Elimination of thermal instability in precise positioning of Galfenol actuators

Abstract

This paper presents a new method to eliminate deviation in positioning caused by coil's heat generation in magnetostrictive actuators. The advantages of the proposed system are compactness, high controllability and high reliability. The actuator package consists of Galfenol as active element and a magnification mechanism combined with a Peltier element or thermoelectric cooler (TEC). By using the temperature sensor, a thermoelectric cooler (TEC) is activated to reduce the temperature of the coil. However, the reduction of temperature by TEC alone is not enough to eliminate the error and controlling of applied voltage is also required. A simple PI controller for coil's current is combined with TEC and by reducing the temperature and current simultaneously, the positioning error is vanished completely.

Assessment of Capacitor-based Charge Estimators for Piezoelectric Actuators

“…Different actuators have been used for nano/micropositioning e.g. worm gears [8], magnetostrictive actuators [9] and linear motors [10]. Amongst all, piezoelectric actuators are the least bulky and the most precise ones [11].…”