Model-Based Piezoelectric Self-Sensing Technique

Abstract

Piezoelectric self-sensing allows the measurement of frequency response functions of dynamical systems with one single piezoelectric element. This piezoceramics is used as actuator and sensor simultaneously. In this study, the frequency response functions are obtained by measuring the current flowing through the piezoelectric element, while it is driven by a harmonic voltage signal with constant amplitude. The current flow is composed of the part which is required to drive the piezoelectric element as an actuator and a second part which is the sensor signal that is proportional to the vibration amplitude of the attached mechanical system. Especially for low electromechanical coupling the first part is dominant and the influence of the mechanical system is only marginal. With an idealized mathematical model of the piezoelectric element, the admittance can be calculated and the actuator current can be eliminated from the measured signal. This software-based solution does not require any additional electrical circuits or precise tuning during the measurements. The influence of errors of the parameters for the piezoelectric model on the recalculated signals are shown, which helps to improve the estimations. Alternatively, they can be obtained by additional measurements. The proposed technique is demonstrated on a clamped beam with attached piezoelectric element.