Stepping Piezo Actuators - CEDRAT TECHNOLOGIES - #1

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Stepping Piezo Actuators Objective Stepping Piezoelectric Actuators (SPA) are new long-stroke linear piezoelectric motors for micro/nano positioning applications benefiting of the APA® heritage. They operate by accumulation of small steps. Between each step the actuator is locked in position. When the long stroke is performed, it can be also operated in a deformation mode for a fine adjustment. In this case, the stroke is proportional to the applied voltage, which leads to a nanometer resolution and a high bandwidth. This actuator can be supplied with CEDRAT TECHNOLOGIES standard Linear Amplifiers. In summary, SPAs offer: • A blocking at rest in any position (locking without power supply), • A high stiffness, • A nano positioning resolution all along the stroke • Non magnetic behavior Structure & operation modes The SPA relies on few parts : • The well-established Amplified Piezoelectric Actuators (see APA® data at www.cedrat.com), • A front mass, a clamp and a rod. Displacement of the Mass • Long stroke stepping Mode M1 (mm): Series of steps • Short stroke deformation Mode M2 (ìm): (Rod standstill. Actuator moves) • M2a: quasi-static • M2b : dynamic. One step of the SPA inertial motor One step realized by two operations : • Slow contract: Mass moves. Rod standstill • Fast expand: Mass standstill. Rod moves The principle of operation is described below: The long stroke stepping Mode M1 is produced by step accumulation with an appropriate 0-150V saw tooth voltage. The short stroke deformation Mode M2 is produced by deformation of the APA®, which is simply proportional to the excitation voltage between –20 to +150V. SPA can be driven by CEDRAT TECHNOLOGIES lab linear amplifiers such as the LA75 family, ordered by a signal generator, or by specific electronics. Only one channel per SPA is required. Different position sensors can be implemented for closed loop operations thanks to UC75 numerical controller. Please ask CEDRAT TECHNOLOGIES for further details about electronics and signals. All standard APAs® from CEDRAT TECHNOLOGIES can be operated as a SPA with appropriate add parts. Therefore the SPA concept can be considered as a way to expand the limited stroke of the APA®. However smaller APAs® (series ìXS, XXS, S, SM, M) are of higher interest, because they allow to realize very small flat piezo motors. Non magnetic actuators APAs® (NM option) can be selected for non magnetic actuation. Temperature range is typically –40°C to +80°C, but it can be extended to cryogenic (77K) or warm (140°C) temperatures upon request (HT option). View of the APA ìXS (m = 0.15gr). Micronora Award 2008