阅读说明：本技术 Gm计算系统、方法和程序以及横波周期预测系统、方法和程序 (GM calculation system, method, and program, and shear wave period prediction system, method, and program ) 是由 下泽亮 堀川恭伯 津金正典 于 2019-08-23 设计创作，主要内容包括：本发明提供一种GM计算系统,其无需另行配置传感器,利用已设置的传感器的测量数据,无需复杂的数据处理即可实时高精度地计算GM。GM计算系统1中包括：船体状态量检测装置,使用被设置于船体的吃水标尺按时序检测船体状态量；横摇周期检测装置,基于由船体状态量检测装置按时序检测的船体状态量,连续地检测船体的横摇周期；典型横摇周期识别装置,基于由横摇周期检测装置检测的预定期间内的横摇周期,识别所述预定期间内船体的典型横摇周期；GM计算装置,基于由典型横摇周期识别装置识别的典型横摇周期计算船体的GM值。(The invention provides a GM calculation system which can calculate GM in real time and high precision by using the measurement data of the installed sensor without arranging a sensor additionally and without complex data processing. The GM calculation system 1 includes: a hull state quantity detection device which detects hull state quantity according to time sequence by using a draft scale arranged on a hull; a rolling period detection device that continuously detects the rolling period of the hull based on the hull state quantities detected in time series by the hull state quantity detection device; typical roll period identifying means for identifying a typical roll period of the hull in a predetermined period based on the roll period in the predetermined period detected by the roll period detecting means; and GM calculating means for calculating a GM value of the hull based on the typical roll period identified by the typical roll period identifying means.)

1. A GM calculation system for calculating a GM value for a hull, comprising:

a hull state quantity detection device which detects hull state quantity according to time sequence by using a draft scale arranged on a hull;

a rolling period detection device that continuously detects the rolling period of the hull based on the hull state quantities detected by the hull state quantity detection device in time series;

typical roll period recognition means for recognizing a typical roll period of the hull in a predetermined period based on the roll period in the predetermined period detected by the roll period detection means; and

and GM calculating means for calculating a GM value of the hull based on the typical roll period identified by the typical roll period identifying means.

2. The GM computing system of claim 1, wherein

The draft scale is arranged on the port and starboard sides of the hull,

and detecting the rolling period of the ship body according to the ship body state quantities of the left and right sides of the ship body detected by the draft scales on the port and the starboard according to time sequence.

3. The GM computing system of claim 1 or 2, wherein,

the draft scale is a quartz crystal draft scale.

4. The GM computing system of claim 3, wherein,

in the quartz crystal type draft scale, the oscillation frequency of a crystal oscillator is used as a state quantity of a ship body to detect according to time sequence.

5. A program for causing a GM calculation system that calculates a GM value of a hull to perform the steps of:

detecting a state quantity of the ship body in time sequence by using a draft scale arranged on the ship body;

continuously detecting the rolling period of the ship body based on the ship body state quantity detected according to the time sequence;

a step of identifying a typical roll period of the hull within a predetermined period based on the detected roll period within the predetermined period; and

a step of calculating the GM value of the hull based on said identified typical roll period.

6. A draft gauge provided to a hull and used in a GM computing system, the GM computing system comprising:

the ship body state quantity detection device detects the ship body state quantity according to time sequence by using the draft scale;

a rolling period detection device that continuously detects the rolling period of the hull based on the hull state quantities detected by the hull state quantity detection device in time series;

typical roll period recognition means for recognizing a typical roll period of the hull in a predetermined period based on the roll period in the predetermined period detected by the roll period detection means; and

and GM calculating means for calculating a GM value of the hull based on the typical roll period identified by the typical roll period identifying means.

7. A transverse wave period prediction system for calculating the prediction value of the transverse wave period borne by a ship body comprises:

the draft value measuring device is used for measuring the draft values of a starboard and a port of the ship body according to a time sequence;

a transverse wave period calculation device which calculates the period of the transverse wave borne by the ship body in a preset period based on time sequence data of the difference between the starboard draft value and the port draft value measured by the draft value measurement device in the preset period; and

and a predicted shear wave period calculation device that calculates a predicted value of the shear wave period based on the shear wave period calculated by the shear wave period calculation device at each predetermined time interval.

8. The shear wave cycle prediction system of claim 7,

the draught value measuring device adopts a quartz crystal type draught scale.

9. The shear wave cycle prediction system of claim 8,

in the quartz crystal draft scale, the oscillation frequency of a crystal oscillator is detected in time series as a state quantity of a ship body.

10. The shear wave cycle prediction system of any one of claims 7-9,

the predicted shear wave period calculation device uses air pressure information as an influence factor when calculating a predicted value of a shear wave.

11. A program for causing a transverse wave period prediction system that calculates a predicted value of a transverse wave period to which a hull is subjected to perform the steps of:

measuring the draught values of the starboard and the port of the ship body according to a time sequence;

calculating the period of the transverse waves borne by the ship body in a preset period based on time sequence data of the difference between the starboard draft value and the port draft value measured in the preset period; and

and calculating a predicted value of the shear wave period based on the shear wave period calculated at each predetermined time interval.

12. A draft scale provided on a hull and used in a shear wave period prediction system, the shear wave period prediction system comprising:

the draft value measuring device is used for measuring the draft values of a starboard and a port of the ship body according to a time sequence;

a transverse wave period calculation device that calculates a period of a transverse wave to which the hull is subjected during a predetermined period, based on time series data of a difference between a starboard draft value and a port draft value measured by the draft value measurement device during the predetermined period; and

and a predicted shear wave period calculation device that calculates a predicted value of the shear wave period based on the shear wave period calculated by the shear wave period calculation device at each predetermined time interval.

Technical Field

The invention relates to a GM calculation system, a GM calculation method, a GM calculation program, a shear wave period prediction system, a shear wave period prediction method, and a shear wave period prediction program.

Background

In the marine field (ship shipping), it is important to accurately grasp hull state data, that is, data relating to the motion of a hull such as acceleration and displacement of the hull, and hull state data, that is, data relating to the state of the hull such as draft and GM of the hull, from the viewpoint of safety measures, for a ship that is sailing on irregularly changing waves.

In particular, the accurate real-time grasp of the GM of the hull is the most important problem from the viewpoint of preventing the hull from overturning. The GM of the hull is defined as a distance between the centroid M and the center of gravity G of the hull, and is a value that changes at every moment based on the inclination of the hull. Wherein, the center of stability M is a point where the direction of the buoyancy with the center of buoyancy as the action point intersects with a line passing through the vertical direction of the center of gravity on the cross section of the ship when the ship body is transversely inclined. If the GM is estimated erroneously, not only is safe navigation impossible, but in the worst case, there is a risk of overturning.

On the other hand, it is necessary to consider the influence of a composite wave of waves from various directions, in addition to the waves from the lateral direction, which influence the GM. Therefore, conventionally, in order to accurately grasp or predict the GM, it is necessary to manually input the incident angle in order to grasp the incident direction of the waves on the hull. However, in situations where the hull is likely to be overturned by a large wave, it is impractical to manually input the angle of incidence of the wave.

Therefore, in recent years, GM is estimated using an approximation equation and a model (patent document 1).

It is generally considered that the period of the wave is about 30 seconds to 300 seconds, and the height (peak value) of the wave increases as the period becomes longer. That is, by predicting the period of the transverse wave, the height of the wave received by the hull can be predicted.

In recent years, the height of waves is predicted by analyzing the temporal change in physical quantities measured by sensors provided on the hull (patent document 2).

Disclosure of Invention

Problems to be solved by the invention

According to the invention described in patent document 1, the GM is calculated using a second-order linear probabilistic mechanical model or a general state space model based on time series data of roll angle measured by a GPS compass or a gyro sensor. Based on such a technique, a separately configured sensor such as a GPS compass or a gyro sensor is required, and it is difficult to detect an accurate roll angle. Further, the estimation method uses a plurality of models, data processing becomes complicated, and GM cannot be estimated with high accuracy. Therefore, misreading the actual GM value may, in the worst case, hinder security.

In addition, according to the invention described in patent document 2, the direction or height of the wave is predicted based on the change over time of the liquid level height measured by the microwave water level sensor including the modules provided at four positions of the hull and the change in the hull motion measured by the accelerometer or gyro sensor. Based on such technology, an additionally configured sensor such as a microwave water level sensor, an accelerometer, or a gyro sensor is required. Further, since not only the transverse wave but also the behavior of the composite component of the waves incident from each direction is predicted, it is necessary to analyze the measurement values of a total of eight sensors provided at four positions of the hull, and there is a problem that data processing becomes complicated and a high-performance computer for smoothly performing the data processing is required.

In view of the above problems, it is an object of the present invention to provide a system that can calculate a GM in real time with high accuracy using measurement data of an existing sensor without disposing a separate sensor and without complicated data processing.

Another object of the present invention is to provide a system for predicting the period of a transverse wave received by a ship body during navigation with high accuracy, without requiring a separate sensor, and using measurement data of an existing sensor, without requiring complicated data processing.

Means for solving the problems

The present invention provides the following solution.

The invention of feature 1 provides a GM computing system comprising: a hull state quantity detection device which detects hull state quantity according to time sequence by using a draft scale arranged on a hull; a rolling period detection device that continuously detects the rolling period of the hull based on the hull state quantities detected by the hull state quantity detection device in time series; typical roll period recognition means for recognizing a typical roll period of the hull in a predetermined period based on the roll period in the predetermined period detected by the roll period detection means; and GM calculating means for calculating a GM value of the hull based on the typical roll period identified by the typical roll period identifying means.

According to the invention of the first aspect, since the GM value can be calculated by using the draft scale provided on the hull, the GM value can be calculated in real time with high accuracy without providing a separate sensor and without requiring complicated data processing.

In the invention according to claim 2, in the invention according to claim 1, the draft scale is provided on the port and starboard sides of the hull, and the roll period of the hull is detected from the hull state quantities on the port and starboard sides of the hull detected in time series by the draft scale.

According to the invention of the second aspect, since the roll period of the hull is detected using the draft gauges provided on the port and starboard sides of the hull, an accurate GM value can be calculated without knowing the incident angle of the wave with respect to the hull and without inputting the incident angle of the wave by a crew.

With regard to the invention according to feature 3, in addition to the invention according to feature 1 or 2, the draft scale is a quartz crystal draft scale.

According to the invention of the third feature, since the draft scale of quartz crystal type is used as the draft scale for detecting the state quantity of the hull, unlike the draft scales of other forms, digital measurement is possible without generating a conversion error accompanying a/D conversion, and the GM value can be calculated with higher accuracy.

The invention according to claim 4 is the invention according to claim 3, wherein the quartz crystal draft scale is configured to detect the oscillation frequency of the crystal oscillator in time series as the hull state quantity.

According to the invention of the feature 4, since the oscillation frequency of the crystal oscillator in the quartz crystal draft scale is used as the hull state quantity and the change in the oscillation frequency is used as the roll period, direct and continuous measurement is possible. Therefore, a highly accurate GM calculation system can be constructed with a small amount of data processing without intentionally converting specific other physical quantities.

The invention of the 5 th feature provides a shear wave period prediction system including: the draft value measuring device is used for measuring the draft values of a starboard and a port of the ship body according to a time sequence; a transverse wave period calculation device which calculates the period of the transverse wave borne by the ship body in a preset period based on time sequence data of the difference between the starboard draft value and the port draft value measured by the draft value measurement device in the preset period; and a predicted shear wave period calculation device that calculates a predicted value of the shear wave period based on the shear wave period calculated by the shear wave period calculation device at each predetermined time interval.

According to the invention of the 5 th aspect, since the transverse wave period can be predicted by the draft gauge provided on the hull, the transverse wave period to which the hull is subjected during the travel can be predicted with high accuracy without providing a separate sensor and without requiring complicated data processing. In addition, when calculating the period of the transverse wave, since only the time series data of the difference between the starboard draft value and the port draft value is used, the period of the transverse wave can be accurately grasped without considering the incident angle of the wave or the synthesis of the wave.

With regard to the invention of the 6 th feature, on the basis of the invention of the 5 th feature, the draft value measuring device employs a quartz crystal draft scale.

According to the invention of the feature 6, since the draft scale of the quartz crystal type is used as the draft scale for detecting the state quantity of the hull, unlike the draft scales of other types, digital measurement is possible without generating a conversion error accompanying a/D conversion, and the period of the transverse wave can be predicted with higher accuracy.

The invention according to claim 7 is the invention according to claim 2, wherein the quartz crystal draft scale is configured to detect an oscillation frequency of the crystal oscillator in time series as the hull state quantity.

According to the invention of the feature 7, since the oscillation frequency of the crystal oscillator in the quartz crystal draft scale is used as the hull state quantity and the change in the oscillation frequency is used as the roll period, direct and continuous measurement is possible. Therefore, a high-precision transverse wave period prediction system can be constructed by a small amount of data processing without specially converting specific other physical quantities.

The invention according to the 8 th aspect is the invention according to any one of the 5 th to 7 th aspects, wherein the predicted shear wave period calculation device uses air pressure information as an influence factor in calculating the predicted value of the shear wave.

According to the invention of the 8 th aspect, since the air pressure information is used as the influence factor in the calculation, the predicted value of the shear wave period can be calculated with higher accuracy.

Effects of the invention

The present invention can provide a system that can calculate a GM in real time and with high accuracy by using measurement data of an existing sensor without additionally providing a sensor and without complicated data processing.

The present invention can also provide a system that can predict the shear wave period with high accuracy without complicated data processing by using measurement data of an existing sensor without additionally providing a sensor.

Drawings

Fig. 1 is a block diagram showing a hardware configuration and software functions of a GM computing system 1 according to embodiment 1 of the present invention.

Fig. 2 is a diagram showing an example of arrangement of a draft scale in a hull.

Fig. 3 is a flowchart showing a GM calculation method in embodiment 1.

Fig. 4 shows an example of the hull state quantity database 31.

Fig. 5 is a block diagram showing a hardware configuration and software functions of the transverse wave period prediction system 101 according to embodiment 2 of the present invention.

Fig. 6 is a diagram showing an example of arrangement of a draft scale in a hull.

Fig. 7 is a flowchart showing a method of predicting a period of a transverse wave in the present embodiment.

Fig. 8 shows an example of the hull state quantity database 131.

Fig. 9 is a flowchart showing a GM calculation method in embodiment 2.

Detailed Description

< embodiment 1 >

Hereinafter, embodiment 1 for carrying out the present invention will be described with reference to the drawings. This is merely an example, and the technical scope of the present invention is not limited thereto.

[ Structure of GM calculation System 1 ]

Fig. 1 is a block diagram illustrating a hardware configuration and software functions of the GM computing system 1 according to the present embodiment.

The GM calculation system 1 includes: a control unit 10 for controlling data, a communication unit 20 for communicating with a user and other devices, a storage unit 30 for storing data, an input unit 40 for receiving information input from the user, a display unit 50 for outputting data and images controlled by the control unit 10, and a measurement unit 60 for measuring data.

The control unit 10 includes: CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), etc.

The communication section 20 includes a device usable for communication with other apparatuses, for example, a Wi-Fi (Wireless Fidelity) counterpart device based on IEEE 802.11.

The control unit 10 reads a predetermined program and, by cooperating with the communication unit 20 and/or the measurement unit 60 as necessary, realizes the hull state quantity detection module 11, the roll period detection module 12, the typical roll period recognition module 13, and the GM calculation module 14.

The storage unit 30 is a storage device for data and files, and includes a storage unit for data such as a hard disk, a semiconductor memory, a recording medium, and a memory card. The storage unit 30 stores a hull state quantity database 31 described later.

The type of the input unit 40 is not particularly limited. The input unit 40 may be a keyboard, a mouse, a touch panel, or the like.

The type of the display unit 50 is not particularly limited. Examples of the display unit 50 include a display and a touch panel.

In the present embodiment, the measuring section 60 is constituted by draft scales D1 to D2 for measuring a draft value defined as a vertical distance from the water surface to the bottom of the hull. As shown in fig. 2, the draft scale is composed of four components: draft scale D1 provided near the center of the bow of the hull, draft scales D2 and D3 provided on the left and right sides near the center of the hull, and draft scale D4 provided near the stern of the hull.

[ structures of draft scales D1-D4 ]

As draft scales D1 to D4 constituting the GM calculation system 1 according to the present embodiment, quartz crystal draft scales were used. The operation principle of the quartz crystal draft scale will be explained below.

The draft scale of quartz crystal type uses a crystal oscillator as a detection element. Since the crystal oscillator has a property that the oscillation frequency changes in proportion to the applied pressure, the frequency of the quartz crystal draft scale is directly measured by a counter, and the pressure (water pressure) applied to the detection element can be grasped, so that the water depth of the setting position of the detection element can be detected, and the draft value can be calculated.

In the draft scale using a crystal oscillator, since the oscillation frequency of the quartz crystal is directly measured by a counter, digital measurement is possible, and unlike a conventional draft scale such as a semiconductor draft scale in which pressure needs to be measured in the form of an analog signal and a/D conversion is performed, high-precision draft value detection without a conversion error can be realized.

That is, if another form of draft scale such as a semiconductor draft scale is used, the pressure at the draft scale set position is measured in an analog manner. When data processing such as fourier analysis is performed on the pressure measured in time series, it is necessary to convert the measured pressure value from an analog type to a digital signal (a/D conversion). In this case, since an error occurs when the analog signal is converted into the digital signal, the measurement error of the semiconductor draft scale is about 10 times as large as that of the quartz crystal draft scale in the present embodiment.

In the present embodiment, since the quartz crystal draft scale is used, the oscillation frequency of the crystal oscillator can be measured by the counter in the form of a digital signal. Therefore, the measured data does not need to be digitally converted, and the GM value can be calculated with high accuracy without generating a conversion error of the a/D conversion.

[ flow of GM calculation method Using GM calculation System 1 ]

Fig. 3 is a flowchart showing a GM calculation method using the GM calculation system 1. Fig. 4 is a diagram showing an example of the hull state quantity database 31. The processing executed by the hardware and software modules will be described with reference to fig. 2 to 4. In the present embodiment, the GM value of the hull is repeatedly calculated by repeatedly executing the control logic of step S10 to step S50.

[ step S10: detection of State quantity of hull ]

First, when the system is started, the control unit 10 of the GM calculation system 1 executes the hull state quantity detection module 11 in cooperation with the measurement unit 60 to detect the hull state quantity in time series (step S10). In step S10, the hull state quantity is detected at predetermined time intervals for a predetermined period of time based on a draft scale provided on the hull. The predetermined time interval may be set as appropriate, for example, 1 second interval or 1/10 second interval.

In the present embodiment, the oscillation frequency of the quartz crystal is detected as time series data on the basis of draft scales D2 and D3 provided on the port and starboard sides.

[ step S20: detection of roll period of hull ]

Next, the control section 10 of the GM calculation system 1 executes the roll period detection module 12 to continuously detect the roll period of the hull, which is defined as the time interval of the maximum roll of the port and starboard (step S20).

In the present embodiment, the roll period of the hull is detected based on the time series data of the oscillation frequency detected by draft scales D2 and D3 provided on the port and starboard sides. Since the detected oscillation frequency is a state quantity corresponding to the pressure applied to the crystal oscillator, the change in oscillation frequency with time indicates the change in pressure with time. Since the above-described changes indicate the rolling of the hull, the waveform period of the time series data indicating the oscillation frequency on the draft scales D2 and D3 corresponds to the rolling period of the hull. In the present embodiment, the peak of the maximum value and the peak of the minimum value of the oscillation frequency are detected from the waveform of the time series data indicating the oscillation frequency, and the roll period is detected from the time between the peaks.

In the present embodiment, the oscillation frequency of the quartz crystal is measured using the quartz crystal draft scale and the roll period of the hull is detected using the oscillation frequency, but the present invention is not limited thereto, and other hull state quantities may be used as long as the roll period can be detected. For example, the roll period may also be detected from the change in draught values for port and starboard over time. Alternatively, the roll period may be detected from a change in the inclination or the roll amount with time.

In the present embodiment, the peak is detected from the waveform of the time series data indicating the hull state quantity, and the roll period is detected from the time between the peaks, but the present invention is not limited to this, and the period may be detected by performing spectrum analysis on the waveform, or the period may be detected using a conventional statistical model indicating the roll timing.

[ step S30: storage of roll period of hull ]

When the roll period of the hull is detected in step S20, the detected roll period is stored in the hull state quantity database 31 (step S30). The roll period is continuously detected, and the detected roll period value is stored in the hull state quantity database 31 together with the detected time as shown in fig. 4.

[ step S40: identification of typical roll periods ]

Next, the control unit 10 executes the typical roll period recognition module 13 in cooperation with the storage unit 30, extracts a roll period of a predetermined period stored in the hull state amount database 31, and recognizes a typical period of a roll period within the predetermined period using the extracted roll period (step S40).

Here, the predetermined period means, for example, a period of 20 minutes elapsed from the current time, and in this case, a typical period of the predetermined period means a typical value of a roll period within 20 minutes. As described above, in step S30, the roll period is stored together with the time. Then, all the roll periods detected between the times up to a predetermined time (here, 20 minutes) from the current time are extracted, and a typical period of the roll period within the predetermined period is identified by fourier analysis of the extracted roll period data.

The typical cycle identification in step S40 is performed every predetermined time, for example, every 2 seconds.

[ step S50: calculation of GM value ]

Next, the control unit 10 executes the GM calculation module 14, and calculates the GM value by the formula (1) using the typical period of the roll period of the hull identified in step S40. The calculated GM value is displayed on the display unit 50 in real time.

GM＝(0.8B/Tγ’)²The type (1)

Here, in equation (1), B is the beam width (m) of the hull, and T γ' is a typical period (sec) of the roll period identified by fourier analysis in step S40.

The calculation of the GM value in step S50 is performed at predetermined time intervals, for example, every 2 seconds, and the latest value is displayed on the display unit 50 each time the calculation is performed. The crew can continue safe navigation by checking the GM value displayed one by one on the display unit 50 and performing various controls on the hull.

In addition, when calculating the GM value and calculating it more strictly, equation (2) with the radius of gyration obtained in the center of gravity inspection (tilt test) at the time of new construction can be used.

GM＝(2.01K/T)²The type (2)

Here, in equation (2), K is the turning radius (m) of the hull, and T is the natural period (sec) of the hull that varies based on the draft value.

When the turning radius k (m) of the hull can be obtained, the GM value can be calculated by the equation (2). However, when the formula (1) is used, the accuracy may be the same as that when the GM value is calculated by the formula (2).

In this way, the GM value is calculated from the time series data of the hull state quantities detected by the draft scale provided on the hull and the typical period of the roll period identified by fourier analysis, and the GM value can be calculated in real time with high accuracy without requiring complicated data processing. In addition, since the draft scale for detecting the state quantity of the hull is already provided to the hull, it is not necessary to provide a new sensor or the like for calculating the GM value, and a low-cost and high-accuracy GM calculation system can be constructed.

Further, since the roll period, which is the time interval of the maximum roll of the port and starboard sides, is detected using the time series data of the hull state quantities detected by the draft gauges installed on the port and starboard sides of the hull, the GM calculation system can be constructed at a low cost and with high accuracy by using existing facilities without requiring special measuring facilities and high-performance calculation facilities.

In addition, the quartz crystal draft scale is adopted as the draft scale for detecting the state quantity of the ship body, and the state quantity of the ship body can be measured in a digital signal mode unlike the draft scales in other modes. Therefore, a GM calculation system with high precision and no conversion error can be constructed without A/D conversion during data processing.

Further, since the oscillation frequency of the crystal oscillator in the quartz crystal draft scale provided on the left and right sides of the hull is used as the hull state quantity to be detected, the change in the oscillation frequency is used as the roll period, and direct and continuous measurement can be performed. Therefore, a highly accurate GM calculation system with a small amount of data processing can be constructed without intentionally converting specific other physical quantities.

[ measurement of draft value of hull ]

A method of measuring the draft value of a ship body using draft scales D1 to D4 constituting the GM calculation system 1 of the present embodiment will be described.

The oscillation frequency detected by draft scales D2 and D3 was used for calculating the GM value. When measuring the draft value, the oscillation frequency is converted into pressure (water pressure), thereby calculating the water depth of the installation position of the detection element, and the draft value of the ship body is derived by using the water depth and the distance from the installation position of the detection element to the ship bottom.

As shown in fig. 2, since the draft scale D1 of the bow is disposed at a position shifted from the bow line, the measurement value measured by the draft scale D1 is converted to the bow line position, which is the bow draft value.

Furthermore, since the draft scales D2 and D3 are provided at the left and right positions near the center of the hull at positions shifted from the center line of the hull, the measured values measured by the draft scales D2 and D3 are converted to the center line of the hull, which is the left and right draft values of the center of the hull.

Since the draft scale D4 at the stern portion is disposed at a position offset from the stern line, the measured value measured by the draft scale D4 is converted to the stern line position, i.e., the stern draft value.

The draft value obtained as described above is subjected to temperature correction using the water temperatures measured by the thermometers attached to the draft gauges D1 to D4 and hull inclination correction (trim: forward and backward inclination, list: lateral inclination) based on the automatic calculation function, thereby obtaining a corrected draft value.

Further, since the seawater specific gravity of the estuary is different from that of the ordinary saltwater waters, and freshwater waters, the seawater specific gravity of the estuary is corrected by manually inputting a measurement value. Standard seawater specific gravity is adopted in the shipping state.

The measurement of the draft value of the hull is carried out as described above.

[ recognition of the period of the meeting of the bow of the hull with waves ]

In the present embodiment, a method of recognizing the meeting period of the hull bow and the wave using draft scale D1 or D4 constituting the GM calculation system 1 will be described.

First, the pitch period of the bow or stern is measured using draft scales D1 or D4. That is, as in the calculation of the GM value, the sway of the hull can be detected from the change in the oscillation frequency of the crystal oscillator in the draft scale, and the period of the sway can be detected from the period of the change in the oscillation frequency.

Then, the time interval of the maximum pitching of the bow or stern is continuously detected by the change of the oscillation frequency of the draft scale D1 or D4 provided at the bow or stern, and the detected continuous pitching period data is fourier analyzed, thereby identifying the typical period of the pitching period thereof.

[ calculation of deflection in the fore-and-aft direction of the hull ]

In the present embodiment, a method of calculating the fore-and-aft direction deflection of the hull using draft scales D1 or D4 constituting the GM calculation system 1 will be described.

The fore-and-aft direction deflection of the hull, defined as the difference between the average of the bow draft value and the stern draft value and the hull center draft value, is a value that briefly indicates whether the hull is in a mid-camber state (convex state) or a mid-sag state (concave state) in the fore-and-aft direction. In calculating this value, for each measured value, a time average of the draft values over a predetermined period (e.g., 150 seconds) is taken.

Then, the arithmetic mean value of the hull central draft is subtracted from the arithmetic mean value of the bow draft and the stern draft to calculate the value of the deflection. The value is an important index of the bending moment of the ship body and the weight of loaded goods, which are closely related to the strength of the ship body, and the value can be accurately grasped to prevent major accidents.

< embodiment 2 >

Hereinafter, embodiment 2 for carrying out the present invention will be described with reference to the drawings. This is merely an example, and the technical scope of the present invention is not limited thereto.

[ Structure of transverse wave period prediction System 101 ]

Fig. 5 is a block diagram illustrating a hardware configuration and software functions of the transverse wave period prediction system 101 according to the present embodiment.

The shear wave period prediction system 101 includes: a control unit 110 for controlling data, a communication unit 120 for communicating with a user and other devices, a storage unit 130 for storing data, an input unit 140 for receiving information input from the user, a display unit 150 for outputting data and images controlled by the control unit 110, and a measurement unit 160 for measuring data.

The control section 110 includes: CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), etc.

The communication section 120 includes a device usable for communication with other apparatuses, for example, a Wi-Fi (Wireless Fidelity) counterpart device based on IEEE 802.11.

The control unit 110 reads a predetermined program, and cooperates with the communication unit 120 and/or the measurement unit 160 as necessary to realize the hull state quantity detection module 111, the draft value calculation module 112, the roll period calculation module 113, the predicted roll period calculation module 114, the roll period detection module 115, the typical roll period recognition module 116, and the GM calculation module 117.

The storage unit 130 is a storage device for data and files, and includes a storage unit for data such as a hard disk, a semiconductor memory, a recording medium, and a memory card. The storage unit 130 stores a hull state quantity database 131 described later.

The type of the input unit 140 is not particularly limited. The input unit 140 may be a keyboard, a mouse, a touch panel, or the like.

The type of the display unit 150 is not particularly limited. The display unit 150 may be a display, a touch panel, or the like.

In the present embodiment, the measurement section 160 is constituted by draft scales D101 to D104 for measuring a draft value defined as a vertical distance from the water surface to the bottom of the hull. As shown in fig. 6, the draft scale is composed of four components: draft scale D101 provided near the center of the bow of the hull, draft scales D102 and D103 provided on the left and right sides near the center of the hull, and draft scale D104 provided near the stern of the hull.

[ structures of draft scales D101 to D104 ]

As draft scales D101 to D104 constituting the transverse wave period prediction system 1 of the present embodiment, quartz crystal draft scales are used. The operation principle of the quartz crystal draft scale will be explained below.

The draft scale of quartz crystal type uses a crystal oscillator as a detection element. Since the crystal oscillator has a property that the oscillation frequency changes in proportion to the applied pressure, the frequency of the quartz crystal draft scale is directly measured by a counter, and the pressure (water pressure) applied to the detection element can be grasped, so that the water depth of the setting position of the detection element can be detected, and the draft value can be calculated.

In the draft scale using a crystal oscillator, since the oscillation frequency of the quartz crystal is directly measured by a counter, digital measurement is possible, and unlike a conventional draft scale such as a semiconductor draft scale in which pressure needs to be measured in the form of an analog signal and a/D conversion is performed, high-precision draft value detection without a conversion error can be realized.

That is, if another form of draft scale such as a semiconductor draft scale is used, the pressure at the draft scale set position is measured in an analog manner. When data processing such as fourier analysis is performed on the pressure measured in time series, it is necessary to convert the measured pressure value from an analog type to a digital signal (a/D conversion). In this case, since an error occurs when the analog signal is converted into the digital signal, the measurement error of the semiconductor draft scale is about 10 times as large as that of the quartz crystal draft scale in the present embodiment.

In the present embodiment, since the quartz crystal draft scale is used, the oscillation frequency of the crystal oscillator can be measured by the counter in the form of a digital signal. Therefore, the measured data does not need to be digitally converted, and the GM value can be calculated with high accuracy without generating a conversion error of the a/D conversion.

Draft scales D102 and D103 provided on the port and starboard sides are preferably provided at the port and starboard side ends, respectively. Since draft scales are provided at the ends of the starboard and port sides, a system with a small measurement error can be constructed.

[ procedure of transverse wave period prediction method Using transverse wave period prediction System 1 ]

Fig. 7 is a flowchart showing a method of predicting a shear wave period using the shear wave prediction system 101. Fig. 8 is a diagram showing an example of the hull state quantity database 131. The processing executed by the hardware and software modules will be described with reference to fig. 6 to 8. In the present embodiment, the control logic of steps S110 to S160 is repeatedly executed, thereby repeatedly calculating the predicted value of the transverse wave period of the hull.

[ step S110: detection of State quantity of hull ]

First, when the system is started, the control unit 110 of the transverse wave cycle prediction system 101 cooperates with the measurement unit 160 to execute the hull state quantity detection module 111 and detect the hull state quantities in time series (step S110). In step S110, the hull state quantity is detected at predetermined time intervals for a predetermined period based on a draft scale provided on the hull. The predetermined time interval may be set as appropriate, for example, 1/2-second intervals or 1/10-second intervals.

In the present embodiment, the oscillation frequency of the quartz crystal is detected as time series data based on draft scales D102 and D103 provided on the port and starboard sides.

[ step 120: calculation of draft values on port and starboard sides of hull ]

Next, the control unit 110 of the transverse wave period prediction system 101 executes the draft value calculation module 112 to measure the draft values of the starboard and port sides of the hull in time series using the quartz crystal draft scales D102 and D103 provided on the port and starboard sides of the hull (step 120). When draft values are measured using quartz crystal draft gauges D102 and D103 installed on the port and starboard sides of the hull, the oscillation frequency detected as the state quantity of the hull is converted into pressure (water pressure) in step 110, thereby calculating the water depth of the installation position of the detection element, and the draft value of the hull is calculated using the water depth and the distance from the installation position of the detection element to the bottom of the ship.

Since the draft scales D102 and D103 at the left and right positions near the center of the hull are both provided at positions shifted from the center line of the hull, the measured values measured by the draft scales D102 and D103 are converted to the center line of the hull, which is the left and right draft values of the center of the hull.

The draft value obtained as described above is subjected to temperature correction using the water temperature measured by the thermometer attached to each draft scale D102, D103 and hull inclination correction (trim: forward and backward inclination, list: lateral inclination) based on an automatic calculation function, thereby obtaining a corrected draft value.

Further, since the seawater specific gravity of the estuary is different from that of the ordinary saltwater waters, and freshwater waters, the seawater specific gravity of the estuary is corrected by manually inputting a measurement value. Standard seawater specific gravity is adopted in the shipping state.

[ step 130: storage of draft values on port and starboard sides of hull ]

When the draft values of the port and starboard sides of the hull are calculated in step 120, the calculated draft values are stored in the hull state quantity database 131 (step 130). For example, the detection of the state quantity of the hull and the calculation of the draft value are continuously performed every 1/2 seconds. As shown in fig. 8, the calculated draft values for port and starboard sides are stored in the hull state quantity database 131 as time series data together with the time at which the corresponding hull state quantity is detected.

[ step 140: calculation of the period of the transverse waves to which the hull is subjected ]

Next, the control unit 110 of the transverse wave cycle prediction system 101 executes the transverse wave cycle calculation module 113 to calculate the cycle of the transverse wave received by the hull for a predetermined period (step 140). Here, the predetermined period is, for example, a period in which 20 minutes have elapsed from the current time.

The transverse wave period is calculated from the time series data of the difference between the draft value measured by draft scale D102 provided on one side of the hull and the draft value measured by draft scale D103 provided on the other side of the hull.

That is, in steps 110 and 120, the draft values of the starboard and port of the hull are calculated as time series data on the draft scales D102 and D103, and the calculated draft values of the starboard and port are stored in the hull state quantity database 131 together with the time in step 130.

Then, in step 140, the difference between the starboard draft value and the port draft value at each time stored in the hull state quantity database 131 in step 130 is extracted, and the difference is extracted in time series together with the detection time. At this time, the time-series data of the difference in draft values takes values that change so as to draw a waveform based on the magnitude and cycle of the transverse wave received by the hull. Then, fourier analysis is performed on the difference of the draft values extracted during a predetermined period (for example, 20 minutes elapsed from the current time), and the period of the cross wave during the predetermined period is calculated.

The above calculation of the shear wave period is performed at every predetermined time interval (for example, every 4 minutes). In this way, a typical shear wave period in 20 minutes past the current time can be calculated every 4 minutes.

In the present embodiment, the period of the transverse waves to which the hull is subjected is detected as the change over time in the difference between the port and starboard draft values, but the present invention is not limited to this, and other hull state quantities may be used as long as the rolling period can be detected. For example, the transverse wave period may be detected using the oscillation frequency of the quartz crystal measured by the quartz crystal draft scale.

That is, the oscillation frequency detected by the quartz crystal draft scale is a state quantity corresponding to the pressure applied to the crystal oscillator, and the change in oscillation frequency with time indicates the change in pressure with time. Since the above-described change indicates the sway of the hull, the waveform period of the time series data indicating the oscillation frequency of the draft scales D102 and D103 corresponds to the roll period of the hull. Therefore, the maximum value and the minimum value of the oscillation frequency are detected from the waveform of the time series data indicating the oscillation frequency, and the roll period is detected from the time between the peaks.

In addition, the roll period can also be detected from the change of the inclination or the roll amount of the hull with time.

In the present embodiment, the change over time in the difference between the port and starboard draft values over a predetermined period is fourier analyzed to calculate the shear wave period, but the present invention is not limited to this, and peaks may be detected from time series data indicating the hull state quantity, and the period may be detected from the time between the peaks, or a conventional statistical model detection period indicating the time series of the rolling motion may be used.

[ step 150: storage of transverse wave period to which the hull is subjected ]

When the ship hull-borne shear wave period is calculated in step 140, the calculated shear wave period is stored in the ship hull state quantity database 131 (step 150). The calculation of the shear wave period is performed at predetermined intervals (for example, at intervals of 4 minutes), and the value of the calculated shear wave period is stored as time series data in the hull state quantity database 131 together with the calculation time as shown in fig. 8.

[ step 160: calculation of predicted period of transverse wave ]

Next, the control unit 110 executes the predicted transverse wave period calculation module 114 in cooperation with the storage unit 130, extracts the transverse wave period within the predetermined period stored in the hull state quantity database 131, and calculates a predicted value of the transverse wave period at a time after the predetermined period using the extracted transverse wave period (step 160).

As described above, in step 150, the shear wave period during a period from a certain time onward by a predetermined time is stored together with the time. All the shear wave cycles (in this case, 5) calculated between the current time and the time after a predetermined time (here, 20 minutes) before are extracted together with the calculation time, and the estimated value of the shear wave cycle from the time 20 minutes after the current time is calculated by differentiating the extracted shear wave cycles with time.

For example, a plurality of shear wave cycles stored in the hull state quantity database 131 during a predetermined time period from the current time and the time at which the shear wave cycle is calculated are extracted, and regression analysis is performed on the value of the shear wave cycle corresponding to the time. And predicting the wavelength data of a time after a predetermined time from the current time based on the slope of the latest data obtained from the regression analysis result.

Alternatively, the following may be used: the slope, which is the extracted time rate of change (time-based differential value) of the shear wave cycle at each time, is differentially calculated, and the time change of the time differential value of the shear wave cycle is compared with the actual data stored in advance, and when a predetermined trend is observed, it is estimated as the time differential value of the shear wave cycle at the next time. Then, a predicted value of the shear wave period at the next time is calculated from the time differential value of the estimated shear wave period.

Further, the predicted value of the shear wave period may be calculated from the GM value and the air pressure data described later by a multiple regression analysis method.

Further, the following may be adopted: for example, a mechanical learning model such as a Convolutional Neural Network (CNN) is used to learn the shear wave period in association with weather information, the stored training data is stored in advance, and the shear wave period is predicted from the stored training data and the current weather information.

In step 160, a predicted value of the shear wave period at a time after the predetermined period is calculated using one of these methods.

The period during which the draft value difference is extracted for calculating the shear wave period in step 140 may be the same as or different from the period during which the shear wave period is extracted for calculating the predicted value of the shear wave period in step 160.

When the predicted value of the cross wave period is calculated in step 160, a system with higher precision can be constructed by considering the air pressure information of the ship navigation region. That is, it is known that the level of the air pressure has a great influence on the development of the wave formation, and when the calculation is performed using the air pressure information as the influence factor, the predicted value of the transverse wave period can be calculated with higher accuracy. The air pressure information can be obtained through the communication unit 120.

The calculation of the predicted shear wave period in step 160 is performed every predetermined time (for example, every 4 minutes). Namely, it may be: in step 140, the predicted shear wave period is calculated every time the shear wave period is calculated.

In this way, the predicted value of the period of the transverse wave borne by the hull is calculated using the time-series data of the state quantity of the hull detected by the draft scale provided on the hull and the time-series data of the period of the transverse wave calculated by fourier analysis, whereby the predicted transverse wave period can be calculated with high accuracy without requiring complicated data processing. In addition, since the draft scale for detecting the state quantity of the hull is already provided on the hull, it is not necessary to provide a new sensor for calculating and predicting the transverse wave period, and thus a transverse wave period prediction system with low cost and high accuracy can be constructed.

In addition, in calculating the period of the transverse wave, only the time series data of the difference between the starboard draft value and the port draft value obtained from the time series data of the hull state quantity detected by the draft scale provided on the port and starboard sides of the hull is used, and therefore, a system capable of accurately predicting the period of the transverse wave can be constructed by using existing equipment without requiring special measuring equipment and high-performance calculating equipment and without considering the combination of the incident angle of the wave and the wave.

Further, since the draft scale of quartz crystal type is used as the draft scale for detecting the state quantity of the hull, the state quantity of the hull can be measured in the form of digital signals unlike the draft scale of other types. Therefore, without the need for A/D conversion at the time of data processing, a highly accurate system for predicting the period of a shear wave without conversion error can be constructed.

[ procedure of GM calculation method Using transverse wave period prediction System 101 ]

Fig. 9 is a flowchart showing a GM calculation method using the shear wave period prediction system 101. Fig. 8 is a diagram showing an example of the hull state quantity database 131. The processing executed by the hardware and software modules will be described with reference to fig. 6, 8, and 9. In the present embodiment, the GM value of the hull is repeatedly calculated by repeatedly executing the control logic of steps 210 to 250.

Here, GM of the hull is defined as a distance between the centroid M and the center of gravity G of the hull, and is a value that changes at every moment based on the inclination of the hull and the like. Wherein, the center of stability M is a point where the direction of the buoyancy with the center of buoyancy as the action point intersects with a line passing through the vertical direction of the center of gravity on the cross section of the ship when the ship body is transversely inclined. If the GM is estimated erroneously, not only is safe navigation impossible, but in the worst case, there is a risk of overturning.

However, it is necessary to consider the influence of a composite wave of waves from various directions, in addition to the waves from the lateral direction, which influence the GM. Therefore, conventionally, in order to accurately grasp or predict the GM, it is necessary to manually input the incident angle in order to grasp the incident direction of the waves on the hull. However, in situations where the hull is likely to be overturned by a large wave, it is impractical to manually input the angle of incidence of the wave.

Therefore, it is not necessary to manually input the incident angle of the wave by a person, and even to dispose a separate sensor, it is necessary to perform real-time calculation of the GM with high accuracy by using the measurement data of the installed sensor without complicated data processing.

[ step S210: detection of State quantity of hull ]

First, when the system is started, the control unit 110 of the transverse wave cycle prediction system 101 cooperates with the measurement unit 160 to execute the hull state quantity detection module 111 and detect the hull state quantities in time series (step S210). In step S210, the state quantity of the hull is detected at predetermined time intervals for a predetermined period based on a draft scale provided on the hull. The predetermined time interval may be set as appropriate, for example, 1 second interval or 1/10 second interval.

In the present embodiment, the oscillation frequency of the quartz crystal is detected as time series data based on draft scales D102 and D103 provided on the port and starboard sides.

[ step S220: detection of roll period of hull ]

Next, the control unit 110 of the roll period prediction system 101 executes the roll period detection module 115 to continuously detect the roll period of the hull, which is defined as the time interval of the maximum roll of the port and starboard sides (step S220).

In the present embodiment, the roll period of the hull is detected based on the time series data of the oscillation frequency detected by draft scales D102 and D103 provided on the port and starboard sides. Since the detected oscillation frequency is a state quantity corresponding to the pressure applied to the crystal oscillator, the change in oscillation frequency with time indicates the change in pressure with time. Therefore, the waveform period of the time series data indicating the oscillation frequency of draft scales D102 and D103 corresponds to the roll period of the hull. In the present embodiment, the peak of the maximum value and the peak of the minimum value of the oscillation frequency are detected from the waveform of the time series data indicating the oscillation frequency, and the roll period is detected from the time between the peaks.

In the present embodiment, the oscillation frequency of the quartz crystal is measured using the quartz crystal draft scale and the roll period of the hull is detected using the oscillation frequency, but the present invention is not limited thereto, and other hull state quantities may be used as long as the roll period can be detected. For example, the roll period may also be detected from the change in draught values for port and starboard over time. Alternatively, the roll period may be detected from a change in the inclination or the roll amount with time.

In the present embodiment, the peak is detected from the waveform of the time series data indicating the hull state quantity, and the roll period is detected from the time between the peaks, but the present invention is not limited to this, and the period may be detected by performing spectrum analysis on the waveform, or the period may be detected using a conventional statistical model indicating the roll timing.

[ step 230: storage of roll period of hull ]

When the roll period of the hull is detected in step S220, the detected roll period is stored in the hull state quantity database 131 (step S230). The roll period is continuously detected, and the detected roll period value is stored in the hull state quantity database 131 together with the detected time as shown in fig. 8.

[ step S240: identification of typical roll periods ]

Next, the control unit 110 executes the typical roll period recognition module 116 in cooperation with the storage unit 130, extracts a roll period of a predetermined period stored in the hull state quantity database 131, and recognizes a typical period of a roll period within the predetermined period using the extracted roll period (step S240).

Here, the predetermined period means, for example, a period of 20 minutes elapsed from the current time, and in this case, a typical period of the predetermined period means a typical value of a roll period within 20 minutes. As described previously, in step S230, the roll period is stored together with the time. Then, all roll periods detected between the current time and the time up to a predetermined time (here, 20 minutes) are extracted, and a typical period of the roll period within the predetermined period is identified by fourier analysis of the extracted roll period data.

The typical cycle recognition in step S240 is performed every predetermined time, for example, every 2 seconds.

[ step S250: calculation of GM value ]

Next, the control unit 110 executes the GM calculation module 117 to calculate the GM value in the formula (3) using the typical period of the roll period of the hull recognized in step S240. The calculated GM value is displayed on the display unit 150 in real time.

GM＝(0.8B/Tγ’)²The type (3)

Here, in equation (3), B is the beam width (m) of the hull, and T γ' is a typical period (sec) of the roll period identified by fourier analysis in step S240.

The calculation of the GM value in step S250 is performed at predetermined time intervals, for example, every 2 seconds, and the latest value is displayed on the display unit 150 every time the calculation is performed. The crew can continue safe navigation by checking the GM value displayed one by one on the display unit 150 and performing various controls on the hull.

In addition, when calculating the GM value and calculating it more strictly, equation (4) with the radius of gyration obtained in the center of gravity inspection (tilt test) at the time of new construction can be used.

GM＝(2.01K/T)²The type (4)

In the formula (4), K is the turning radius (m) of the hull, and T is the natural period (sec) of the hull that varies based on the draft value.

When the turning radius k (m) of the hull can be obtained, the GM value can be calculated by the equation (4). However, when the formula (3) is used, the accuracy may be the same as that when the GM value is calculated by the formula (4).

In this way, the GM value is calculated from the time series data of the hull state quantities detected by the draft scale provided on the hull and the typical period of the roll period identified by fourier analysis, and the GM value can be calculated in real time with high accuracy without requiring complicated data processing. In addition, since the draft scale for detecting the state quantity of the hull is already provided to the hull, it is not necessary to provide a new sensor or the like for calculating the GM value, and a low-cost and high-accuracy GM calculation system can be constructed.

Further, since the roll period, which is the time interval of the maximum roll of the port and starboard sides, is detected using the time series data of the hull state quantities detected by the draft gauges installed on the port and starboard sides of the hull, the GM calculation system can be constructed at a low cost and with high accuracy by using existing facilities without requiring special measuring facilities and high-performance calculation facilities.

In addition, the quartz crystal draft scale is adopted as the draft scale for detecting the state quantity of the ship body, and the state quantity of the ship body can be measured in a digital signal mode unlike the draft scales in other modes. Therefore, a GM calculation system with high precision and no conversion error can be constructed without A/D conversion during data processing.

The hull state quantity to be detected is the oscillation frequency of the crystal oscillator in the quartz crystal draft scale provided on the left and right of the hull, and the change of the oscillation frequency is the rolling period, so that the hull state quantity can be directly and continuously measured. Therefore, a GM calculation system with a small amount of data processing and high accuracy can be constructed without specially converting specific other physical quantities.

[ measurement of draft value of hull ]

A method of measuring the draft values of the bow and the stern of the hull using the draft scales D101 and D104 constituting the transverse wave period prediction system 101 of the present embodiment will be described.

When the draft value is measured, the oscillation frequency is converted into pressure (water pressure), and the water depth of the position where the detection element is installed is calculated therefrom, and the draft value of the hull is derived using the water depth and the distance from the position where the detection element is installed to the bottom of the ship, which is the same as step 120 of fig. 7.

As shown in fig. 6, since the draft scale D101 of the bow is disposed at a position deviated from the bow line, the measured value measured by the draft scale D101 is converted into the bow line position, which is the bow draft value.

Since the draft scale D104 at the stern portion is disposed at a position staggered from the stern line, the measured value measured by the draft scale D104 is converted into the stern line position, which is the stern draft value.

The draft value obtained as described above is subjected to temperature correction using the water temperature measured by the thermometer attached to each draft scale D101, D104 and hull inclination correction (trim: forward and backward inclination, list: lateral inclination) based on an automatic calculation function, thereby obtaining a corrected draft value.

Further, since the seawater specific gravity of the estuary is different from that of the ordinary saltwater waters, and freshwater waters, the seawater specific gravity of the estuary is corrected by manually inputting a measurement value. Standard seawater specific gravity is adopted in the shipping state.

The measurement of the draft value of the hull is carried out as described above.

[ recognition of the period of the meeting of the bow of the hull with waves ]

A method of identifying the period in which the bow of the hull meets a wave using the draft scale D101 or D104 constituting the transverse wave period prediction system 101 in the present embodiment will be described.

First, the pitch period of the bow or stern is measured using the draft scale D101 or D104. That is, similarly to the calculation of the GM value, the sway of the hull can be detected from the change in the oscillation frequency of the crystal oscillator in the draft scale, and the period of the sway can be detected from the period of the change in the oscillation frequency.

Then, the time interval of the maximum pitching of the bow or stern is continuously detected by the change of the oscillation frequency of the draft scale D101 or D104 provided at the bow or stern, and the detected continuous pitching period data is fourier-analyzed, thereby identifying the typical period of the pitching period thereof.

[ calculation of deflection in the fore-and-aft direction of the hull ]

A method of calculating the fore-aft direction deflection of the hull using the draft gauges D101 to D104 constituting the transverse wave period prediction system 101 in the present embodiment will be described.

The fore-and-aft direction deflection of the hull is defined as a difference between the average of the bow draft value and the stern draft value and the hull center draft value, and is a value that briefly indicates whether the hull is in a mid-camber state (convex state) or a mid-sag state (concave state) in the fore-and-aft direction. When calculating this value, the time average value of the draft value for a predetermined period (for example, 150 seconds) is taken for each measurement value.

Then, the arithmetic mean value of the hull central draft is subtracted from the arithmetic mean value of the bow draft and the stern draft to calculate the value of the deflection. The value is an important index for the bending moment of the ship body and the weight of loaded goods, which are closely related to the strength of the ship body, and the value can be accurately grasped to prevent major accidents.

The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. The effects described in the embodiments of the present invention are only the most preferable effects produced by the present invention, and the effects of the present invention are not limited to the effects described in the embodiments of the present invention.

Description of the reference numerals

1 GM calculation System of embodiment 1

10 control part

11 hull state quantity detection module

12 roll period detection module

13 typical roll period recognition module

14 GM calculating module

20 communication unit

30 storage part

31 hull state quantity database

40 input unit

50 display part

60 measurement unit

101 GM calculation system according to embodiment 2

110 control part

111 ship state quantity detection module

112 draft value calculation module

113 transverse wave period calculating module

114 module for calculating predicted transverse wave period

115 roll period detection module

116 typical roll period recognition module

117 GM calculation module

120 communication unit

130 storage part

131 ship state quantity database

140 input unit

150 display part

160 measurement part