Modelling and Identification of Yaw Motion of an Open-frame Underwater Robot

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. With the aim of identifying the hydrodynamic motion parameters, such as, drag coefficient and added mass inertia, experimental trials with the vehicle prototype in a test tank have been performed. 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