Research On Path Following Control Method Of Working Pipe-laying Vessel

With the development of the world economy, more and more fuel such as oil and gas arerequired. While the fuel resource in land can’t satisfy the consumption, so many countriesspend a lot of monkey and force to research the new technique to exploit the fuel storing inthe beauty sea. The fuel in the sea is commonly via the pipe laying in the seabed to the land orthe storage station in the sea So the pipe is very important to utilize the resource in the sea.While the pipe-laying vessel which is an equipment to lay the pipe, attract lots of scientists toresearch the new methods to manipulate them.At first, the system model is built. With some reasonable supports, the6-DOF model ofthe vessel is simplified to the3-DOF model of a surface vessel. Based on the experientialformulas, the models of the disturbance such as wind, wave and current are set up. In order toguarantee the integrality of the pipeline, the Structure of the line is analyzed. Based on thecatenary theory, the pipeline model is well analyzed and educed. All those models are thebasements for the following steps to form a usefull controller.Then, the strategy of path following is well selected. Because of the great differencebetween the pipeline reference path and the reference trajectory of the vessel, the path of thevessel to follow is got from the geometry conversion of the pipe path. The motion controlsystem of the vessel is divided into three ranks, and every grade has its own function. Thecommon LOS(Line-Of-Sight) guidance arithmetic has very low convergence speed, so a newdynamic LOS arithmetic is designed. Using the discrete path following strategy and the newguidance arithmetic, the tactic of two working modes: path following and station keeping aredeveloped.At last, the trajectory tracking controller of sliding mode and adaptive sliding mode aredesigned respectively. Using the sliding mode controller (SMC) to dominate the pathfollowing of pipe-laying vessel can improve the robust of the system. The adaptive controllerhas better performance in dealing with the uncertainess of the system, but the robust of thecontroller is poor. So based on the combination of two methods, the adaptive sliding modecontroller (ASMC) is designed to track the desired path, and the new controller has theadvantages of both theories. The adaptive rate of variable can be gotten by the Lyapunovtheory. Using the saturation function instead of the signl function can reduce the chatter of thesystem. The boundary layer arithmetic is used to estimate the influence of the disturbance inthe adaptive sliding mode controller. The translation from an uncertain matrix to a variable using the unit matrix can simplify the controller.Based on the dynamic LOS arithmetic path following strategy, the SMC and the ASMCare simulated by using the Matlab platform. The results of the simulation reveal the ASMCcan reduce the chatter of the system, and get better performance. So the ASMC has referenceSignificance for following research and good application value in the project in the future.