Modeling of Ship Manoeuvring Motion in 4 Degrees of Freedom Based on Support Vector Machines

2013 ◽  
Author(s):  
Xuegang Wang ◽  
Zaojian Zou ◽  
Feng Xu
Keyword(s):  
Mathematical Model ◽  
Support Vector Machines ◽  
Degrees Of Freedom ◽  
Support Vector ◽  
Roll Motion ◽  
Ship Manoeuvring ◽  
Hydrodynamic Derivatives ◽  
Vector Machines ◽  
Roll Rate ◽  
4 Degrees Of Freedom

Ship manoeuvring motion in waves is usually accompanied by nonlinear roll motion of large amplitude. In this paper, by taking account of the influence of the roll motion, a 4 degrees of freedom mathematical model of ship manoeuvring motion is derived. A method based on least squares support vector machines (LS-SVM) is proposed for identifying the hydrodynamic derivatives in the mathematical model by analyzing the data of surge speed, sway speed, yaw rate, roll rate, roll angle and rudder angle. To verify the identification method, 10°/10° zigzag tests are simulated for a container ship by using the hydrodynamic derivatives obtained from the roll planar motion mechanism (RPMM) test; the simulation data are used to identify the hydrodynamic derivatives, and the identification results are compared with those of RPMM test. The 10°/10° zigzag manoeuvring motion is predicted with the identified hydrodynamic derivatives. Besides, the identified model is used to predict the 20°/20° zigzag and 35° turning circle manoeuvres, and the predicted results are compared with those of simulation tests to demonstrate the generalization performance of the identified mathematical model.

Parameter Identification of Ship Manoeuvring Model Based on Particle Swarm Optimization and Support Vector Machines

2013 ◽  
Author(s):  
Weilin Luo ◽  
Carlos Guedes Soares ◽  
Zaojian Zou
Keyword(s):  
Particle Swarm Optimization ◽  
Support Vector Machines ◽  
Structural Parameters ◽  
Accurate Determination ◽  
Particle Swarm ◽  
Support Vector ◽  
Swarm Optimization ◽  
Ship Manoeuvring ◽  
Hydrodynamic Derivatives ◽  
Vector Machines

The method of system based manoeuvring simulation provides an effective way to predict ship manoeuvrability. Accurate determination of the hydrodynamic derivatives in the mathematical model of ship manoeuvring motion is vital to the prediction accuracy. A support vector machines (SVM) based approach is proposed in this paper. By analyzing the data from free-running model tests of KVLCC2 ship, the hydrodynamic derivatives in an Abkowitz model are identified. To diminish the parameter drift in the identification, a difference method is adopted to reconstruct the sample for identification. To obtain the optimized structural parameters in SVM, particle swarm optimization (PSO) method is incorporated into SVM. Predictions of manoeuvring motion are presented based on the regression model. Comparisons between the predicted results and the test results demonstrate the validity of the proposed methods.

Simulation of Ship Manoeuvring in the Proximity of a Pier by Using Support Vector Machines

2011 ◽  
Author(s):  
Wei-lin Luo ◽  
Zao-jian Zou ◽  
Hong-liang Xiang
Keyword(s):  
Mathematical Model ◽  
Support Vector Machines ◽  
Support Vector ◽  
Test Results ◽  
Interaction Coefficients ◽  
Ship Manoeuvring ◽  
Vector Machines ◽  
Close Relationship ◽  
The Mathematical Model ◽  
Navigation Safety

Ship manoeuvrability has a close relationship with navigation safety. For a ship sailing in the proximity of a pier, its manoeuvrability is different from that in unrestricted waters. To predict the ship manoeuvrability in the proximity of a pier, the method of simulation based on mathematical model is used. The mathematical model of ship manoeuvring is obtained by using Support Vector Machines (SVM) based system identification, combined with free-running model tests. The interaction between the pier and the ship are considered in the mathematical model of ship manoeuvring motion. By analyzing the test results, SVM is applied to identify the hydrodynamic coefficients and the interaction coefficients in the mathematical model. By using the regressive models, the ship manoeuvring motions in the proximity of a pier are predicted. Comparisons between the predicted results and the test results demonstrate the validity of the proposed SVM method. Identification results, model test results as well, also confirm that navigation safety of the ship in the proximity of a pier can be guaranteed if the distance between the pier and the ship is under control.

Parameter Identification of Ship Maneuvering Model Based on Support Vector Machines and Particle Swarm Optimization

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Weilin Luo ◽  
C. Guedes Soares ◽  
Zaojian Zou
Keyword(s):  
Particle Swarm Optimization ◽  
Support Vector Machines ◽  
Difference Method ◽  
Particle Swarm ◽  
Support Vector ◽  
Ship Maneuvering ◽  
Swarm Optimization ◽  
Hydrodynamic Derivatives ◽  
Vector Machines ◽  
Maneuvering Motion

Combined with the free-running model tests of KVLCC ship, the system identification (SI) based on support vector machines (SVM) is proposed for the prediction of ship maneuvering motion. The hydrodynamic derivatives in an Abkowitz model are determined by the Lagrangian factors and the support vectors in the SVM regression model. To obtain the optimized structural factors in SVM, particle swarm optimization (PSO) is incorporated into SVM. To diminish the drift of hydrodynamic derivatives after regression, a difference method is adopted to reconstruct the training samples before identification. The validity of the difference method is verified by correlation analysis. Based on the Abkowitz mathematical model, the simulation of ship maneuvering motion is conducted. Comparison between the predicted results and the test results demonstrates the validity of the proposed methods in this paper.

scholarly journals Identification of Ship Hydrodynamic Derivatives Based on LS-SVM with Wavelet Threshold Denoising

2021 ◽  
Vol 9 (12) ◽  
pp. 1356
Author(s):  
Yi Hu ◽  
Jianxi Yao ◽  
Zuyuan Liu ◽  
Lifei Song
Keyword(s):  
Training Data ◽  
Support Vector ◽  
Type Model ◽  
Identification Methods ◽  
Ship Manoeuvring ◽  
Hydrodynamic Derivatives ◽  
Vector Machines ◽  
Sample Data ◽  
Ship Hydrodynamic

Nowadays, system-based simulation is one of the main methods for ship manoeuvring prediction. Great efforts are usually devoted to the determination of hydrodynamic derivatives as required for the mathematical models used for such methods. System identification methods can be applied to determine hydrodynamic derivatives. The purpose of this work is to present a parameter identification study based on least-squares support-vector machines (LS-SVMs) to obtain hydrodynamic derivatives for an Abkowitz-type model. An approach for constructing training data is used to reduce parameter drift. In addition, wavelet threshold denoising is applied to filter out the noise from the sample data during data pre-processing. Most of the resulting derivatives are very close to the original ones—especially for linear derivatives. Although the errors of high-order derivatives seem large, the final predicted results of the turning circle and zigzag manoeuvres agree pretty well with the reference ones. This indicates that the used methods are effective in obtaining manoeuvring hydrodynamic derivatives.

Sign in / Sign up

Export Citation Format

Share Document