Abstract
The motion control of a surface ship based on a four degrees of freedom (4-DoF) (surge, sway, roll, and yaw) maneuvering motion model is studied in this paper. A time-scale decomposition method is introduced to solve the path-following problem, implementing Rudder Roll Stabilization (RRS) at the same time. The control objectives are to let the ship to track a predefined curve path under environmental disturbances, and to reduce the roll motion at the same time. A singular perturbation method is used to decouple the whole system into two subsystems of different time scales: the slow path-following subsystem and the fast roll reduction subsystem. The coupling effect of the two subsystems is also considered in this framework of analysis. RRS control is only possible when there is the so-called bandwidth separation characteristic in the ship motion system, which requires a large bandwidth separation gap between the two subsystems. To avoid the slow subsystem being affected by the wave disturbances of high frequency and large system uncertainties, the L1 adaptive control is introduced in the slow subsystem, while a Proportion-Differentiation (PD) control law is adopted in the fast roll reduction subsystem. Simulation results show the effectiveness and robustness of the proposed control strategy.
Highlights
It is still widely used in the aerospace control community [32,33]. This time-scale decomposition technique was introduced to the ship motion control problem in the previous work [28]; the result was only limited to the Rudder Roll Stabilization (RRS) control in the course-keeping problem
The control law in the path-following subsystem is of great importance, because pathpath-following performance is primary the primary control objective in this study reducfollowing performance is the control objective in this study andand rollroll reduction tion performance can be regarded as the secondary objective
This nonlinear model is widely used as a benchmark model in the field of ship motion control to evaluate the performances of different control strategies
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The studies that were the basis for real implementations can be found in Källstrom [6], Van der Klugt [7], Van Amerongen et al [10], Blanke et al [9,18], Grimble et al [19], Lauvdal and Fossen [12], and Crossland [20], among others In these studies, the control objective was limited to RRS control in the course-keeping problem. A time-scale decomposition method is introduced to the RRS control system in the path-following problem, where the rudder is the only input for both the heading control and the roll reduction control. The time-scale analysis strategy offers a new analytical framework for considering the coupling effects of the 4-DoF ship motion system This technique is used to decouple the ship motion system into a subsystem of slow heading control and a subsystem of fast roll motion control.
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