Alexander Murphy

Identification of a Marine Vessel's Hydrodynamic Parameters

December 11, 1998
1:00 PM
29 Cullinane Hall

Abstract

This thesis applies techniques of system identification (SI) to a marine vessel, moving in the surge direction (straight ahead, rudder centered). The goal of identification is to estimate the hydrodynamic parameters of a vessel, such as the hull drag resistance, thrust deduction factor, and wake fraction. The SI techniques are applied to a mathematical model for the surge equation of motion and utilize measurements of shaft rpm, propeller pitch, and the vessel's speed through the water. It is shown that by assuming a model for the hydrodynamic parameters that vary as a nonlinear function of the vessel velocity and using numerically robust algorithms, improved convergence and tracking may be achieved. Several methods are proposed for SI and their advantages and disadvantages are discussed. To demonstrate the feasibility of this research, the proposed SI techniques are applied to data measured from the vessel Exxon Philadelphia.

Thesis Committee:
Prof. Brad Lehman (advisor)
Prof. Bahram Shafai
Prof. Gilead Tadmor