Unneland, Kari (Norwegian Univ. of Science and Tech.), Egeland, Olav (Norwegian Univ. of Science and Tech.)

Positive Real Modeling of Ships for Dynamic Positioning

Scheduled for presentation during the Mini-Symposium "Dimension reduction of large-scale systems II" (ThP03), Thursday, July 27, 2006, 16:35−17:00, Room C2

17th International Symposium on Mathematical Theory of Networks and Systems, July 24-28, 2006, Kyoto, Japan

This information is tentative and subject to change. Compiled on May 19, 2024

Abstract

In this paper the positive real modeling of a horizontal 3 degrees of freedom (surge, sway and yaw) ship model for dynamic positioning is described, where the main focus is on the modeling of the radiation forces. The radiation forces and moments in the equations of motion for a seagoing vessel describes the interaction of the moving ship with the surrounding fluid. The radiation forces and moments are an important part of the ship model, and efficient statespace formulations are recalled to represent these forces. This representation is of interest in design of marine control systems and in real-time simulators of marine systems. The passivity properties of the radiation forces and moments and the overall ship system is investigated, and the properties are kept when representing the radiation forces and moments in state-space form. The state-space models are of high order and it is necessary to use model order reduction techniques to make them efficient for computer simulation and control synthesis. Finally, different model order reduction procedures are applied with the aim of keeping the passivity properties of the model.