Research On Green Dynamic Positioning System With Nonlinear Predictive Control Method

With the development of the world economy and the increasing demand of resources,and the increasing depletion of land resources, so it prompts people to exploit the rich marine resources. Now it is widely used in developing of energy sources for ships which equipped with a Dynamic Positioning System. As the important part of the Dynamic Positioning System, that the ship controller’s performance which determines the quality of the actual positioning job. This article will adopt the nonlinear model predictive control technology as the controller of Dynamic Positioning System, and also study the Green Dynamic Positioning System. The research contents of this paper are:1. Firstly, the coordinate system is described for the building of the model of ship, then the establishment of ship model with three degrees of freedom is adopted the linear superposition of low-frequency and wave-frequency models, which include the kinematic model and the dynamic model. For describing the environmental interference force, it built the mathematical model of wind, wave and current. Finally, the inherent parameter of one DP ship which is used for research object of this paper is given,then through the simulation of the ship motion, the paper testify the validity of the ship model.2. It designed a predictive controller for the dynamic positioning ships based on feedback linearization. First of all, the model of the ship t is simplified before the design of the controller, and then it introduced the exact feedback linearization theory, the ship model is exactly linearized, then it designed a ship predictive controller based on feedback linearization,the transformation of the control constraint is approximately treated. Finally, it provided the result of the simulation of this controller.3. It designed the analytic model predictive controller for the ship by absorbed the advantage of the feedback linearization theory. It show the effectiveness of its controller through the simulation results. Since the adjustment of the weight parameters which in the objective function of this controller is very complex and cumbersome, it optimized the weight parameters through the particle swarm algorithm, and it also take the overshoot and other indicators into consideration in the fitness function. Finally, it provided the parameters optimized simulation result of the controller, and through comparison illustrate that it has better control effect after optimization.4. Finally, it realized the green dynamic positioning control system. Firstly, it introduced the composition and operational principle, it designed nonlinear observer with the account of the high frequency interference. Then it take the feedback linearization predictive controller as the environmental interference compensation and take the analytic model predictive controller as a controller act on the outside of the work operation. The results of the simulation shows the effectiveness of the green positioning control system’s control effect on the propeller wear and resource conservation.This paper focused on the study of model predictive controller at dynamic positioning vessels, and take the predictive controller design for the realization of green positioning control system. Through a lot of simulation, it show the effectiveness of the designed controller.