Stress self-sensing in Amplified Piezoelectric Actuators through a fully-coupled model of hysteresis

Piezoelectric actuators are among the most used devices for micro-positioning applications. Yet, their output displacement shows non-negligible hysteresis effects with respect to both the input voltage and the mechanical stress and, as a consequence, an accurate control system has to be designed, taking into account the mechanical stress measurement too. This task is usually addressed by exploiting external bulky force sensors, e.g. load cells. A novel stress self-sensing approach is proposed in this paper, which allows the stress estimation by simply exploiting the measurement of electrical voltage and current of the piezoelectric stacks. In particular, a thermodynamic consistent fully-coupled multi-input multi-output model of hysteresis is exploited. The method is applied for the first time to a commercial Amplified Piezoelectric Actuator with a crossbow-like amplification system. An experimental validation of the approach is proposed and discussed.