Abstract
A linear actuator controlled by the reversed-phase connection of two piezoelectric bimorphs is proposed in this study to solve the problem of drawback in the existing piezoelectric linear actuators. The actuator is driven by one excitation signal, the two piezoelectric bimorphs will always bend in opposite directions by the reversed-phase connection, so the directions of the force output by the two piezoelectric bimorphs are opposite. Because of the length difference of the clamping blocks, the two forces outputted by each bending is different in magnitude, and always have a resultant force in the same direction to make the actuator move forward two steps in one cycle without drawback. A series of experiments were conducted to evaluate the performance of the actuator provided. The starting voltage is 40 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{V}_{\mathrm {p-p}}$ </tex-math></inline-formula> , resolution can reach <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.16~\mu \text{m}$ </tex-math></inline-formula> without load. The load capacity of the actuator is 450 g with a 100 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{V}_{\mathrm {p-p}}$ </tex-math></inline-formula> voltage, a 2-Hz frequency, and the average step displacement in this case is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.725~\mu \text{m}$ </tex-math></inline-formula> . The prototype has high linearity and good repeatability. Experiments have proved that the actuator controlled by reversed-phase connection can eliminate drawback in principle, and can move forward two steps in one cycle. The resolution of the prototype by the reversed-phase connection is much higher than the in-phase connection, and it is a new method to improve the driving performance of piezoelectric actuators.
Highlights
In recent years, inertial piezoelectric actuators have been widely used in robots [1]-[3], biological engineering [4]-[6], optics [7]-[9], and ultra-precision machining [10]-[12] fields because of their simple structure, large stroke and high precision.Inertial piezoelectric actuators can be divided into signalcontrol type (SCT), mechanical-control type (MCT) and friction-control type (FCT) according to the control method
Aiming for a universal way of drawback control, this paper present a piezoelectric linear actuator controlled by the reversed-phase connection of two bimorphs
In order to better understand the influence of bimorph connections, the output stepping characteristics of in-phase connection, reversed-phase connection and single bimorph were tested under the frequency of 2 Hz and the voltage of 40
Summary
Inertial piezoelectric actuators have been widely used in robots [1]-[3], biological engineering [4]-[6], optics [7]-[9], and ultra-precision machining [10]-[12] fields because of their simple structure, large stroke and high precision. Wang et al proposed an inertial piezoelectric actuator that used magnetorheological fluid to adjust friction, achieving the goal of no drawback, the prototype resolution reached 0.0204 μm [33]. This type of actuator requires complex control signals, and the performance of the smart material itself needs to be studied. Two bimorphs of the actuator are asymmetrically clamped and connected in reversed-phase, so that the actuator always receives net force in the same direction This method eliminates the backward phenomenon in principle, so there will be no backward under any frequency and voltage
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