White paper: the ultrasonic piezo drive for high-accuracy positioning
Cedrat Technologies S.Acontact supplier
‘The ultrasonic piezo drive: an innovative solution for high-accuracy positioning’
Piezo-electric motors have been successfully developed for various applications such as autofocus drives in camera lenses and handling equipment for semiconductor production. Their high speed and accurate positioning capability, combined with a favourable holding torque in unpowered condition, make piezo motors also very attractive for actuation purposes in spacecraft mechanisms. However, so far only a few studies have been reported considering their suitability for actual use in space. Piezo motors use a combination of piezo-electric and friction forces to generate a progressive motion of an output element. This white paper from Cedrat Technologies introduces a new concept of a versatile piezo motor driven at ultrasonic frequency, and it elaborates on a number of space-related issues such as the compatibility with the relevant mechanical and thermal environment. Furthermore, the possible implementation in different space mechanisms is discussed, with specific focus on miniaturised equipment as needed for small satellites.
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Cedrat Technologies owns the patented Amplified Piezoelectric Actuator (APA) technology. APA integrates an amplification mechanism and offers larger strokes than conventional piezoelectric actuators.
Cedrat Technologies designs two main types of actuators suitable for astronomical instrumentation: parallel pre-stressed actuators and amplified piezo actuators.
A mechanical structure based on serial stacking of level arm has been designed in order to amplify the ingoing force of the harvester system. The outgoing force is applied on the smart material. The deformation of the mechanical structure is based on flexural pivots using four truncated circular collars. The last amplification is based on the amplified piezoelectric actuator (APA) shell from Cedrat Technologies.
Stepping piezoelectric actuators based on the stick-slip effect inherently make use of a friction contact between stator and rotor. This contact defines the actuator’s performance but is prone to wear and tear. For broad use, the actuator has to be able to perform around one million strokes. To assess the actuator’s performance in terms of force, speed, mechanical output, electrical input and long-term stability under different load and environmental conditions, as well as different ...
According to Cedrat Technologies, future aeronautics are more likely to use electric actuators than hydraulic actuators. Existing amplified piezo actuators (APAs) with steel shells are good candidates. Lighter carbon shells are being developed to further increase their efficiency. For helicopter rotor blade applications this evolution is almost unavoidable, but it is also very interesting for other domains.