Movement control of a variable mass underwater vehicle based on multiple-modeling approach

This paper is one of the few studies dealing with modeling and control of a variable mass underwater vehicle with six degrees of freedom. Since, the mass of fuel changes during the operation, both mass and the center of mass of the vehicle change with time. Therefore, dynamic equations are written around the center of buoyancy and these equations are more complicated than the equations of the fixed mass underwater vehicles. Also, fin angles which are means of path-following (control inputs) do not directly appear in the dynamical equations which cause more complexity in the controller design. In this paper, the multiple-modeling approach is used in the controller design and the control signals are achieved by the weighed combination of multiple controllers. Simulation results reveal the effectiveness of the multiple controllers in set point tracking.