Nonlinear Thrust Controller for Marine Propellers in Four-Quadrant Operations

In this paper a nonlinear thrust controller for a marine propeller in four-quadrant operations is presented. It is a shaft speed controller where the desired velocity is computed based on the desired propeller thrust and on the torque losses, estimated with a nonlinear observer. Experimental results are provided to demonstrate the effectiveness of the controller. The proposed scheme shows improved performance in thrust production when compared to traditional shaft speed and torque control.