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In 2005, the Italian Navy decided to investigate on potential benefits of using full-electric actuators in substitution of conventional hydraulic motors for equipments on board ship such as rudders, fins, winches, etc. The new actuators had to guarantee the required dynamic performances, i.e. very high torques/forces at very low speeds, besides high affordability and redundancy. For this purpose, in 2006 the Italian Navy committed a research project to the University of Rome-Sapienza, aimed to define innovative solutions and their convenience. This paper shows both scopes and development of the research activity which consisted of a) data collection of existing onboard oil-powered plants, b) study of operating cycles, efficiencies, maintenance burden, and possible improvements, c) design of suitable full-electric alternatives, d) detailed design of a high-thrust permanent-magnet linear actuator for direct-drive of rudder and fin steering gears. The proposed actuator will be verified by tests on a reduced-scale laboratory prototype in the final steps of the research program. [ABSTRACT FROM PUBLISHER]

The Italian Navy committed in 2006 to the Department of Astronautics, Electrical, and Energy Engineering-University of Rome “Sapienza” a Research Program aimed to define an automated procedure for air-gap monitoring of onboard generators. An effective solution was needed to overcome the heavy shortcomings of usual manual measurement practices. This paper describes the research work which led to very reliable rotor eccentricity indicators, based on measurement of internal currents in armature windings with parallel connections. The new approach permits absolute on-line estimations of both static and dynamic rotor shaft misalignments. A fully operative demonstrative system has been developed in the Department's laboratory. A four pole 17kVA generator was used for experiments, with artificial eccentricities produced by an apposite mechanical flange. A virtual instrument was used for data acquisition and processing, so obtaining a real-time estimation of the actual shaft misalignment. Comparison of data obtained from simulations and tests prove the reliability of the proposed methodology. [ABSTRACT FROM PUBLISHER]