Characterization of three-dimensional dynamics of piezo-stack actuators

This paper presents a methodology for the characterization of dynamic behavior of piezoelectric-stack actuators. Piezo-stack actuators are used in many fields to obtain high-accuracy displacements and vibrations, commonly in multiple dimensions. However, obtaining accurate motions from piezo-stack actuators require thorough characterization of their non-linear dynamic response characteristics in three dimensions. In this work, a laser Doppler vibrometer-based precision characterization system is created to measure the three-dimensional dynamic motions of the piezo-stack actuators within a wide frequency range. A measurement reference frame is obtained by arranging three laser beams in a mutually orthogonal configuration. A set of stepped-sine tests are conducted at different levels of excitation amplitudes by individually exciting each of the stacks (of a multi-stack piezo actuator) and measuring the three-dimensional response in the measurement reference frame. The resulting dynamic response is decomposed into its components that occur at harmonics and non-harmonics of the excitation frequency. A power analysis is then conducted to determine the amount of contribution of each response component (harmonic or non-harmonic) in the overall response. The response behavior is then represented using a new approach constructed by extending the conventional frequency response function (FRF) description to higher-harmonic and non-harmonic components. The application of the approach is demonstrated by testing two three-axis piezo-stack actuators.

► Characterization of the three-dimensional dynamic motions of piezo-stack actuators.
► LDV-based three-dimensional measurement system is constructed.
► Stepped-sine testing to obtain wide-band response characteristics.
► Response components at harmonics and non-harmonics of the excitation frequency.
► An extended FRF definition to represent each response component.