Course-keeping control for ships with nonlinear feedback and zero-order holder component

Abstract

Course keeping control is the core of automatic navigation for ships in marine transportation. To optimize the steering conditions of course-keeping controller and enhance its robustness in heavy sea states, a new nonlinear course-keeping control algorithm is designed with power function nonlinear feedback and ZOH model controller. Take the new generation of teaching-training vessel Yupeng from Dalian Maritime University as the research plant, and the nonlinear Nomoto ship model with a zero-order holder component is constructed to design the ZOH model controller. Then the deviation signal from the closed-loop system is modified by a power function nonlinear feedback component to reduce the control output. The stability of the closed-loop system is analyzed by the describing function method and Nyquist criterion. The simulation experiments in normal sea states and heavy sea states are respectively carried out to verify the control performance. The simulation experiments show that the performance of this nonlinear course-keeping control algorithm is satisfactory, which can still be effective in heavy sea states. The steering frequency is reduced significantly, and the steering condition of the controller meets the requirements of navigation practice. The nonlinear course-keeping control algorithm is more suitable for the navigation practice and engineering application.