Research On Intelligent Control And Simulation Of Dynamic Positioning For A Rescue Ship

With the development and exploitation of ships and ocean engineering,dynamic positioning system has been widely used in many kinds of ships and ocean platforms,and made higher demand of keeping ship's position day by day,this above requirement finally rely on the control technology. Therefore,people have been working on searching better control technologies, and Active Disturbance Control(ADRC) is an alternative.The author,taking beihail 15 salving vessel as the study object,focusing on some relative working schema of DP system on 115, designs ADRC controller,and tests its control qualities under different speed and different circumstances.In this thesis,based on MMG modeling mechanism,firstly the author sets up planar three degrees of freedom model of ship motion and pure sliding motion model which is suitable for dynamic positioning system.For the planar three degrees of freedom model of ship motion, forward navigation of constant speed and low speed are discussed separately.Using the data of experimental manipulation from real ship, the author makes simulation verification with the planar three degrees of freedom model of ship motion.During this process, adjustment of several parameters is made to improve the forecast accuracy of the mathematical model.Then,the ADRC controller is designed, the algorithm of tracking differentiat-or,extended state observer and effects of non-smooth feedback are illustrated spe-cifically,and a brief discussion of parameter adjustment of every part is made for ADRC.Finally,setting this paper's project background as the process that a salving vessel sails to a fixed point which is waiting support, the author uses the desi-gned ADRC controller to the following three sub-processes,including heading hol-d,vertical shift movement and sliding movement which involved in the project b-ackground,makes simulation and comparison with classical PID controllers under ideal sea conditions,speed changed and sea conditions with certain wind,wave and flow separately. The results of simulation indicate that the control performance and robustness of ADRC is significantly better than classical PID,the output of plot of rudder angle and pitch are smoother and gentler,the steady state accuracy of control output is higher,the adaptability of parameters is extensive.However,its response is slightly slower than PID,and a multi-mode control strategy is proposed to improve this problem,the strategy take the advantage of fast of Bang-Bang control,it demonstrates superior control performance,the author takes sway movement as the research object to verify its effectiveness.