Objectives To improve the performance of course tracking and reduce the course errors of an underactuated surface ship, a heading control method based on a finite-time extended state observer (FTESO) and sliding mode control algorithm is studied.
Methods A pre-filter is proposed to reduce the influence of the large rate of speed change when steering. The time-varying sideslip angle is estimated by FTESO, and course error is amended by the estimated sideslip angle in a timely manner. To simplify the design of the controller, external disturbance and internal uncertainty in the yaw direction are estimated by the observer simultaneously, and compensated for in the controller design. Considering input saturation, a sliding mode control law is designed by combining FTESO and a sliding mode surface with an integral term. The stability of the control system is proven by the Lyapunov theory.
Results The simulation results show that the proposed controller reduces course tracking error and makes it converge to zero in a shorter time.
Conclusions The results of this study can provide references for the course tracking control design of surface ships.
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