Nonlinear Thrust Controller for Marine Propellers in Four-Quadrant Operations

Abstract

Abstract-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.

Preliminary Simulation Studies of a New Four-Quadrant Propeller Thrust Controller Applied to Underwater Vehicles

“…), the non-dimensional parameters advance number J and Reynolds number, the propeller submergence and environmental state (waves, currents, etc.). In order to be able to estimate the propeller torque loss, Q p is represented by the torque produced at zero advance speed, that is the propeller is deeply submerged and not subjected to losses, plus a term Δ q that incorporates the torque losses (Pivano et al 2007):…”

“…In this way the controller is able to compensate for the thrust loss. The mapping to compute the desired shaft speed in Pivano et al (2007) is improved. This is done in order to reduce the high control activity experienced in Pivano et al (2007) for values of the shaft speed and the vessel speed in the 2 nd and 4 th quadrants.…”

“…The mapping to compute the desired shaft speed in Pivano et al (2007) is improved. This is done in order to reduce the high control activity experienced in Pivano et al (2007) for values of the shaft speed and the vessel speed in the 2 nd and 4 th quadrants. A simulation study is performed in order to evaluate the performance of the vehicle when employing the proposed method compared to the conventional shaft speed and torque propeller controllers.…”

“…The precision and complexity of the required tasks need an increase of the maneuvering accuracy and the propulsion system plays a key role in the achievement of the missions. Thruster modeling and control has been subject to a growing interest in the last years (Yoerger et al 1990), (Healey et al 1995), (Whitcomb and Yoerger 1995), (Fossen and Blanke 2000), (Bachmayer et al 2000), (Smogeli 2006) and (Pivano et al 2007). The primary objective of low level thruster control is to obtain the desired thrust from the propeller regardless the environmental state.…”

“…In consequence, thrust control may be poor when thrust losses occur. In this paper a recently reported four-quadrant nonlinear thrust controller (Pivano et al 2007) is applied to underwater vehicles. The controller is designed for fixed pitch electrically driven propellers and controls the shaft speed.…”