Research On Robust Control Theory For Dynamic Ship Positioning

With the increasing demand for the development of the ocean, the amount of offshore operation has been massive increasing. Offshore operations are often required a stable operating platform, dynamic ship positioning with its own propulsion system to resist the interference of the external environment disturbance,so as to accomplish this task well. However,due to the change of the water dynamic parameters of the ship, the mechanism of the environmental disturbance is complex and has some randomness, which leads to the inevitable uncertainty in the establishment of the mathematical model, the robust control can take full account of the model uncertainty, and ensure the performance of the system, which is very suitable for the control of the dynamic ship positioning.In this paper, we mainly study the linear and nonlinear robust control theory, and apply it to a certain type of dynamic positioning ship.Firstly, the mathematical model of the ship is established, and the validity of the model is verified by simulation. The environmental disturbance of the wind, wave and current in the is analyzed, and the relevant mathematical model is established.Secondly, according to the two important methods of H∞ control μ synthesis for linear robust control, using mixed sensitivity optimization approach, combined with the characteristics of dynamic ship positioning, analyzes the system uncertainties, linear robust controller design, and through the simulation of two kinds of designed linear robust controller,proved its robustness.At last, using the Backstepping design, base on Lyapunov stability theory, transform the dynamic positioning ship problem into the form of L2 interference suppression problem,and through the simulation of the designed nonlinear robust controller, proved its robustness.