Hydrodynamic parameter estimation of an open frame unmanned underwater vehicle

A semi-autonomous unmanned underwater vehicle (UUV), named VSOR, is being developed at the Laboratory of Sensors and Actuators at the University of Sao Paulo. The vehicle has been designed to provide inspection and intervention capabilities in specific missions in deep water oil fields. This work presents a methodology to identify the drag coefficients and virtual mass/inertia of an open-frame underwater vehicle using the system identification approach. Trials with the vehicle in a test tank have been performed. Using the vehicle onboard sensor information, the methodology is based on the utilisation of an uncoupled 1-DOF (degree of freedom) dynamic system equation of an underwater vehicle and the application of the integral method, which is the classical least squares algorithm, applied to the integral form of the system dynamic equations. An assessment of the feasibility of the method is presented.