In this paper we investigated the effect of the first order responses of mooring line on the second order mooring line damping.In the study of the slow oscillating of a moored floating structure by perturbation method...In this paper we investigated the effect of the first order responses of mooring line on the second order mooring line damping.In the study of the slow oscillating of a moored floating structure by perturbation method in frequency domain,the second order equations of the mooring line are divided into non homogeneous and homogeneous equations.The solutions are related to the first order responses of mooring line and second order floating structure oscillation respectively.In order to find the effect of the first order responses of mooring line,the second order mooring line tension and damping were determined by solving the non homogeneous equation and homogeneous equation.From the results,we found,although the second order mooring line tension obtained from the non homogenous equation is quite small compared with the total second order mooring line tension,the damping contributed from both of them are in the same order in quantity.So,in predicting the second order mooring line damping,the effect of the solution related to the non homogeneous equation can not be omitted.展开更多
The vessel heave motion caused by wave action increases the difficulty of installing offshore wind equipment.On-board wave heave compensation devices have therefore become increasingly critical in ensuring the stabili...The vessel heave motion caused by wave action increases the difficulty of installing offshore wind equipment.On-board wave heave compensation devices have therefore become increasingly critical in ensuring the stability and safety of the gangway and working platform.This study accordingly improves the compensation effect of such devices by developing a wave heave compensation model and designing an optimized backstepping control method.First,a model of the compensation system including the servo motor and electric cylinder is established by using the mechanism method.Second,a backstepping control method is designed to track the vessel heave motion,and particle swarm optimization is applied to optimize the control parameters.Finally,MATLAB/Simulink is used to simulate the application of the optimized backstepping controller,then regular and irregular heave motions are applied as input to a Stewart platform to evaluate the effectiveness of the control method.The experimental results show that the compensation efficiency provided by the proposed optimized backstepping control method is larger than 75.0%.展开更多
文摘In this paper we investigated the effect of the first order responses of mooring line on the second order mooring line damping.In the study of the slow oscillating of a moored floating structure by perturbation method in frequency domain,the second order equations of the mooring line are divided into non homogeneous and homogeneous equations.The solutions are related to the first order responses of mooring line and second order floating structure oscillation respectively.In order to find the effect of the first order responses of mooring line,the second order mooring line tension and damping were determined by solving the non homogeneous equation and homogeneous equation.From the results,we found,although the second order mooring line tension obtained from the non homogenous equation is quite small compared with the total second order mooring line tension,the damping contributed from both of them are in the same order in quantity.So,in predicting the second order mooring line damping,the effect of the solution related to the non homogeneous equation can not be omitted.
基金supported by the National Natural Science Foundation of China(Grant No.62073213).
文摘The vessel heave motion caused by wave action increases the difficulty of installing offshore wind equipment.On-board wave heave compensation devices have therefore become increasingly critical in ensuring the stability and safety of the gangway and working platform.This study accordingly improves the compensation effect of such devices by developing a wave heave compensation model and designing an optimized backstepping control method.First,a model of the compensation system including the servo motor and electric cylinder is established by using the mechanism method.Second,a backstepping control method is designed to track the vessel heave motion,and particle swarm optimization is applied to optimize the control parameters.Finally,MATLAB/Simulink is used to simulate the application of the optimized backstepping controller,then regular and irregular heave motions are applied as input to a Stewart platform to evaluate the effectiveness of the control method.The experimental results show that the compensation efficiency provided by the proposed optimized backstepping control method is larger than 75.0%.
