The Research Of Dynamic Positioning System Control Algorithm For Pipelaying Vessel

Pipelaying vessel(PV) required low-speed sailing, and during forward process kept theheading and the predefined track consistent while laying pipelines at sea, all these functionsshould guaranteed by a good performance Dynamic Positioning system. Ship DynamicPositioning technology (Dynamic Positioning, DP) without the aid of the mooring system,make the ship to use its own propulsion device to withstand wind, waves and currents, andother external disturbances, maintained a certain attitude in a target position in the sea, or toaccurately track the trajectory of a set for the completion of a variety of complex operationsat sea.This issue is a major technology achievement conversion project of Jiangsu province;here have a research on Dynamic Positioning or Tracking system controller design,combined with the application of actual project based on S-lay vessel. Towards theautomatic mode of Dynamic Positioning, constructed the DP low frequency model for PVwhile the speed of the hull near to zero. During the station keeping process, considered theacting force problem of pipe to PV and constructed the force model, employed syntheticgradual expansion method of singular perturbation strategy to solve the governing equation.For the DT-navigation model, established the DT low frequency motion model, analyzedthe hull resistance and the pipe drag force which generated by the process while operating,also established the calculation model. Meantime, in order to for engineering applications,the model of wind, wave and current and other environmental interference were constructed.Towards DT part for PV, the control process is a typical control through the line, takinginto account the track small difference, used conventional tracking control strategy. As thePID control algorithm is still widely used in ship control systems, and is suitable forlow-frequency motion control, controlled the heading while navigating, here used the PIDalgorithm as the main control algorithm. Moreover, compiles the program under thecircumstance of MATLAB to see the effect of the corresponding controller. Simulationresults show that the conventional track strategy combined with PID control algorithm isable to get a good system dynamic performance which important is the ability to improveoperational precision with the actual value of the works.Towards DP part for PV, combined with the practical application, based on thepipelaying vessel is difficult to establish accurate mathematical model, nonlinear, big lag etc., using fuzzy PID control algorithm, through the fuzzy control rules online self-tuningPID parameters; according to the ship model mismatch characteristics, using PID-DMCcontrol algorithm, the conventional Dynamic Matrix Control(DMC) algorithm byintroducing the PID link, to realize the effective control of the system. According to thecontrol thinking of the surge, sway, heading three degrees of freedom for decouplinganalysis, combined with PV dynamic position system constraints, independent controller aredesigned, in the case of no wind hydrostatic simulation. The simulation results show that theFuzzy self-tuning PID parameters online controller and DMC controller with PID correctionlink design scheme is feasible, and can achieve effective positioning effect, under thecontrol effect of comparative analysis, Fuzzy PID algorithm is better than PID-DMCalgorithm, but PID-DMC algorithm is more in line with the requirements of the actualoperating condition requirements.