Study On Ship Response Model And Track Control Algorithm In Restricted Waters

With the integration of global economic,ships as an important part of transportation make the resources of all countries linked together.With the promotion of economy and the development of science and technology,the dimensions of ships are becoming larger and larger,and the scale economy of shipping companies makes the number of ships increasing.The increasing dimensions and number of ships cause congestion in restricted waters such as ports and rivers.Considering economic and security issues,it is an important issue for the development of ship intelligence to design the ship control system under hydrodynamic interference in restricted waters.The hydrodynamic interaction forces are ships moving in restricted waters are complicated,which requires a proper algorithm for real-time calculation of the hydrodynamic forces.At the same time,the maneuvering equation is the basis of trajectory control,thus,it is necessary to account for the hydrodynamic forces in the maneuvering equation of ships,and,based on which,study the ship trajectory control model.Due to the complexity of hydrodynamic interaction forces,the ship maneuvering model in restricted waters is still affected by hydrodynamic interaction effects.The hydrodynamic interaction forces may be calculated in real time using potential flow based method,and the corresponding control method is still required to realize trajectory control accounting for hydrodynamic interaction forces.Based on the above objectives,this thesis studies the ship trajectory control algorithm in restricted waters,analyzes the characteristics of ship maneuvering system in restricted waters,constructs the corresponding ship model based on output redefinition,and studies the ship trajectory control algorithm in restricted waters.The main research work is as follows:1)Based on the theory of nonlinear non-minimum phase system,the characteristics of ship maneuvering model under hydrodynamic interaction are analyzed,and the internal dynamics of ship maneuvering model under hydrodynamic interaction under B-I standard is investigated.Due to the instability of internal dynamics,it is concluded that the ship maneuvering model under hydrodynamic interaction is a non-minimum phase system.2)Based on the output redefinition method,the ship maneuvering model is the same as the redefinition output within a specific frequency.Based on the assumption that the ship is in a low-frequency state under the condition of restricted waters,the low-frequency maneuvering model of the ship maneuvering model is independent to obtain the ship response model after the output is redefined.3)The path control feedforward term is designed based on the stable inversion method,and the ship response model in restricted waters is modified accordingly.The ship response model in restricted waters combined with the stable inversion is obtained.The simulation analysis shows that the ship response model in restricted waters under precise control can effectively avoid collision.4)The hydrodynamic interaction of ships calculated in real time by a potential flow method is input into the sliding mode controller as a known disturbance.By simulating the ship trajectory under typical hydrodynamic interaction conditions of ships in restricted waters,the ship trajectory with or without control is compared to verify the control effect of the controller design under different water depths,speeds and transverse clearances.The conclusions and suggestions are drawn based on the analysis of the calculation and simulation results,which may provide a theoretical and technical support for the collision avoidance control of ships moving in restricted waters.