Numerical simulation for ship manoeuvring and path following in level ice

Abstract

This thesis provides a method that combines numerical detection and semi-empirical formulas to solve the ship-level ice interaction in time domain which can be applied to studying ship manoeuvring and autopilot in level ice. Numerical implementation has been accomplished by using programming language FORTRAN90 under Linux Operation System. The ship-ice interaction and the ice breaking process is simulated by adopting a 2-D Discrete Element Method (DEM). A new detection technique name Polygon-Point Algorithm is developed to identify the contact area. Different Pressure-Area (P-A) relation and flexural ice plate model are included and studied. Full 3DOF ice induced load is derived in this thesis. The method is validated by using the data from two model ship tests and one full scale sea trial. A Line-of-Sight (LOS) guidance system and PID controllers for path following and velocity maintaining are also developed. Detail has been provided in solving discontinuity of commanded heading angle. The path following ability has been examined and presented. Recommendations for future works is also provided in the thesis.