Simulation Research Of Dynamic Positioning Control System For A Rescue Ship

With the rapid development of the shipping and marine engineering, the dynamic positioning system has been widely used in many ships and offshore platform, and played an important role.This thesis takes "beihaijiu115" rescue ship as the study object, using a technology that called "active disturbance rejection control" to design controller. And take simulation research in different sea conditions.In this paper, firstly the author analyses the development status and tendency of ship dynamic positioning system. Then introduces the ship mathematical model of low-frequency motion and high-frequency motion, yet the disturbance model of wind、wave and current. We mainly construct the ship low-frequency motion model which is suitable for simulation of control system. And verify the validity of the model through simulation results.Then, the author discussed Active Disturbance Rejection Controller in detail, including Tracking Differentiator(TD)、Extended State Observer(ESO) and Nonlinear State Error Feedback(NLSEF), and their algorithm are illustrated specifically. There also discuss the methods of parameter adjustment of every part.Finally, design the dynamic positioning ADRC controller for ideal sea condition and ordinary sea condition, comparing its simulation results with PID simulation results.The results of simulation indicate that the robustness and anti-interference performance of ADRC is significantly better than classical PID, and ARDC has a very good control capacity to the unmodeled dynamics. The output has characteristic of response fast and small overshoot. As ADRC controller has a disadvantage of setting parameters difficultly, in order to realize online setting of the parameters in NLSEF of ADRC, an improved ADRC control based on fuzzy control theory is designed. This improvement can strengthen the performance of ADRC. And verify the validity of the Fuzzy-ADRC controller through simulation results.