An Overview of Piezoelectric Self-Sensing Actuation for Nanopositioning Applications: Electrical Circuits, Displacement, and Force Estimation

Abstract

The industrial sector often employs piezoelectric materials as actuators for a variety of uses, some of which requires a precise positioning while being limited by space and cost factors that impede the insertion of external position and force sensors. Piezoelectric Actuators are characterized by strong nonlinearities (hysteresis and creep), badly damped oscillations and sensitivity to the environment, especially temperature variation, that make the measurement of the position mandatory to guarantee the required precision and repeatability of piezoelectricbased positioning systems operating at the micro and nanoscale. Self-Sensing Actuation techniques allow the implementation of precise positioning control of Piezoelectric Actuators without the hindrance of external position sensors. This paper reviews the different Self-Sensing Actuation techniques used for precise positioning control of Piezoelectric Actuators. The principle of Self-Sensing Actuation is defined by the capability of deriving the physical state of a Piezoelectric Actuator (displacement, perceived force, ¤ ¤ ¤) without the use of external sensors to directly measure thereof, but rather by estimating it from the measurement of less intrusive and cheaper physical signals produced by the Piezoelectric Actuator itself (throughout current, voltage drop, ¤ ¤ ¤). The applicability and constraints of each Self-Sensing Actuation approach are examined in order to help in the determination of the most adequate approach for precise control of Piezoelectric Actuators positioning and handling force control.

High-Performance Tracking for Piezoelectric Actuators Using Super-Twisting Algorithm Based on Artificial Neural Networks

“…The mechanics of the hysteresis curve of the PEA employed is shown in Figure 3, which was produced by using 2 triangle cycles with the previously described features where the maximum hysteresis achieved was 4.47 µm at 37.7 V. The sequence starts at the initial point ( 1) which is also known as the initial point since it is where the PEA undertakes its operation; thus, a first ascending curve climbs until (2), which is the upper target point at the maximum voltage (145 VCC). Thereafter, the fall is through an asymmetric path along the first descending curve until (3), the lower converging point.…”

“…In the early 1970s, the high accuracy positioning was constrained only at academic domains; however, as a result of advanced fabrication methods, the beginning of the current century leads the possibility of bringing micro-actuators in industrial environments [1]. Piezoelectric actuators (PEAs) are suitable candidates when there is an application that needs for nano-microdisplacement combined with precision as requirements [2]. Additionally, these systems provide accuracy and mechanical capabilities due to their high stiffness [3].…”

Accuracy in Force Estimation Applied on a Piezoelectric Fine Positioning System for Machine Tools

“…The principle known as self-sensing describes the ability of piezoelectric actuators to determine physical states such as deflection xpiezo or applied force Fpiezo without use of external sensors [8]. Values are determined by using signals, which are generated by the piezoelectric actuator itself and can be measured with relatively little effort.…”

“…There are different approaches for "self-sensing" that use either the piezoelectric effect or the changes in electrical properties of the actuators [8]. The use of the piezoelectric effect is based on the reversible correlation between an applied force Fpiezo and the generation of an electric field E caused by electrical charges q.…”

“…The electric charge q is determined by measuring incoming and outgoing currents I. Since the applied voltage Upiezo itself induces electrical charges qind, evaluation electronics are necessary to separate the self-induced electric charge qind from the applied electric charge q [8].…”