Research On Path Following Control Algorithm For Pipelaying Vessel

As the oil and gas exploitation increase, and the pipe is the main transporting approach,there are more pipes layed in the deep waters. The pipelaying vessel is a significant platformto lay the pipes on the seabed. Today, most of the pipelaying vessels are equipped with thedynamic positioning system (DPS). The vessel lays the pipeline along a pre-specifiedreference path through the active control of the vessel, as well as guarantees the structuralintegrity of the pipe at all times and completes other operations. Research on path followingfor pipelaying vessel can improve the efficiency of the operation and economy, reduce the risk.The primary research are as follows：Firstly, based on some reasonable assumptions, a3-DOF maneuvering motion model ofpipelaying vessel has been established, which is made up of the kinematic part and dynamicpart. Meanwhile, the models of the environment disturbance, such as wind, wave and current,and the model of the pipes are also proposed by the natural catenary.Secondly, according to the character of the pipelaying vessel’s operation, the pathfollowing is divided into two kinds, which includes path following with the pipelaying andpath following without the pipelaying. Low speed strategy based on LOS is applied to thetrack with pipelaying operation; high speed strategy is applied to the track without pipelayingoperation. During the operation of the welding, abandoning pipes and son, the function of thestop on track is applied to control the vessel’s position.Thirdly, the path following controller is designed with the direct model referenceadaptive control(DMRAC) algorithm which does not rely on the exact mathematical model，can adjust the parameter of the controller and make the system achieve the optimalperformance. As applying DMRAC, it has to requrie the system is almost strictly positive real.However, the vessel model does not satisfy the condition. This paper introduces the approachof the parallel compensation to slove the problem.Fourthly, the acceleration feedback is applied to the positioning controller, whichcontrols the vessel’s acceleration and improves the ability of the anti-jamming.In the end, computer simulation is applied to confirm the proposed path followingstrategy. The results shows the pipelaying vessel can lay the pipelines along the reference path,stop on the track，and can move to the destination fastly from the port to the operating area..The proposed approach for path following can accomplish the control of path following,meet the demand of the pipelaying operation, and are valuable to the further theoreticalresearch as well as engineering applications of the pipelaying vessels.