Robust Observers And Controllers For Marine Surface Vessels Undergoing Maneuvering And Course-Keeping Tasks

ROBUST OBSERVERS AND CONTROLLERS FOR MARINE SURFACE VESSELSUNDERGOING MANEUVERING AND COURSE-KEEPING TASKS byNASSIM SAADDINE KHALEDAugust 2010Advisor: Prof. Nabil G. ChalhoubMajor: Mechanical EngineeringDegree: Doctor of Philosophy The dynamic behavior of marine surface vessels is highly nonlinear. Moreover, itis significantly influenced by environmental disturbances induced by winds, random seawaves and currents. The focus of this work is to develop an integrated guidance andcontrol system that enables under-actuated marine surface vessels to operateautonomously and yield robust tracking performance in spite of significant externaldisturbances and modeling imprecision.A nonlinear model for a marine surface vessel is developed to serve as a test bedfor assessing the performance of the proposed guidance and control systems. Themodel incorporates recent developments in ship modeling. Its formulation considers theeffects of coriolis and centripetal accelerations, wave excitations, retardation forces,nonlinear restoring forces, wind and sea-current loads, linear damping terms, and thecontrol force and moment. Moreover, it captures the dynamics of the rudder andaccounts for the physical limitations of both the rudder and the ship propulsion system.