Research On Ship Dynamic Positioning Control Based On Sliding Mode Variable Structure

With the rapid development of exploitation and production in marine resources and energy, the positioning of floating structures becomes more and more attention. Dynamic Positioning System (DPS) is a closed-loop control system, which uses the ship thruster to resist wind, wave and flow environmental disturbance, and making the ship keep its position and heading within the prescribed scope of operation as much as possible. Its advantage is that ship’s position is not restricted by the depth of the water, and cost of ship positioning is lower in deep water.Dynamic positioning control technology has gone through three generations. The sliding mode variable structure control (SMC) has complete robustness when the uncertainty environment interference exist in the system. So this paper uses SMC to design the ship dynamic positioning controller, SMC usually cause chattering phenomenon, In order to weaken chattering, this paper makes the Adaptive control and sliding mode control combine to design ship dynamic positioning controller. The main research work includes the following aspects:Through describing ship dynamic positioning control problem, then designing the sliding mode controller and Adaptive sliding mode controller of 3 DOF motion model, and analyzing the stability of controller. In order to prove that the designed controller has good control performance and robust performance, taking a dynamic positioning ship as the research object to process the simulation and the result analysis for the designed controller. The simulation results show that the ship can overcome the external environmental disturbance to move and stability in the desired location, and verifying the good control performance and robust performance of the controller.