Research On Pipelay Trajectory Tracking Control Algorithm For Dynamic Positioning Vessel

With the increasing attention paid on the ocean resource,the special equipment of the ocean engineering and the control technology are significantly hot point of the researchers recently.Dynamic positioning is a kind of positioning technology equipped on the oceanic equipment without external force resource.The environment disturbance can be measured by the measurement system,which can be compensated by the trust system and the control command is calculated by the control system to make the ship positioning or tracking trajectories precisely.Pipelay,cablelay and lift operation etc.need to be coordinated by dynamic positioning systems.Pipelay operation is an important method on oceanic resource transportation,whose key problem is to guarantee the tracking precision.Different control strategies are offered in this paper with the control methods are studied in this paper,and the effects of the controllers are discussed according to the simualtions.Firstly,a reasonable kinematics combined with the dynamic model of the DP ship together with the environment disturbance model should be built for the pipelay operation.And the same time,a model of pipe force caused by the submerged pipes should be modeled in the three horizontal freedoms,which should be tested by simulations.The relationship between the pipes' trajectory and the ship's during pipelaying needs to be discussed according to the analysis of the procedure of the operation.The uncertain of the system's parameters should be studied and a back-stepping sliding mode controller is designed for the trajectory tracking during pipelay operation.Based on the results received,changing the structure of the controller by involving the neural network.The adapt law of the neural network is designed and an adaptive neural network sliding mode controller is presented,whose stability is proved by the choosing a suitable Lyapunov function.The robustness of the system is improved and the controller tends to be applied in the actual engineering.The uncertain of the unknown propellers' saturation of the system during operation is considered and a sliding mode observer is offered,based on which a sliding mode controller is presented.The stability of the system is proved and a simulation is completed to show the superiority of the controller obtained.