The Reasearch On The Safety Of Ship Navigation On The Open Sea Based On Ship Maneuverability

As one of the most important navigation performance of ship,the ship maneuverability has draws much attention from the International Maritime Organization(IMO),the governments and researchers.According to the statistical data,the number of shipping casualties related to ship maneuverability is more than 30%of total number of shipping casualties in the past decade.As a result,ship maneuverability plays an essential role in the safety of ship navigation on the open sea.Meanwhile,the autonomous unmanned vessel has draws much attention in recent years.Due to the characteristics of ship motion,such as large inertia,the navigation safety of autonomous unmanned vessel can not ignore the effect of ship maneuverability.Base on above observation,and in order to reduce the number of shipping casualties related to ship maneuverability,decrease the loss of personnel and property,and protect the maritime environment,this doctoral dissertation focuses on the following works for the safety of ship navigation on the open sea based on the ship maneuverability,the main research works are stated as follows:Firstly,based on the ship maneuverability standards of IMO and American Bureau of Shipping(ABS),a novel rating based F-ANP model is proposed for the evaluation of ship maneuverability.The proposed model is able to solve the problem of mutual dependencies of the maneuvering factors inherent in the evaluation of ship maneuverability and the insufficiency of unreasonable weights of maneuvering factors assigned in current evaluation model.Following this model,the more synthesized and advanced evaluation process for ship maneuverability is achieved and the more reasonable weights for each maneuvering factor are assigned.Furthermore,the maneuvering data of three ships are applied to the case studies and discussions by comparing with the common Fuzzy Analytic Hierarchy Process(F-AHP)model and current ABS standards.The comparative results are encouraging,and show that the proposed rating based F-ANP approach is a viable and effective tool for evaluation of ship maneuverability.Secondly,for a class of uncertain discrete-time nonlinear strict-feedback systems with input saturation and known gains,a novel adaptive neural network control approach is presented,and then the control scheme is applied to ship course discrete-time nonlinear system with rudder dynamic and unknown gains.By combining single neural network approximation and minimal learning parameter technique,the proposed approach is able to eliminate the complexity growing problem and alleviate the explosion of learning parameters.An auxiliary design system is incorporated into the control scheme to overcome the problem of input saturation constraints.Following this approach,the designed controller contains only one actual control law and one adaptive law,the numbers of input variables and weights of neural network updated online are decreased drastically,and the number of parameter updated online for whole system is reduced to only one.As a result,the adaptive mechanism with much simpler controller structure and minimal learning parameterization is achieved,and the computational burden is lighter.Thirdly,the research on collision avoidance of ship maneuvering in close-quarters situation.At the first place,a ship maneuverability based ship maneuvering collision avoidance dynamic support system in close-quarters situation is presented by combining mathematical model and control system of ship maneuvering motion along with dynamic model of distance to closest point of approach(DCPA)and time to the.closest point of approach(TCPA).Following this approach,the proposed system is able to eliminate the insufficiency of neglect of ship maneuverability in the process of avoiding collision.Moreover,simulation examples consisting three encounter scenarios of two ships in close-quarters situation are applied to demonstrate the significance and necessity of ship maneuverability in the process of collision avoidance,and simulation results show that the proposed dynamic support system is a reasonable,effective and practicable system for collision avoidance,particularly in close-quarters situation.Subsequently,a novel synergy ship domain is presented based on synergetics theory and ship maneuverability.In accordance to the conception of synergetics theory,the proposed ship domain is able to solve the problem of neglect of mutual interaction of meeting ships in conventional ship domain.Then based on the universal advance derived from a great deal of collected advance data of turning test,the insufficiency of ship maneuverability inherent in conventional ship domain is eliminated.Comparing with conventional ship domain,the novel proposed synergy ship domain is meaningful with prevent from collison casualties.By carrying out above research work related to ship maneuverability,this doctoral dissertation is able to be the theoretical foundation of the safety of ship navigation on the open sea,and enhance the safety level of ship navigation on the open sea.