CN113212681B - Ship rolling period monitoring method - Google Patents

Ship rolling period monitoring method Download PDF

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CN113212681B
CN113212681B CN202110467580.5A CN202110467580A CN113212681B CN 113212681 B CN113212681 B CN 113212681B CN 202110467580 A CN202110467580 A CN 202110467580A CN 113212681 B CN113212681 B CN 113212681B
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ship
fitting
roll
data
sequence
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CN113212681A (en
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朱爱玺
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Jiangsu Vocational College of Information Technology
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B39/00—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude
    • B63B39/14—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude for indicating inclination or duration of roll
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C15/00—Surveying instruments or accessories not provided for in groups G01C1/00 - G01C13/00
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
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  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Ocean & Marine Engineering (AREA)
  • Length Measuring Devices With Unspecified Measuring Means (AREA)
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Abstract

The invention relates to the technical field of ship detection, in particular to a ship rolling period monitoring method, which comprises the following steps: s1, collecting a ship rolling angle; s2, performing rough difference removal treatment on the rolling angle sequence; s3, if the length of the acquired effective data sequence is greater than 20, performing attenuated cosine curve fitting on the processed roll angle sequence; s4, continuously performing new fitting along with the increase of the acquired data; s5, taking an effective data sequence to participate in fitting by adopting a sliding window method; s6, calculating a measurement result according to the fitting result.

Description

Ship rolling period monitoring method
Technical Field
The invention relates to the technical field of ship detection, in particular to a ship rolling period monitoring method.
Background
Along with globalization of economy, international trade is developed, and large container ships are used as main transportation means of ports, so that sailing safety is particularly important, floating state and stability of the ships are important parameters for evaluating the safety of the ships, and the stability of the ships is controlled in time, so that serious accidents such as container ship capsizing, channel blockage and the like can be effectively avoided.
The stability of the ship mainly depends on the rationality of the allocation scheme, and the method for controlling the stability of the ship at the present stage mainly comprises the following steps: the loading method of the loader and the rolling period test method have larger stability calculation errors due to the fact that the loading method of the loader has box weight measurement errors, gravity center height estimation, loading scheme deviation and the like; the roll periodic test method is difficult to implement due to the fact that the roll periodic test method needs personnel to excite.
Disclosure of Invention
In view of the above, in order to overcome the defects of the prior art, the present invention aims to provide a ship rolling period monitoring method, which uses a sensor installed on a dock or a ship to measure a ship rolling angle, calculate a ship rolling period, and realize rapid measurement of the ship rolling period.
The technical aim of the invention is realized by the following technical scheme:
a method of monitoring a vessel roll period comprising the steps of:
s1, collecting a ship rolling angle, wherein the collecting frequency cf is 10 Hz-50 Hz;
s2, performing rough difference removal processing on the roll angle sequence obtained in the step 1, removing roll angle data with overlarge deviation value and marking the data as empty, namely
Figure BDA0003043839470000011
S3, if the length of the acquired effective data sequence is greater than 20, performing attenuated cosine curve fitting on the processed roll angle sequence, wherein a fitting equation is as follows:
Figure BDA0003043839470000012
wherein phi is the roll inclination angle at any moment, N is a damping coefficient, omega is the ship roll angular velocity, A is the roll inclination angle amplitude,
Figure BDA0003043839470000013
for a steady-state inclination of the ship roll, t is a time sequence t (i) of acquired data, i= … n;
since in the small roll case the vessel roll damping is linearly related, the vessel roll damping is
d＝N*ω (2)
The resulting sets Φ ultimately represent the acquired roll tilt sequences (i), i= … n.
S4, setting an acquisition time period t0 seconds because the ship rolling period is generally 5-20 seconds, wherein t0 can be adjusted according to a specific ship type, when the time period for acquiring data is less than t0 seconds, namely the acquired data amount is less than t0 cfs, the number n of data sequences subjected to fitting in the step 3 is continuously increased along with the acquisition time, and in order to improve the operation efficiency, new fitting is performed every 10 times n is increased, and the fitting frequency j= … k; the results for the j-th fit are: a (j), N (j), ω (j),
Figure BDA0003043839470000021
s5, when the duration of data collection is longer than t0 seconds, namely the number of data collection is greater than t0 cfs, taking an effective data sequence to participate in fitting by adopting a sliding window method, enabling the t0 cfs effective data sequence to enter a queue, namely when the newly added effective data of the collection roll inclination angle is greater than 10, the earliest 10 effective data in the queue are moved out of the queue, each data in the later sequence is moved forward by 10 positions, the currently collected effective data is pressed into the queue to serve as a queue tail, then fitting is carried out on the new data sequence in the queue, and the queue is updated by adopting the method continuously to perform fitting subsequently;
s6, regarding the fitting result of the previous step, taking the latest fitting result as the standard every time, calculating the real-time rolling period T=2pi/omega of the ship, the rolling damping coefficient N of the ship and the steady-state inclination angle of the ship
Figure BDA0003043839470000022
Further, in S4, t0 may be set to 10S in the case of a small ship, and 20S in the case of a general large and medium ship, and 40S in the case of an oversized passenger ship according to the specific ship type.
In summary, the invention has the following beneficial effects:
the invention does not need a complex information system, carries out rough difference removal treatment by continuously collecting the rolling angle sequence, improves the operation efficiency by a sliding window method, and reduces the cosine curve fitting method, calculates the rolling period of the ship in real time, provides a new method for quick, efficient and stable measurement of the ship, and is suitable for wide popularization.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate and together with the description serve to explain the invention, if necessary:
FIG. 1 is a schematic view of the roll angle of a vessel in accordance with the present invention;
FIG. 2 is a graph of roll angle decay of a vessel in accordance with the present invention;
FIG. 3 is a schematic diagram of a data queue sliding window method for curve fitting in the present invention.
Detailed Description
The foregoing and other features, aspects and advantages of the present invention will become more apparent from the following detailed description of the embodiments, which proceeds with reference to the accompanying figures 1-3. The following embodiments are described in detail with reference to the drawings.
Exemplary embodiments of the present invention will be described below with reference to the accompanying drawings.
Example 1: as shown in fig. 1 to 3, the amplitude angle of the roll varies from one position of the vessel to another, but the roll period is uniform, since in still or irregular wave waters the roll of the vessel after excitation is a damped motion which satisfies the damped cosine function, and for small amplitude roll the vessel roll damping is linear with angular velocity.
Therefore, a ship roll period monitoring method is provided, which comprises the following steps:
s1, collecting a ship rolling angle, wherein the collecting frequency cf is 10 Hz-50 Hz;
s2, performing rough difference removal processing on the roll angle sequence obtained in the step 1, removing roll angle data with overlarge deviation value and marking the data as empty, namely
Figure BDA0003043839470000031
S3, if the length of the acquired effective data sequence is greater than 20, performing attenuated cosine curve fitting on the processed roll angle sequence, wherein a fitting equation is as follows:
Figure BDA0003043839470000032
wherein phi is the roll inclination angle at any moment, N is a damping coefficient, omega is the ship roll angular velocity, A is the roll inclination angle amplitude,
Figure BDA0003043839470000033
for a steady-state inclination of the ship roll, t is a time sequence t (i) of acquired data, i= … n;
since in the small roll case the vessel roll damping is linearly related, the vessel roll damping is
d＝N*ω (2)
The resulting multiple sets Φ ultimately represent the acquired roll tilt sequences
Figure BDA0003043839470000034
i＝0…n。
S4, setting an acquisition time period t0 seconds because the ship roll period is generally 5-20 seconds, wherein t0 can be adjusted and set according to specific ship types, for example, if the ship roll period is a small ship, the ship roll period can be set to be 10S, and for general large and medium ships, the ship roll period is set to be 20S, and an oversized passenger ship can be set to be 40S, when the time period for acquiring data is less than t0 seconds, namely the acquired data amount is less than t0 cfs, the number n of data sequences subjected to fitting in the step 3 is continuously increased along with the acquisition time, and in order to improve the operation efficiency, new fitting is performed every 10 times n, and the fitting times j= … k; the results for the j-th fit are: a (j), N (j), ω (j),
Figure BDA0003043839470000036
s5, when the duration of data collection is longer than t0 seconds, namely the number of data collection is greater than t0 cfs, taking an effective data sequence to participate in fitting by adopting a sliding window method, enabling the t0 cfs effective data sequence to enter a queue, namely when the newly added effective data of the collection roll inclination angle is greater than 10, the earliest 10 effective data in the queue are moved out of the queue, each data in the later sequence is moved forward by 10 positions, the currently collected effective data is pressed into the queue to serve as a queue tail, then fitting is carried out on the new data sequence in the queue, and the queue is updated by adopting the method continuously to perform fitting subsequently;
s6, regarding the fitting result of the previous step, taking the latest fitting result as the standard every time, calculating the real-time rolling period T=2pi/omega of the ship, the rolling damping coefficient N of the ship and the steady-state inclination angle of the ship
Figure BDA0003043839470000035
While the invention has been described in connection with certain embodiments, it is not intended that the invention be limited thereto; for those skilled in the art to which the present invention pertains and the related art, on the premise of based on the technical scheme of the present invention, the expansion, the operation method and the data replacement should all fall within the protection scope of the present invention.

Claims (1)

1. A method of monitoring a vessel roll period, comprising the steps of:
s1, collecting a ship rolling angle, wherein the collecting frequency cf is 10 Hz-50 Hz;
s2, performing rough difference removal processing on the roll angle sequence obtained in the step S1, removing roll angle data with overlarge deviation value and marking the data as empty, namely
Figure FDA0004176453900000011
S3, if the length of the acquired effective data sequence is greater than 20, performing attenuated cosine curve fitting on the processed roll angle sequence, wherein a fitting equation is as follows:
Figure FDA0004176453900000012
wherein phi is the roll inclination angle at any moment, N is a damping coefficient, omega is the ship roll angular velocity, A is the roll inclination angle amplitude,
Figure FDA0004176453900000013
for a steady-state inclination of the ship roll, t is a time sequence t (i) of acquired data, i= … n;
the ship rolling damping is as follows:
d＝N*ω (2)
the resulting multiple sets Φ ultimately represent the acquired roll tilt sequences
Figure FDA0004176453900000014
S4, setting the acquisition time period t0 seconds, adjusting the t0 according to the specific ship shape, and when the time period for acquiring the data is less than t0 seconds, namely the acquired data amount is less than t0 cfs, wherein the number n of the data sequences subjected to fitting in the step S3 is along with the acquisition timeThe interval is increased continuously, in order to improve the operation efficiency, new fitting is carried out every 10 times when n is increased, and the fitting times j= … k; the results for the j-th fit are: a (j), N (j), ω (j),
Figure FDA0004176453900000015
in the step S4, the method for adjusting t0 according to the specific ship shape includes: in the case of a small-sized ship, the ship is set to 10s, and in the case of a large-sized and medium-sized ship, the ship is set to 20s, and an oversized passenger ship is set to 40s;
s5, when the duration of data collection is longer than t0 seconds, namely the number of data collection is greater than t0 cfs, taking an effective data sequence to participate in fitting by adopting a sliding window method, enabling the t0 cfs effective data sequence to enter a queue, namely when the newly added effective data of the collection roll inclination angle is greater than 10, the earliest 10 effective data in the queue are moved out of the queue, each data in the later sequence is moved forward by 10 positions, the currently collected effective data is pressed into the queue to serve as a queue tail, then fitting is carried out on the new data sequence in the queue, and the queue is updated by adopting the method continuously to perform fitting subsequently;
s6, for the fitting result of the previous step, calculating the real-time rolling period T=2pi/omega of the ship, the rolling damping coefficient N of the ship and the steady-state inclination angle of the ship based on the latest fitting result
Figure FDA0004176453900000021
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4918628A (en) * 1985-12-18 1990-04-17 University Of Southampton Stability meter for floating objects
WO2004002815A1 (en) * 2002-06-27 2004-01-08 Kranskan Limited Method and apparatus for monitoring the safety of a marine vessel
CN105292397A (en) * 2015-10-14 2016-02-03 武汉理工大学 Method, system and device for monitoring and pre-warning inland ship stability in real time
CN107140110A (en) * 2017-03-21 2017-09-08 山东省科学院海洋仪器仪表研究所 A kind of ship large-amplitude roll kinematic nonlinearities damped coefficient recognition methods
CN111639390A (en) * 2020-05-15 2020-09-08 上海理工大学 Ship rolling motion parameter identification method based on vibration test

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE1130084A1 (en) * 2011-09-16 2013-03-12 Tagg R & D Ab Q Method and apparatus for avoiding and attenuating the rolling of a ship

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4918628A (en) * 1985-12-18 1990-04-17 University Of Southampton Stability meter for floating objects
WO2004002815A1 (en) * 2002-06-27 2004-01-08 Kranskan Limited Method and apparatus for monitoring the safety of a marine vessel
CN105292397A (en) * 2015-10-14 2016-02-03 武汉理工大学 Method, system and device for monitoring and pre-warning inland ship stability in real time
CN107140110A (en) * 2017-03-21 2017-09-08 山东省科学院海洋仪器仪表研究所 A kind of ship large-amplitude roll kinematic nonlinearities damped coefficient recognition methods
CN111639390A (en) * 2020-05-15 2020-09-08 上海理工大学 Ship rolling motion parameter identification method based on vibration test

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
波浪影响下船舶横摇运动的时间序列预测数学建模研究;李海霞;;舰船科学技术(第22期);全文 *

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