Model identification for impact dynamics of a piezoelectric microactuator

A parameterized model for the impact dynamics of a piezoelectric microactuator is proposed, and a system-identification procedure for quantifying model parameters is presented. The proposed model incorporates squeeze-film damping, adhesion and coefficient-of-restitution effects. Following parameter quantification from sample data of bouncing impacts and progressive ramped-square-wave inputs, the model is found to be effective in predicting the time response of the actuator to a range of square-wave and sinusoidal inputs. The main contributions of this paper are to show that the dynamic response to micro-scale contact can be predicted using simple lumped-parameter modeling after a proposed system-identification procedure is performed and that certain small-scale forces can be quantified. For example, for motions where bounce of the cantilever tip may occur, the range of adhesion is found to be time dependent and vary between approximately 20 and 520 nN, while the range of squeeze-film damping is estimated to be between 50 and 130 nN, depending on the input signal frequency and amplitude. The presence, absence and quantity of bounces upon impact are predicted very accurately, while oscillation amplitudes and contact durations are predicted to be between 1% and 30% error for the majority of many test cases of periodic inputs between 5 and 100 Hz.