Active disturbance rejection control of ship course keeping based on nonlinear feedback and ZOH component

Abstract

To solve the problems of external disturbance, internal model uncertainty and rudder angle energy input to much in ship course keeping, an active disturbance rejection control algorithm based on nonlinear feedback is proposed. Firstly, the ADRC algorithm is designed to control the ship course, and the external disturbance and internal uncertainty are estimated by the linear state observer, and then the controller is compensated. In the process of navigation, “large rudder angle” and “high rudder frequency” will increase ship roll and rudder wear. Nonlinear feedback is used to modify the error to reduce the excessive input of rudder angle energy. Zero order holder is introduced to reduce rudder frequency and rudder wear. Finally, the simulation results show that the controller has well tracking effect. The nonlinear feedback with ZOH has smaller rudder angle and frequency. In severe sea state, high rudder frequency and high rudder amplitude will cause the wear of ship steering gear, excessive heeling and reduced stability, so the algorithm proposed in this paper is more secure and energy-saving.