Study on Displacement Self-Sensing of Piezoelectric Actuator

Abstract

This paper aims to make piezoelectric ceramic actuator self-sense its own displacement in the absence of independent sensor. It is derived from the basic piezoelectric equation that the free charge on the wafer of piezoelectric ceramic actuator contains displacement information. So a displacement self-sensing method based on integrate circuit is presented. Voltage driving circuit for the piezoelectric ceramic actuator and integrated circuit for gathering free charge are designed. Based on the proposed compound circuits, the actuator can sense its own displacement while actuation. It is convenient to adjust the circuit and easy to acquire sensitive signal by using this method, and the impedance mismatching problem met in bridge method is overcome. The experimental results show that piezoelectric self-sensing actuator can effectively measure its displacement signal under the conditions of different wave form of driving voltage and different driving voltage frequency.

Piezoelectric actuators with on-board sensing for micro-robotic applications

“…Position sensing methods for actuators that use off board sensors such as high speed cameras [20] or displacement sensors [21] are not appropriate for autonomous operation. Strain sensing in piezoelectric actuators has been proposed many times for example using electrical bridge circuits [22,23], charge/voltage feedback [24], and combinations of charge based and capacitance based position measurement [25]. Almost all these methods either have a restricted range of operational frequencies or require additional sensing electronics.…”

Concomitant sensing and actuation for piezoelectric microrobots

“…Despite the popularity of piezoelectric actuators in micro-positioning applications, a common limitation is nonlinearlity, hysteresis [23] and creep [24] in displacements especially under dynamic conditions. Of the numerous solutions proposed to overcome this issue, particularly appealing are ones that exploit the concept of self-sensing [25][26][27][28][29][30] of piezoelectric materials because they allow for miniaturization. Broadly, the methods for self-sensing fall into the category of voltage or current feedback [31], charge compensation [23,32], permittivity measurement [33,34], empirical modeling [35,36], or a combination [37,38].…”