Marine Propeller Thrust Estimation in Four-Quadrant Operations

This paper proposes a scheme for thrust estimation of a marine propeller over the full four-quadrant range of Propeller shaft speed and vessel speed. Based on Shaft speed and motor torque measurements, the scheme involves a nonlinear observer for the propeller torque that shows stability and robustness for bounded modeling and measurement errors. The propeller thrust is computed as a static function of the propeller torque. The performance has been demonstrated in e perimental tests.