Ship Motion Control Design In The Presece Of Input Saturation

In the late1980s and early1990s, backstepping design method as a recursive design method is put forward, which is the most effective method to solve the nonlinear system control problem. To facilitate the expression and analysis, the backstepping design method and Lyapunov stability theory are introduced firstly.In this thesis, a robust adaptive controller is designed for a class of nonlinear uncertain system with input saturation non-smooth nonlinearity, parametric uncertainty and unknown external disturbance. Hyperbolic tangent function is used to approximate the non-smooth saturation nonlinearity. The proposed controller can guarantee all the signals in the closed-loop system are bounded and the tracking error can be made global uniform ultimate bounded.And then, the proposed method is applied to the ship course-keeping control system with non-smooth input saturation nonlinearity. Simulation results indicate that the tracking error can be made arbitrarily small when ship tracks the set-point course and all the signals in the closed-loop system are bounded.