Trajectory control and optimization of supercavitating torpedo

Underwater flight is greatly limited by the max speed of about 40 m/s that can be attained by the torpedo because of skin friction drag. Supercavitating torpedo can break the speed barrier and attain higher speed. But supercavitating phenomenon has its drawbacks which present challenges in modeling and control a supercavitating torpedo. Firstly, in this thesis, modeling and designing a controller to maneuver of a supercavitating torpedo is presented. The controller was obtained by LQR synthesis based on the assumption that cavity is fixed and the torpedo is situated symmetrically in cavity. The primary goals of controller were to get aggressive maneuverability and maximizing steady flight performance. Then optimal control problem of flight trajectory was discussed which yielded the control time histories that maneuver the torpedo according to a time-fuel optimal strategy. It was solved using the direct transcription method, a solution of a discrete parameter optimization problem. Finally the numerical simulations examples and resulting trajectories were performed to demonstrate the effectiveness of the proposed methodology.