship between oneself and other variables. The cross spectrum becomes a complex number. The auto component of the spectrum is a real number indicating the power (square of amplitude) at that frequency, and the imaginary part is zero. Therefore, this represents the amplitude characteristic of the variable of interest itself. On the other hand, the cross component of the spectrum indicates the strength of the correlation between the variables at that frequency. A complex number means that one vector can be written on the complex plane, so that the angle from the real axis, that is, the phase can be known. Therefore, the cross component represents the phase relationship between the variables of interest.

The wave height, wave direction and wave period are estimated as follows. Here, the cross-spectrum analysis uses a multivariate autoregressive model analysis method.
The cross spectrum of the absolute water level between the two measurement positions is obtained by the following equation using the cross-correlation function.

Using these, the phase difference of the absolute water level between the two points is calculated by the following equation.

The wave direction is calculated by the following equation using the phase difference at the dominant frequency of the sum of the power spectra of the three absolute water levels.

The representative period is calculated by the following equation. The significant wave height is obtained by averaging the power spectra of the absolute water levels at three points and multiplying the square root by four.

The frequency analysis is not limited to that described here. It may be an FFT (Fast Fourier Transform) method, a Blackman-Tukey method using a correlation function, or a Burg maximum entropy method. Here, in the method using the correlation function, it is necessary to determine the order of the model, but in the above method, the model order can be objectively determined by the information criterion.

With reference to FIGS. 4 to 8, the measurement data DG1 by the instruments including the draft meters 11 to 14 and the sway measuring meter 15 mounted on the ship 10 will be analyzed to obtain wave information.

As shown in FIG. 4, the measurement data DG1 by the instruments of the ship 10 is obtained. The horizontal axis of the waveforms W11 to W19 is time (seconds). The waveform W11 is the course (degrees), the waveform W12 is the ground speed (knot), the waveform W13 is the roll angular velocity (degrees / sec), the waveform W14 is the pitch angular velocity (degrees / sec), and the waveform W15 is the vertical acceleration (m ^ 2 / sec). ), The waveform W16 is the draft data (m) by the draft meter 11 on the bow, the waveform W17 is the draft data (m) by the draft meter 12 on the central port side, and the waveform W18 is the draft data (m) by the draft meter 13 on the central starboard side. W19 shows draft data (m) from the draft meter 14 at the stern. The course and velocity to ground are reference data and do not need to be measured.

As shown in FIG. 5, the vertical acceleration data DG2 at the installation position of the draft gauges 11 to 14 is obtained from the measurement data DG1. In the waveforms W21 to W24, the horizontal axis is time (seconds) and the vertical axis is acceleration (m ^ 2 / sec). The waveform W21 indicates the bow, the waveform W22 indicates the center port side, the waveform W23 indicates the center starboard side, and the waveform W24 indicates the acceleration data of the stern.

As shown in FIG. 6, the vertical displacement data DG3 is obtained from the vertical acceleration data DG2. In the waveforms W31 to W34, the horizontal axis is time (seconds) and the vertical axis is displacement (m). The waveform W31 indicates the bow, the waveform W32 indicates the central port side, the waveform W33 indicates the central starboard side, and the waveform W34 indicates the vertical displacement data of the stern.

As shown in FIG. 7, the absolute water level fluctuation data DG4 is obtained from the vertical displacement data DG3. In the waveforms W41 to W44, the horizontal axis is time (seconds) and the vertical axis is water level (m). The waveform W41 indicates the bow, the waveform W42 indicates the central port side, the waveform W43 indicates the central starboard side, and the waveform W44 indicates the absolute water level fluctuation data of the stern.

As shown in FIG. 8, the spectrum analysis data DG5 is obtained from the absolute water level fluctuation data DG4. In the spectrum analysis data DG5, the installation positions of the draft meters 11 to 14 of one of the two waveform data are, in order from the top, the first line is the bow, the second line is the center port side, the third line is the center starboard side, and the fourth line. The eyes indicate the stern, and the other draft draft meters 11 to 14 are installed in order from the left: the bow in the first row, the center port in the second row, the center starboard in the third row, and the stern in the fourth row. Each is shown. Therefore, the waveform located diagonally to the lower right of the analysis data DG5 represents the auto power spectrum, and the other waveforms represent the cross spectrum.

In each waveform of the spectrum analysis data DG5, the horizontal axis indicates the frequency (Hz), the vertical axis indicates the spectral density (m ^ 2 · sec), the solid line indicates the real part of the spectrum, and the broken line indicates the imaginary part of the spectrum.

The wave information estimated from the spectrum analysis data DG5 has a significant wave height of 0.66 m, a wave direction (positive clockwise from the bow) of 127.3 degrees, and an average wave period of 7.0 seconds.

According to this embodiment, wave information including wave height, wave direction, and period is obtained by cross-spectral analysis of time-series data of water level fluctuation based on the measurement results by the draft meters 11 to 14 and the sway meter 15. be able to. As a result, the seafarer can grasp the wave information while the ship 10 is sailing.

Further, since the draft meters 11 to 14 and the sway measuring meter 15 constituting the wave measuring device 1 can use existing equipment, the equipment cost of the ship 10 can be used for purposes other than the wave measuring device 1. Can be suppressed. Further, if the water moving body (ship) is provided with at least one of the draft meters 11 to 14 or the sway measuring meter 15, it is modified to mount the wave measuring device 1 by using the existing equipment. The cost can be suppressed.

The present invention is not limited to the above-described embodiment, and components may be deleted, added, or modified. Further, a new embodiment may be obtained by combining or exchanging components for a plurality of embodiments. Even if such an embodiment is directly different from the above-described embodiment, the description having the same purpose as that of the present invention is omitted as it has been described as the embodiment of the present invention.

1 ... Wave measuring device, 2 ... Wave measuring unit, 3 ... Display, 11, 12, 13, 14 ... Draft meter, 15 ... Sway measuring meter.

Claims (3)

Multiple draft measuring means that are installed at multiple different positions of the floating body to measure draft, and
A sway measuring means for measuring the sway of the moving body on the water,
An absolute water level fluctuation calculation means for calculating time-series data of absolute water level fluctuations at a plurality of positions based on the draft data measured by the plurality of draft measurement means and the sway data measured by the sway measurement means.
A cross-spectral analysis means for performing cross-spectral analysis based on the time-series data of the absolute water level fluctuations at the plurality of positions,
A wave measuring device comprising: a wave measuring means for measuring wave information including at least one of wave height, wave direction or period based on the analysis result by the cross spectrum analysis means. Claim 1 is characterized in that the plurality of positions are installed back and forth in the propulsion direction with respect to the center of the surface parallel to the water surface of the water moving body, and are provided left and right in the direction perpendicular to the propulsion direction. Wave measuring device described in. Draft is measured at multiple positions on the water moving object that are different from each other.
The shaking of the moving body on the water was measured and
Based on the draft data measured at different positions and the measured sway data, the time-series data of the absolute water level fluctuations at the plurality of positions is calculated.
Cross-spectral analysis was performed based on the time-series data of the absolute water level fluctuations at the plurality of positions.
A wave measurement method comprising measuring wave information including at least one of wave height, wave direction, and period based on the analysis result by the cross spectrum analysis.

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