Type Piezoelectric Actuator Research Articles

A novel piezoelectric actuator with a screw-coupled stator and rotor for driving an aperture

Variable apertures have become very important in optical applications. This paper presents a new type of piezoelectric actuator with a screw-coupled stator and rotor that is developed to operate an aperture. The actuator and the aperture are integrated to control the luminous flux. To open or close, the aperture only needs to rotate through a limited angle. Therefore, the actuator is designed so that the rotor and the stator are simply connected by a screw to couple the axial preload and the circumferential movement. The torque and velocity of the actuator are produced by its circumferential motion. The preload of the actuator is applied by deforming the rotor along the axial direction. This method of preloading makes it difficult to keep the preload constant during the actuator’s work. To overcome this problem, a novel flexible rotor with a low stiffness is designed. An equivalent stiffness model of the rotor is presented for the design of a flexible rotor. Its design parameters are determined by a numerical model and confirmed using the finite element method. A prototype is fabricated to drive the aperture. The experimental results demonstrate a resolution of 20 μrad and a rotational range of 300°. The opening and closing durations of the aperture are 96 ms and 97.2 ms, respectively, for a rotation range of 90°. The rotation angle of the actuator is linearly related to time, which shows that its performance is controlled well. The novel screw-coupled piezoelectric actuator for driving an aperture features high resolution, high speed, simple structure and compact size.

Design and driving characteristics of a novel ‘pusher’ type piezoelectric actuator

This study proposes a novel ‘pusher’ type piezoelectric actuator based on clamping blocks, where a solid mover can be driven at a high resolution and with a designed stroke of 4 mm. The working principle of the actuator is presented and the design process of its key component ‘stator’ is described. Via finite element simulation, the rationality of the structure of the device was analyzed. The prototype actuator was manufactured and its main performance was tested. The driving characteristics of the proposed actuator produced the following experimental results. The movement resolution was 31.5 nm, the maximum speed was 248 μm s−1 and the maximum loading capacity was 123.5 N, verifying that it could meet the needs of precise positioning with a high resolution and a large load capacity. The actuator was also found to achieve various step speeds when the driving voltage and working frequency were changed.

Design and Fabrication of an Array Microejector Driven by a Shear-Mode Piezoelectric Actuator

This paper reports a novel actuating design that uses� the shear deformation of a piezoelectric actuator to deflect a� bulge-diaphragm for driving an array microdroplet ejector. In essence,� we employed a circular-shaped actuator poled radial direction with� remnant polarization normal to the actuating electric field for inducing� the piezoelectric shear effect. The array microdroplet ejector consists� of a shear type piezoelectric actuator, a vibration plate, two chamber� plates, two channel plates and a nozzle plate. The vibration, chamber� and nozzle plate components are fabricated using nickel� electroforming technology, whereas the channel plate is fabricated by� etching of stainless steel. The diaphragm displacement was measured� by the laser two-dimensional scanning vibrometer. The ejected� droplets of the microejector were also observed via an optic� visualization system.

Design and Performance Testing of a New Type Piezoelectric Rotary Actuator

Design and Performance Testing of a New Type Piezoelectric Rotary Actuator

Optimization of fixation elements parameters for ring type piezoelectric actuator generating elliptical movement

A novel design of ring type piezoelectric actuator with waves reflecting active elements (the fixation ele-ments) generating elliptical movement is proposed and analyzed in the paper. Numerical analysis by FEM with the aim to determine natural frequencies and modal shapes of the resonator was carried out and motion path of interaction contact point found. The best results of model analysis of cross ply and rota4tive movement were found. Results of numerical studies are discussed. DOI: http://dx.doi.org/10.5755/j01.mech.20.3.7388

Resonance frequency ratio control with an additional inductor for a miniaturized resonant-type SIDM actuator

A smooth impact drive mechanism (SIDM) is one type of piezoelectric actuator that converts a saw-shaped piezoelectric displacement to linear (or rotational) motion. For sufficient displacement, a soft-type multilayered piezoelectric element is essential; however, such a piezoelectric element prevents efficient driving due to its low quality factor. To overcome this problem, we proposed a resonant-type SIDM using a hard-type single-layered piezoelectric element. In this resonant-type SIDM, the first and third longitudinal resonant sinusoidal vibration modes were combined to obtain a quasi-saw-shaped waveform. To realize such a saw-shaped waveform, precise adjustment of the resonance frequency ratio is essential. However, it is not easy to regulate the resonance frequency ratio by just the transducer design because of the fabrication error. As a solution for this issue, this study proposes to adjust the frequency ratio by inserting an electrical inductor in series with the piezoelectric transducer. With this method, the resonance frequency ratio was controlled, and the rotor velocity increased as expected.

The ring type piezoelectric actuator generating elliptical movement

A design of ring type piezoelectric actuator generatig elliptical movement is proposed and analyzed in the paper. Elliptical movement is generated at the area of the actuator applying harmonic excitation signals with different phases. Numerical modeling based on finite element method was performed in order to find resonant frequencies and modal shapes of the actuator and to calculate the size of inner and outer radius, ensuring maximum rotation and bending movements under excitation scheme. Results of numerical studies are discussed. DOI: http://dx.doi.org/10.5755/j01.mech.19.6.6017

A new loudspeaker for low frequency radiation by linear motion type piezoelectric ultrasonic actuators

The authors had proposed new direct-radiator loudspeaker constructions with a conventional paper cone radiator driven by ultrasonic motors (USM), as a substitution for voice-coil motor. However, those models needed a revolution to linear motion conversion mechanism, and avoiding zero region non-linearity, like class A amplifier. These complications came from the conventional USM, since it is a rotational and having zero region non-linearity inherently. Here, the authors would propose a new mechanism by using new ultrasonic linear actuators, called longitudinal-bending multilayered transducers with independent electrodes (LBMTIE). The beauty of LBMTIE is linear and to control vertical motion and horizontal motion independently, hence zero region non-linearity avoided. Therefore, it is possible to substitute the voice-coil motor directly, which avoids the complicated mechanisms mentioned above. In this LBMTIE driven loudspeaker, vertical movement voltage be fixed and horizontal voltage is driven by audio signal, like voice-coil motor. In addition, there is a big contrast against conventional voice-coil motor, which is a typical transducer, as its electrical input and sound pressure output are direct proportion each other. This is because LBMTIE driven loudspeaker may behave a sort of modulator, which is not direct proportion in between input electric power and output sound pressure level.

Investigation of Oscillations of the Piezoelectric Actuator with Two-Directional Polarization

The recent trends in robotics and mechatronics necessitate for developing small-size multi-DOF motion systems. Piezoelectric actuators are one of the feasible solutions of this problem. An investigation of the contact point multicomponent oscillations of the beam type piezoelectric actuator with two-directional polarizations under different excitation regimes is presented in the paper. Polarization of the actuator has perpendicular directions on the first and second half of the actuator. Two-directional polarization of the actuator is used to achieve flexural oscillations of the actuator in two perpendicular planes. Superposition of longitudinal and flexural modes allows achieving oscillations of contact point in different planes. Electrodes of the actuator are divided into sections, and several excitation schemes are used to control a trajectory of the contact point movement. Numerical simulation and experimental study of piezoelectric actuator oscillations were performed. Elliptical motions of the contact point were obtained in different planes. Dependencies of contact point oscillation trajectories from excitation voltage phase and amplitude are determined at different excitation regimes.

벤더형 고응답 압전밸브의 주파수 특성에 관한 연구

Two kinds of piezoelectric actuator are applied to the valve for controlling the direction, the flow and the pressure of the fluid. One is a stack type piezoelectric actuator which has very fast response characteristics but very tiny displacement. The other is a bender type piezoelectric actuator which has also fast response characteristics but lower than the stack type one, and has longer displacement than the stack type one. So, the bender type piezoelectric actuator has advantage to apply to the valve for controlling a large amount of flow and fast on-off operating. In this study, the bender type piezoelectric pneumatic valve for color sorter is designed and fabricated. The new type high speed piezo valve with the both side supporting mechanism for high operating frequency and high reliability is discussed for separating the foreign body from the grains. Finally, the performance characteristics of a fabricated valve are analyzed and the frequency characteristics are also discussed for substituting the conventional type solenoid actuator.

CYLINDRICAL PIEZOELECTRIC MOBILE ACTUATOR BASED ON TRAVELLING WAVE

A design of cylindrical type piezoelectric mobile actuator is proposed and analyzed in the paper. Traveling wave is generated on the top area of the actuator applying harmonic oscillations with different phases. Electrodes of piezoceramic elements are excited by harmonic voltage with phase difference of 2π / 3. Numerical modeling based on finite element method was performed to find resonant frequencies and modal shapes of the actuator and to calculate the trajectories of the upper points movements under excitation scheme. Path-Planning algorithm presented for cylindrical piezoelectric mobile actuator.DOI: http://dx.doi.org/10.5755/j01.mech.18.5.2698

A miniaturized resonant-type smooth impact drive mechanism actuator

A smooth impact drive mechanism (SIDM) is one type of piezoelectric actuator that has been put into practical use. In previous SIDMs, soft-type multilayered piezoelectric elements with low mechanical quality factors were utilized, which meant it was difficult to generate high output power, and the multilayered structure was an obstacle to further miniaturization. We have proposed a resonant-type SIDM actuator, which has a simple structure, and uses combined resonant vibrations to achieve high output power. In the present study, a simple plate transducer was designed to realize the resonant-type SIDM principle. This compact actuator was composed of a hard-type single-layer piezoelectric element. The stator transducer was 10mm long and 2mm wide. Instead of a linear slider, a small bearing (6mm in diameter) was used as a moving part and was successfully driven based on the resonant-type SIDM principle. The voltage frequency was 288.0kHz for the first mode and 576.0kHz for the third mode, which was twice that of the first mode. By adjusting the preload and the phase difference between each voltage, the bearing was rotated at 400rpm. In addition, the driving direction could be reversed by modifying the phase difference.

Analysis of surface generation in ultra-precision machining with a fast tool servo

The fast tool servo (FTS) is one of the emerging ultra-precision machining technologies for the fabrication of high-quality optical microstructural surfaces. The diamond tool is fixed on the FTS, which is activated back and forth by a stacked type piezoelectric actuator. Optical microstructures with sub-micrometre form accuracy and nanometric surface finish can be fabricated without the need for any subsequent post processing. However, current understanding of the cutting mechanics and the factors affecting the surface generation in FTS machining is still far from complete. Although there has been some research work conducted to fill the research gaps with respect to FTS machining, most of the previous studies have been focused on the design of FTS for better performance and modelling characteristic of FTS actuators. The study of the process factors affecting surface generation in FTS machining has received little attention. As a result, this paper aims to analyse the effects of process parameters on surface generation in FTS machining. The factors being studied include spindle speed, feed rate, and depth of cut. A series of cutting experiments was carried out under various cutting conditions and the surface quality of the workpiece in terms of the form error and form defects were studied. Based on the results of the investigation, some recommendations for optimizing surface quality in the FTS machining process are discussed.

Fabrication and characterization of THUNDER actuators—pre-stress-induced nonlinearityin the actuation response

This paper documents an experimental and theoretical investigation into characterizing themechanical configurations and performances of THUNDER actuators, a type ofpiezoelectric actuator known for their large actuation displacements, throughfabrication, measurements and finite element analysis. Five groups of such actuatorswith different dimensions were fabricated using identical fabrication parameters.The as-fabricated arched configurations, resulting from the thermo-mechanicalmismatch among the constituent layers, and their actuation performances werecharacterized using an experimental set-up based on a laser displacement sensor andthrough numerical simulations with ANSYS, a widely used commercial softwareprogram for finite element analysis. This investigation shows that the presenceof large residual stresses within the piezoelectric ceramic layer, built up duringthe fabrication process, leads to significant nonlinear electromechanical couplingin the actuator response to the driving electric voltage, and it is this nonlinearcoupling that is responsible for the large actuation displacements. Furthermore, theseverity of the residual stresses, and thus the nonlinearity, increases with increasingsubstrate/piezoelectric thickness ratio and, to a lesser extent, with decreasing in-plane dimensions of thepiezoelectric layer.

Development of piezoelectric actuators for active X-ray optics

Piezoelectric actuators are widely utilised in adaptive optics to enable mirrors having an actively controlled reflective surface for the purpose of the wavefront correction by reducing the effects of rapidly changing optical distortion. Two new prototype adaptive X-ray optical systems are under development with the aim of approaching the fundamental diffraction limit. One proposed technology is microstructured optical arrays (MOAs) involving two or four piezoelectric strips bonded to a silicon wafer to produce a micro-focused X-ray source for biological applications, and which uses grazing incidence reflection through consecutive aligned arrays of channels obtained using deep silicon etching. Another technology is large scale optics which uses a thin shell mirror bonded with 20–40 piezoelectric actuators for the next generation of X-ray telescopes with an aim to achieve a resolution greater than that currently available by Chandra (0.5"). PZT-based piezoelectric actuators are being developed in this programme according to the design and implementation of the proposed mirror and array structures. Viscous plastic processing is chosen for the preparation of the materials system, which is subsequently formed and shaped into the suitable configurations. Precise controls on the thickness, surface finish and the curvature are the key factors to delivering satisfactory actuators. Unimorph type piezoelectric actuators have been proposed for the applications and results are presented regarding the fabrication and characterisation of such piezo-actuators, as well as the related design concepts and comparison to modelling work.

Lifetime Improvement for Full-Width-Array Piezo Ink Jet Print Head Using Matrix Nozzle Arrangement

Upon driving the unimorph type piezoelectric actuator of an ink jet in a high temperature high humidity environment (38°C/80%), many failures occurred after approximately 1 billion pulses. We hypothesized that the failures occurred due to hydrogen that was generated from the electrolysis of water, causing the piezoelectric element to deteriorate. Based on this hypothesis, we examined electrode materials to reduce the frequency of failures. We found that failure rate can be improved if material with high standard electrode potential is used as the electrode material on the high potential side and material with low standard electrode potential is used on the low potential side, and more specifically, if metal oxide is used for the electrode on the low potential side. Based on these findings, a combination of silver palladium for the electrode on the high potential side and stannous oxide (Sn x O y ) for the low potential side was used as the combination of electrode materials that can be formed at low cost. Upon implementing a running test with this combination of electrode materials under a high temperature high humidity environment, we confirmed that failures do not occur even at a continuous drive of 30 billion pulses and that the long-term reliability of the unimorph type piezoelectric actuator improved significantly.

Shock Resistance of a Disk-Drive Assembly Using Piezoelectric Actuators With Passive Damping

Current dual-stage actuator design uses piezoelectric patches only, without passive damping. In this paper, we propose a dual-stage servo system using enhanced active-passive hybrid piezoelectric actuators. Because they incorporate passive damping, the proposed actuators will improve the existing dual-stage actuators, giving them higher precision and better shock resistance. We report finite-element analyses of different types of piezoelectric actuators in a disk arm assembly under external shock and vibration. We modeled the viscoelastic damping layers in the hybrid actuators with the Prony series, whose parameters we determined from the dynamic frequency data of a nomograph. In the analyses, a shock impulse (175 g, 1 ms half sine) and a vibration impulse (350 g and 1 ms full sine) are applied at one end of the base, while the other end of the base is fixed. We evaluated and compared the responses of the disk arm assembly with different configurations of the piezoelectric actuators. The simulation results show that the enhanced active-passive hybrid actuator design would reduce the residual in-plane vibration induced during the shock, resist liftoff motion, and reduce the impact damage when the head slaps.

Study on Vibratory Linear Micro-feeder

The vibratory linear micro-feeder has developed to feed a difficult handling object as a micro-parts, a soft or membranous materials. Its track and spring strips are united by bending as continuous member, only the shim plate with bimorph type piezoelectric actuator. Then, the construction has the most impotant conditions. The first, it is easy to carry out the production, because, sensitivity for dimensions is low, that is lightly affected to manufacturing errors. And the second, structure of the feeder can be simplified. By giving an eye to fundamental mode of flexural vibration, dynamic deflection of the track can be suppressed, and is sufficiently smaller than horizontal amplitude even if flexural rigidity is not high. Therefore, it is possible for a simple micro-feeder as the micro-mechanism to be realized without assembly of many parts. The dynamic deflection can be reduced by higher rigidity of the bended corner at both track ends in the case of a long track. On the other hand, lower rigidity of the corner is more suitable for a short track. In the first trial, the normal feeding of the 1608 tip capacitor has sucessed by the thin track consisted of the shim plate and aspect ratio 2, length ratio of the track to the actuating member. Feeding of a hydrophilic gel, the most difficult feeding object, was realized by the specially devised plane with water of the suitable quantity.

2306 進行波型圧電ポンプの研究 : 振動板の挙動(機械設計と機構,一般講演)

This study is about a novel small piezoelectric pump. The pump utilizes a thin vibration plate on which bimorph type piezoelectric actuators generate progressive wave. Characteristics of the pump are investigated by experiments. It is observed that direction of flow depends on driving frequency and the direction does not always agree with phase of driving voltage signals applied to the piezoelectric elements. Behaviors of several part of the vibration plate in the pump case filled or not filled with water are investigated with laser Doppler vibration sensor. It is clarified that phase of sinusoidal vibration of the each part does not agree with the phase of driving signal. Interaction between vibration plate and water may cause the phenomenon.

402 積層型ピエゾアクチュエータによる実大鉄道車両の弾性振動のアクティブ制御

In recent years, railway vehicles are becoming lighter since it corresponds to improvement in the running speed. However, this causes the deterioration of the body rigidity, and leads to the increase in a vertical bending vibration of the body. In addition, the deterioration of riding comfort concerns to this issue, because the natural frequency of the 1st bending vibration and inverse phase vibration overlaps with human's uncomfortable sensitive frequency band. The objective of this research is to reduce these bending vibrations of full-scale vehicle by stack type piezoelectric actuators and to investigate the influence of the local deformation by larger size actuator.