Synchronization Control For Supply Ship In Underway Replenishment

Underway replenishment operation of ships is that fuel,food or other personnel are transferred from one ship to another while both ships are moving.The replenishment operation of ships reduces the dependence of the ship on the base and shortens port time for long-term military operations.It can increase the operational radius and continuous maneuvering ability of ships.The replenishment ships are inevitably affected by the environmental disturbances,and then the two ships will not be synchronized,thus lead to the failure of the replenishment.So it is significantly practical to get involved in the research of ship replenishment operation.The main scientific contributions of this thesis are:firstly,considering the bound-known environmental disturbances acting on the supply ship,we introduce the virtual trajectory located on one side of the supplied ship with a relatively fixed distance from the track of the supplied ship to solve the synchronization control problem of the supply ship.The nonlinear synchronization control law for the supply ship is designed based on the dynamic surface control(DSC)method.The supply ship can track the virtual trajectory,and then synchronization control between the supply ship and the supplied ship is achieved.Furthermore,considering the bounded time-varying environmental disturbances acting on the supply ship,the adaptive technique is applied to design adaptive laws to estimate the bound of unknown disturbance.Based on this,an adaptive robust synchronization control law is designed based on DSC.Additionally,considering the unknown time-varying environmental disturbances acting on the supply ship,a nonlinear disturbance observer is constructed to provide the estimates of the environmental disturbances.Using the vectorial backstepping design tool,a robust synchronization control law is designed for the supply ship to make it track the virtual trajectory.As such,the safe and smooth underway replenishment operation is ensured.Finally,simulations of the three designed control laws are carried out in Matlab/Simulink environment.The simulation results verify the effectiveness of the proposed control laws.