Comparison between mechanical displacement electroceramic systems:: Piezoelectric motors and actuators

Piezoelectric motors can be classified as resonant or forced response motors. As to resonant motors, travelling wave motors, either rotary or lineal must be highlighted. These devices have several features that make them different as compared to any other type of piezoelectric devices. In general, they are comparatively more complex since they include intermittent contact problems between solids, synchronized oscillations in perpendicular axes, and excitation close to the resonance. All these features have limited the application of this kind of actuators, even though some functional characteristics, as noiseless operation, high torque range and their compact construction have made them suitable for several applications. On the other hand, piezoelectric actuators with forced excitation, due to their non-existence movement amplification in the resonance, have been used in applications where an ultra-accurate positioning is required with intermediate levels of force. Lineal multilayer and cyclic actuators must be identified as classical forced actuators. The aim of this paper is to summarize, analyzing the main features of the resonant and forced actuators, the applications where this type of motors will be used in the future. With the intention of remark the steps needed to achieve the commercial application, past and nowadays most important researching lines will be studied and a possible evolution in the future will be pointed out.