AN ASSESSMENT OF FUZZY-LOGIC VESSEL PATH CONTROL

A fuzzy logic controller for ship path control in restricted waters is developed and evaluated, The controller uses inputs of heading, yaw r ate, and lateral offset from the nominal track to produce a commanded rudder angle, Input variable fuzzification, fuzzy associative memory r ules, and output set defuzzification are described, Two maneuvering si tuations are evaluated: track keeping along a specified path where lin earized regulator control is valid; and larger maneuvers onto a specif ied path where nonlinear modeling and control are required, For the tr ack keeping assessment, the controller is benchmarked against a conven tional Linear Quadratic Gaussian (LQG) optimal controller and Kalman f ilter control system, The Kalman filter is used to produce the input s tate variable estimates for the fuzzy controller as well, An initial s tartup transient and regulator control performance with an external hy drodynamic disturbance are evaluated using linear model simulations of a crude oh tanker, A fully nonlinear maneuvering model for a smaller product tanker is used to assess the larger maneuvers, The fuzzy contr oller exhibits promising performance and application flexibility.