JP3393975B2 - Wave monitoring device for ship berthing - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ship berthing wave monitoring device for preventing a ship from wobbling and cutting a mooring line during seashore berthing and during berthing.

[0002]

2. Description of the Related Art A ship entering a harbor is connected to a mooring pillar on the quay by mooring lines.
When a ship is shaken by waves, an accident occurs in which the mooring line is cut. Such an accident becomes a serious problem especially in a large-sized heavy ship such as a tanker. Therefore, in order to prevent such a disconnection accident, conventionally, a wave height meter is used to monitor the size of the wave in the port, and when the wave becomes large, the number and position of mooring lines are changed, Necessary measures were taken such as changing the mooring position of the ship and activating the device when the ship was equipped with an anti-rocking device.

[0003]

However, the sway of a ship is not related only to the size of the wave, and even when the wave is small, the sway occurs, and the sway of the wave using a wave height meter is detected. The monitoring alone cannot accurately predict the occurrence of vessel sway, making it difficult to take appropriate measures.

The invention was made in order to solve such a problem, and extracts only wave components having a period that leads to the motion of the ship, predicts the motion of the ship based on the extracted wave components, An object of the present invention is to provide a wave monitoring device for berth of a ship, which can prevent the accident of cutting the mooring line and the occurrence of obstacles to mooring and cargo handling work.

[0005]

In order to achieve the above-mentioned object, the wave monitoring device for berth of a ship according to claim 1 is a wave height meter for detecting a wave in a port mooring a ship, and the wave height meter detects the wave height. It is composed of a filter that passes only a frequency signal related to the motion of the ship to be monitored from the crest signal, and a data processing device that predicts the motion of the ship based on the frequency signal extracted by the filter. .

Further, in the wave monitoring device for berth of a ship according to claim 2, the filter is constituted by a digital filter.

According to a third aspect of the seashore surfing wave monitoring device of the present invention, the filter has a bandpass characteristic that allows only a frequency signal in the vicinity of the natural vibration period of the ship to pass through.

According to a fourth aspect of the wave monitoring apparatus for docking with a ship, the filter is provided with a frequency characteristic close to the shaking characteristic of the ship.

Further, in the wave monitoring apparatus for berth of a ship according to a fifth aspect of the present invention, the data processing apparatus performs real-time processing of the frequency signal sent from the filter.

Further, in the wave monitoring device for berth of a ship according to claim 6, the data processing device is provided with an alarm generating means,
An alarm is generated when the magnitude of the frequency signal near the natural vibration cycle of the ship exceeds a set value.

Further, the ship shore shore wave monitoring device according to claim 7 has a function of automatically setting the frequency characteristic of the filter by inputting the ship condition and mooring conditions to the data processing device. It is a feature.

[0012]

The reason that a moored ship sways due to waves is that the natural vibration period of the vibration system composed of the ship and the mooring lines coincides with the wave period, resulting in a resonance state. When a ship connected by mooring lines is viewed as a vibration system, roughly speaking, the mooring line connecting the ships constitutes a spring, and the ship constitutes a weight. In such a vibration system, a natural resonance frequency determined by a spring and a weight,
That is, there is a unique vibration cycle.

Therefore, when a long-period wave having a frequency close to the natural vibration period of a ship connected by mooring lines (for example, in the case of a large tanker, one cycle is a few minutes), the ship resonates. This causes natural vibration, and the vibration gradually increases and the mooring line is cut. Therefore, whether or not the ship connected by the mooring line shakes greatly and the mooring line is disconnected depends not only on the size of the wave but also on the vibration period of the wave.

Therefore, in the wave monitoring device for berth of a ship according to claim 1, only a long-period frequency signal related to the sway of the ship is extracted by a wave height meter and a filter,
By processing this frequency signal with a data processing device, predictive data of ship sway is obtained.
By using this prediction data, it is possible to prevent accidents such as disconnection of mooring lines and obstacles to mooring and cargo handling work.

A filter can be used to extract only a long-period frequency close to the natural vibration period of the ship from the wave height signal output from the wave height meter. However, in general, the natural vibration cycle of a ship is an extremely long cycle of about several minutes as described above, and therefore L, C, R
It is quite difficult to realize such a filter having frequency characteristics that allows only a long-period frequency to pass by using an analog filter using the above.

Therefore, in the wave monitoring device for ship berth according to the second aspect, the above problem is solved by using a digital filter which can realize any filter characteristics as the filter. According to the digital filter, it is possible to reliably extract even a frequency component whose period is extremely long, which is about several minutes.

Further, in the wave monitoring apparatus for berth of a ship according to claim 3, since the filter is provided with a bandpass characteristic that allows only a frequency signal in the vicinity of the natural vibration period of the ship to pass, the data processing device. Simplifies data processing in.

Further, in the wave monitoring apparatus for berth of a ship according to claim 4, since the filter is provided with a frequency characteristic similar to the sway characteristic of the ship, the sway of the ship can be predicted more accurately. You can

Further, in the wave monitoring device for berth of a ship according to claim 5, since the data processing device processes the frequency signal sent from the filter in real time, it is possible to promptly deal with the change of the wave. it can.

Further, in the wave monitoring device for berth of a ship according to the sixth aspect, the warning is issued by the warning generating means when the magnitude of the wave near the natural vibration period of the ship exceeds a set value. Because of this, the accident of cutting the mooring line,
It is possible to reliably prevent the occurrence of obstacles to mooring and cargo handling work.

Further, in the wave monitoring device for berth of a ship according to claim 7, the data processing device has a function of automatically setting the frequency characteristic of the filter by inputting the condition of the ship and the mooring conditions. Therefore, it can be applied to any ship and any usage condition.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of a wave monitoring device for berthing a ship according to the present invention. In the figure, 1 is a wave height meter for detecting a wave state of a port where a ship is moored,
2 is a digital filter for extracting and outputting a frequency signal related to the motion of the ship to be monitored from the wave height signals detected by the wave height meter 1, and 3 is a ship using the frequency signal sent from the digital filter 2. The data processing device 4 composed of a microcomputer or the like that predicts the sway of the ship and outputs related data displays various data relating to the sway of the ship obtained by the data processing device 3 on a monitor screen and the like, and cuts the mooring line. It is a display / warning device that issues a prediction warning of.

2 (A) and 2 (B) show the vibration characteristics of the moored ship and the frequency characteristics of the digital filter 2 set correspondingly. The frequency f ₀ at which the amount of shaking in FIG. 2A peaks is the natural resonance frequency of the moored ship.
In the case of a large tanker, this natural resonance frequency f ₀ is a long-period frequency in which one period is about several minutes. This natural resonance frequency f ₀ can be calculated.

As is clear from FIG. 2 (A), when the frequency of the wave becomes high, the ship hardly sways. That is, it hardly reacts to a wave having a short cycle, but only a wave near the natural resonance frequency f ₀ . Therefore, in the digital filter 2 of FIG. 1, as shown in FIG.
The bandpass filter is configured to pass only the natural resonance frequency f ₀ and frequencies within a predetermined range before and after the natural resonance frequency f ₀ .

FIG. 3 shows a circuit example of the digital filter 2. This example is an example of a case of a so-called non-cyclic (FIR) type filter, and is an A / D converter 2
1, delay elements 22 _{1 to} 22 _j , coefficient multipliers 23 ₀ to 23
_j and an adder 24. Coefficient multiplier 2
By setting 3 ₀ ~ 23 _j each coefficient k ₀ to k _j of a predetermined value, it is possible to realize a band-pass characteristic of FIG. 2 (B).

Next, the operation of the above-mentioned wave monitoring device for docking with a ship will be described. The wave height meter 1 detects the waves in the port where the ship is moored and sends the detection signal to the digital filter 2.
The digital filter 2 passes only the natural resonance frequency f ₀ shown in FIG. 2B and frequencies within a predetermined range before and after it from the sent wave height signal and sends it to the data processing device 3.

The data processor 3 quantifies the natural resonance frequency f ₀ sent from the digital filter 2 and the crest signal in a predetermined range before and after the natural resonance frequency f _0, and predicts the shaking of the ship. For this quantification, for example, the method of obtaining the effective value,
A method of obtaining a significant wave is conceivable, but the former method is easier to calculate, so a method of obtaining this effective value will be described as an example. Note that, for example, when a meaningful wave is taken as an example of a 1/3 meaningful wave, 100 or more waves are measured, the waves are arranged in order of highest wave height, and 1/3 is taken out from the highest wave height, It is the average value of the wave height obtained from those waves. In general, since the significant wave and the effective value have a linear relationship, it is possible to obtain the value of the significant wave from the obtained effective value.

A concrete calculation of the effective value is carried out by calculating (X _i ² ) ^1/2 , where X _i is the sample value of the output waveform at the time i of the crest signal output from the digital filter 2. It can be obtained by taking a moving average of the obtained value within a range of about 20 minutes.

The natural resonance frequency f thus obtained
The effective value (average wave height) data of long-period waves near ₀ and the converted significant wave data are output to the display / alarm device 4, and the time variation of these values is displayed in a graph in real time on a monitor screen such as a CRT. indicate. In this way, it is also possible to make a temporal prediction by observing the temporal change (trend) of the effective value (average wave height) or the significant wave value in a graph.

Further, the display / warning device 4 turns on an alarm lamp and emits an alarm sound when the effective value or the value of the significant wave exceeds a certain value, thereby increasing the shaking of the ship. Notify that the mooring line may be cut. Further, when the ship is provided with the rocking preventive device, the rocking preventive device is automatically activated by this alarm signal.

The embodiment of the present invention has been described above. The ROM in the data processing device 3 stores the weight of the ship, the load amount, the number of mooring lines, the diameter, the length, the material, the positions of both ends of the mooring lines, etc. Prepare a look-up table of the filter characteristics corresponding to the ship condition and mooring conditions, and use the keyboard, etc. to check the ship weight, loading capacity, mooring line points, diameter,
By inputting the length, the material, the positions of both ends of the mooring line, etc., the coefficient multiplier 23 in the digital filter 2 is provided so as to give a filter characteristic most suitable for the input condition, as shown by the dotted line in FIG. Each coefficient k _{0 to} k of ₀ to 23 _{j
If j} is variably set, it is possible to automatically set the optimum filter characteristic for the ship situation at that time.

If an arithmetic processing program for calculating filter characteristics is prepared instead of the look-up table, the weight of the ship, the load capacity, the number of mooring lines, the diameter, the length, the material, the mooring By inputting the positions of both ends of the rope, it is possible to automatically set the optimum filter characteristics by arithmetic processing.

In the above example, the digital filter 2 has the bandpass characteristic as shown in FIG. 2B, but it may have a frequency characteristic similar to the vibration characteristic of the ship shown in FIG. 2A. It's good. In this way, when the frequency characteristic is matched with the shaking characteristic of the ship, the shaking of the ship can be predicted more accurately. In order to obtain a frequency characteristic that matches the vibration characteristic of the ship, the coefficient units 23 ₀ to 23 in FIG.
It can be realized by changing the value of _j .

Although the digital filter 2 illustrated in FIG. 3 is composed of a non-recursive (FIR) type filter, it goes without saying that it can be similarly realized by a cyclic (IIR) type filter or a digital filter using Fourier transform. is there. In the case of a digital filter using Fourier transform, the digital filter 2 outputs the filtered power spectrum of the angular frequency component. The effective value in this case can be calculated by P ^1/2, where P is the sum of all components of this power spectrum.

[0035]

As described above, according to the invention of claim 1, it is possible to predict the motion of the ship at the time of berthing and during berthing. Therefore, by using this prediction data, the mooring line It is possible to prevent accidents such as cutting accidents and obstacles to mooring and cargo handling work, thus contributing to the safety of the ship.

Further, according to the second aspect of the invention, since the filter is constituted by a digital filter, it is possible to reliably extract even a wave having a very long cycle of about several minutes, and perform accurate prediction. be able to.

According to the third aspect of the present invention, since the filter is provided with the bandpass characteristic of passing only the frequency signal in the vicinity of the natural vibration period of the ship, the data processing in the data processing device is simplified and the device is improved. Can be simplified.

Further, according to the invention of claim 4, since the filter is provided with the frequency characteristic close to the sway characteristic of the ship, the sway of the ship can be predicted more accurately, and the safety of the ship is improved. It can be improved.

According to the fifth aspect of the invention, since the data processing device processes the frequency signal sent from the filter in real time, it is possible to promptly deal with the change in waves.

Further, according to the invention of claim 6, when the magnitude of the frequency signal in the vicinity of the natural vibration period of the ship becomes equal to or larger than the set value, the alarm is issued by the alarm issuing means. It is possible to more surely prevent a rope cutting accident and an obstacle to mooring and cargo handling work.

According to the invention described in claim 7, since the data processing device is provided with a function of automatically setting the frequency characteristic of the filter by inputting the state of the ship and the mooring conditions, it It can be applied to any usage condition, and the versatility of the device can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a seashore shore wave monitoring device according to the present invention.

FIG. 2A is a shaking characteristic of a moored ship, and FIG. 2B is a frequency characteristic of a digital filter.

FIG. 3 is a diagram showing a specific circuit example of a digital filter.

[Explanation of symbols]

1 Crest meter 2 Digital filter 3 Data processing device 4 Display / warning device f ₀ Natural resonance frequency of moored ship

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Claims (7)

(57) [Claims] 1. A wave height meter for detecting waves in a port moored by a ship, and a filter for passing only a frequency signal related to the shaking of a ship to be monitored from among the wave height signals detected by the wave height meter, A wave monitoring device for ship berthing, comprising a data processing device that predicts a motion of a ship based on a frequency signal extracted by a filter. 2. The seashore shore wave monitoring device according to claim 1, wherein the filter is a digital filter. 3. The ship shore shore wave monitoring device according to claim 1, wherein the filter has a bandpass characteristic that allows only a frequency signal in the vicinity of the natural vibration period of the ship to pass therethrough. 4. The seashore shore wave monitoring device according to claim 1, wherein the filter is provided with a frequency characteristic that is similar to the vibration characteristic of the vessel. 5. The seashore shore wave monitoring device according to claim 1, wherein the data processing device processes the frequency signal sent from the filter in real time. 6. The data processing device is provided with an alarm generating means to generate an alarm when the magnitude of a frequency signal in the vicinity of the natural vibration cycle of the ship exceeds a set value. The wave monitoring device for berthing a ship according to any one of claims 1 to 5. 7. The data processing device according to claim 1, further comprising a function of automatically setting a frequency characteristic of the filter by inputting a ship condition and a mooring condition. Wave monitoring device for ship berth.