Numerical Simulation Of Dynamic Positioning Of Deep-sea Pipe-laying Vessel Based On LQG Algorithm And Complex Method

With the implementation of deep-sea strategy,the technology and equipment related to the exploitation and utilization of deep-sea oil and gas resources have received unprecedented attention and development.The deep-water pipe-laying ship plays a important role in the deep-sea engineering,because it undertakes most of the tasks of pipe laying.At the same time,dynamic positioning has become one of the indispensable technologies in deep-sea engineering because of its unique advantages.In this paper,a numerical simulation program of dynamic positioning based on the LQG control algorithm and complex method is accomplished,and the simulations of deepsea pipe-laying ship are finished.Ship motion model,environment loading model,stinger model and pipe model are established to simulate the ship motion,and state space model are established for control algorithm.Based on the state space model,the theory and calculation process of Kalman filtering and LQ control algorithm are analyzed,and the continuous form is transformed into discrete form.The objective function and constraint conditions of thrust distribution are established,and the complex method is selected as the thrust allocation algorithm.A set of numerical simulation programs for dynamic positioning pipe-laying ship are developed by C language.The accuracy and applicability of the programs are verified by comparing the results of time-domain simulation with those of Simo.Using the C program,the time domain simulations of pipe laying and non-laying operating mode of the dynamic positioning ship in multiple environmental conditions are calculated.The simulation contents include: wind loading,current loading,1st order and 2nd order wave force,pipe force,ship motions,controlling command based on LQG algorithm,thrust distribution based on complex method.In this paper,based on the static and dynamic analysis,a dynamic positioning capability evaluation C program is developed.The dynamic positioning capability curves of the pipe-laying and non-laying are calculated.Many time domain simulations combined with engineering requirements are carried out,and operation capacity curves of dynamic positioning for pipe-laying and non-laying are obtained.