Concise Nonlinear Robust Control For Ship Auto-berthing

In order to solve the key problems that the design of underactuated ship automatic berthing controller under the circumstance of the restricted waters in port,the uncertainty of mathematical model parameters and the relatively strong environment perturbation,this research topic is selected as "concise and nonlinear robust control for ship auto-berthing".The theoretical exploration based on the requirements of navigation practice has been carried out systematically in this thesis,which provides the theoretical guidance and technical support for ship berthing support system or automatic full-routed control of intelligent ship so as to improve the berthing efficiency and reduce the safety risk.This research work includes 3 key aspects:ship maneuvering mathematical model in port,control algorithm and control engineering applications.By employing the concise idea,robust control and adaptive control,the control low can be concise,efficient and easy to implement,and the controller has robustness under environmental disturbances and the perturbations of model parameters,at the same time the control parameters have adaptabiliy under uncertainties of disturbances and model paramerters.The objective is to realize the automatic berthing control considering the practice requirements(actuator input saturation,real-time algorithm,etc.)by solving several key problems for ship maneuvering and control in port.A kind of practical ship maneuvering modeling group(MMG)model is discussed.The correction of shallow water,low speed and external environmental disturbances together with the mutual interference of the hull,rudder,propeller are taken into account in this model,which introduced the practical reversing propeller thrust mathematic model reflected the characteristics of the right-handed single-screw propeller.Moreover,the cubic spline interpolation algorithm is used for the interpolation calculation of hull fluid force when drift angle between 20° to 30°.The effectiveness of the proposed model is verified by the simulation of a LPG(Liquid Petroleum Gas)ship(turning test,zigzag test,crash astern test,shallow water test and low speed test).In order to solve the uncertainties of disturbances and model paramerters of the underactuated ship control,an additional control method is adopted for the underacruated problem,while the navigation dynamic deep-rooted information based the robust neural networks(NN)adaptive approach is used to reconstruct the dynamic and unknown disturbances of uncertain models.In order to solve the problem of course keeping control with the propeller stopping or reversing at slow speed for berthing,a concise nonlinear feedback and nonlinear decoration algorithm driven by nonlinear function is proposed by using a feedback(or nonlinear decoration)method of state feedback or output feedback.Then,the stability analyses are carried out by using the Lyapunov direct method and response analysis method of the closed-loop system.In order to enhance the safety of ship maneuvering and control in port(reducing the rudder angle and the load of steering gear,etc),a novel nonlinear feedback PID(Proportional,Integral and Derivative)algorithm,combined with the closed-loop gain shaping algorithm and the nonlinear feedback technology driven by bipolar sigmoid function is proposed;In order to reduce the computational load and shorten the training time of the multi-parameter NN auto-berthing controller,a concise NN controller is proposed by optimizing input parameters and extraction frequency of effective information;In order to solve the computational load problem of adaptive NN auto-berthing control with input saturation of control actuator(rudder,propeller,etc),the dynamic surface control(DSC)technique and the minimum learning parameter(MLP)are used for the engineering realization easily.All the experiments in this thesis are implemented by using Matlab/Simulink to verify the effectiveness of the controller designed.This research has important practical significance for promoting the development of high-tech shipbuilding industry,and has laid an important theoretical foundation for building the low carbon,energy saving,environmental protection and safety marine transportation.