PZT Actuator Research Articles

Analysis and modeling of hysteresis of piezoelectric micro-actuator used in high precision dual-stage servo system

A dual-stage servo system consists of a primary coarse actuator for facilitating large motion and a secondary micro-actuator for small but precise motion to improve tracking performance. Piezoelectric micro-actuator made from lead zirconate titanate (PZT) has been a popular choice for the secondary stage. However, the advantage gained by the resolution of the secondary PZT actuator is reduced by its inherent hysteresis nonlinearity. Model based hysteresis compensation techniques are preferred due to their simplicity and fast response. Identification and modeling are two substantial parts in such model-based techniques. This paper presents a rigorous analysis and modeling of the hysteresis of PZT micro-actuator. Modified Generalized Prandtl-Ishlinskii and Coleman-Hodgdon models are studied. Identification of the model through nonlinear least square and particle swarm optimization are examined and compared. Several analyses are done through tuning of the model parameters and identification techniques. Experimental analysis and simulation results underscore the effectiveness of this modeling approach. Finally as a design example, a dual-stage simulation analysis is done to show the effectiveness of systematic modeling on hysteresis compensation.

Influence of the Thermoplastic Type on the Thermal Evolution of a Piezoceramic Patch During the Manufacture of a Smart Thermoplastic Part by Injection Molding Process

The frame of the paper is the integration of PZT actuators and sensors within thermoplastic mechanical structures. The objective of the work reported here was to select the appropriate thermoplastic materials for the smart thermoplastic manufacturing. In order to reach this objective, a comparative study was realized between different thermoplastic materials taking into consideration the PZT patch maximum temperature, the overheat time of the PZT patch during injection process, and the PZT loss in piezoelectric properties due to its thermal fragility.

Multi-layered piezoelectric energy harvesters based on PZT ceramic actuators

In this study, we have investigated 1–3 story structured piezoelectric energy harvesters based on lead zirconate titanate (PZT) multi-layered actuators. These piezoelectric energy harvesters were fabricated using Pb(Zr,Ti)O3 based ceramic actuators. The multi-layered PZT actuators were based on green sheets that were prepared by a tape casting process. The ceramic actuators were attached on metallic electrodes with poled states. The structures were filled with polydimethylsiloxane (PDMS). The multi-layered piezoelectric energy harvesters were stacked as single-story structured, double-story structured, and triple-story structured devices, respectively. Generated output voltages, stored power, and maximum output power with various loads of the piezoelectric energy harvesters with various story structures were analyzed.

Fabrication and Characterization of Microstacked PZT Actuator for MEMS Applications

A microstacked PZT actuator of dimensions 8 mm × 0.8 mm × 0.4 mm and capable of 2.3-μm actuation under a voltage of 100 V was fabricated and characterized. This actuator was then integrated into a silicon microstage with dimensions of 20 mm × 20 mm × 0.4 mm requiring actuation by a miniaturized actuator. The microstage was designed containing a Moonie amplification mechanism in order to further amplify the actuation of the stacked PZT actuator. Experimental characterization of the microstage performance indicated that the combination of a stacked PZT actuator with the Moonie amplification mechanism was successful in enabling high amplification of the microstage to ~15 times the original displacement of the PZT actuator. A displacement of 16.5 μm at an applied voltage of 60 V and a resonant frequency of 456 Hz in the lateral vibration mode was observed. The relationship between the actuator parameters and the microstage design and performance was also discussed in order to show that the customized fabrication of a miniature actuator was imperative for the successful design of a high area-efficiency microstage. Analytical derivation of the displacement of the stacked PZT actuator was also carried out in order to evaluate the effectiveness of the fabricated actuator compared with the ideal stacked PZT structure.

Continuous Flow Controlled Synthesis of Gold Nanoparticles Using Pulsed Mixing Microfluidic System

To prepare the gold nanoparticles (AuNPs) with uniform sizes, fine morphology, and good monodispersity, a pulsed mixing microfluidic system based on PZT actuation was presented. The system includes PZT micropump and Y type micromixer. By adjusting voltage (entrance flow rate), pulsed frequency, phase, and other parameters, a variety of mixing modes can be achieved, so as to realize the controllable synthesis of nanoparticles in a certain range. By numerical simulation and analysis, the channel section size, entrance angle, and pulse frequency were optimized. Based on the optimized structure and working parameters, the test prototype has been manufactured in lab, and the related synthesis tests of AuNPs were carried out. The test results indicate that AuNPs with uniform morphology and good monodispersity can be synthesized using the system with the section size (0.4 mm × 0.4 mm), the entrance channel angle (60°) under condition of the pulsed frequency (300 Hz), and the entrance flow rate (4 mL/min). The average diameter and its standard deviation of AuNPs synthesized were 21.6 nm, 4.83 nm, respectively. The research work above can be applied to the fields such as the controlled synthesis of noble metal nanoparticles, biomedicine, and microchemical system.

PID+CMAC Neural Network Control of Micro Positioning Platform

Because of some intrinsic properties of the PZT actuator, such as hysteresis, creep and nonlinearity effect, it’s difficult to achieve satisfactory results and control precision for conventional PID controller. In order to improve the control precision of the PZT driven of micro positioning platform, we proposed a CMAC neural network based on PID control scheme, which has the characteristics of realizing feed-forward control and obtaining the inverse dynamic model of controlled object by the CMAC neural network controller, and realizing feedback control by conventional controller, which can ensure the system stability and suppress disturbance. Form MATLAB simulation results, it demonstrates that the CMAC+PID control algorithm can be able to improve the control precision and response time of the system, and enhance the anti-interference ability and robustness, comparing with the traditional digit PID control algorithms.

Analysis and compensation of hysteresis of PZT micro-actuator used in high precision dual-stage servo system

Piezoelectric micro–actuator made from (PZT) has been a suitable choice as the secondary actuator of a dual–stage actuator system. However, like any other piezoelectric actuator, this secondary PZT micro–actuator also exhibits hysteresis which is the inherent nonlinearity characteristic of piezoelectric material. Therefore, the advantage gained by the precision of secondary actuator is somewhat lost by this hysteresis, if not compensated. This paper proposes a rigorous technique for analysing, identifying and compensating the hysteresis of PZT actuator used in dual–stage actuator system. Identification and compensation are the two parts of the paper. In the first part of the paper, the parameters of generalised Prandtl–Ishlinskii (GPI) model are identified offline by particle swarm optimisation (PSO) technique. In compensation part, inverse GPI as the hysteresis compensator is obtained from the identified hysteresis model. Then in case of parameter uncertainty, PSO–based online tuning method is employed to adaptively adjust the parameters of inverse GPI model. For the linear controller of dual–stage, a simple design approach is followed. Simulation results show that the proposed technique can be efficiently used for the identification and compensation of hysteresis of PZT micro–actuator.

Structural health monitoring technology for a full-scale aircraft structure under changing temperature

AbstractThis paper presents optimal operating modes for the factors to maximise the detection capability of a given SHM technology in service environment. Firstly, an orthogonal experiment was performed to determine the importance ranking of the influence factors. Through the test, it is found that operating temperatures for SHM hardware and excitation frequencies for PZT actuator were the most critical factors. Then, numerical model of Lamb waves generated and received by PZT sensors were presented to predict the distribution of response signal amplitudes under changing temperature. Verification tests were carried out on a glass fibre reinforced composite plate at different temperatures. The comparison between the analytical prediction and test results was presented and temperature-dependent optimal frequencies for PZT actuators were obtained. Finally, SHM experiments of full-scale horizontal composite structures are presented. The detection capability of the SHM technology applications of aircrafts in real world is verified by the experimental results.

Scalable, MEMS-enabled, vibrational tactile actuators for high resolution tactile displays

The design, fabrication, and characterization of a new type of tactile display for people with blindness or low vision is reported. Each tactile element comprises a piezoelectric extensional actuator that vibrates in plane, with a microfabricated scissor mechanism to convert the in-plane actuations into robust, higher-amplitude, out-of-plane (vertical) vibrations that are sensed with the finger pads. When the tactile elements are formed into a 2D array, information can be conveyed to the user by varying the pattern of vibrations in space and time. Analytical models and finite element analysis were used to design individual tactile elements, which were implemented with PZT actuators and both SU-8 and 3D-printed scissor amplifiers. The measured displacements of these 3 mm × 10 mm, MEMS-enabled tactile elements exceed 10 µm, in agreement with models, with measured forces exceeding 45 mN. The performance of the MEMS-enabled tactile elements is compared with the performance of larger, fully-macroscale tactile elements to demonstrate the scale dependence of the devices. The creation of a 28-element prototype is also reported, and the qualitative user experience with the individual tactile elements and displays is described.

Bio-inspired bending actuator for controlling conical nose shape using piezoelectric patches.

In this paper, a bio-inspired bending actuator was designed and fabricated using piezoelectric patches and cantilever-shaped beam for controlling nose shape. The aim of this study is to investigate the use of the bending actuator. PZT and single crystal PMN-PT actuators were used to generate translational strain and shear stress. The piezoelectric patches were attached on the clamped cantilever beam to convert their translational strains to bending motion of the beam. First, finite element analysis was performed to identify and to make an accurate estimate of the feasibility on the bending actuation by applying various voltages and frequencies. Based on the results of the FEM analysis, the experiments were also performed. Static voltages and dynamic voltages with various frequencies were applied to the bending actuators with PZTs and PMN-PTs, and the rotation angles of the nose connected to the top of bending actuators were measured, respectively. As the results, the bending actuator using PMN-PT patches showed better performances in all cases. With the increases of signal frequency and input voltage, the rotation angle also found to be increased. Especially at the frequency of 5 Hz and input voltage of 600 V, the nose generated the maximum rotation angle of 3.15 degree.

On-board SHM System Architecture and Operational Concept for Small Commuter Aircra

Significant R&D progress has been done in the area of SHM technologies in recent years. However real SHM application on aircraft board is still challenging and puts specific requirements on the SHM system design and operation. These challenges include assurance of reliable and provable damage detection capabilities, taking over decision-making responsibilities instead of a human inspector and other challenges related to on-board installation and operation during the flight. Further, minimal weight and dimension, and system reliability and durability should be considered. Due to these challenging requirements the SHM has not been widely implemented in aerospace industry yet.The paper deals with system architecture and operational concept of SHM system for L-410 NG commuter aircraft. The SHM system is based on excitation, sensing and analysis of ultrasonic guided waves using PZT actuators / sensors. The SHM system is designed for monitoring of PSEs of metallic airframe that are hard to access or completely inaccessible for common inspection methods used in the aircraft maintenance. The design puts emphasis on integration of the SHM system within aircraft avionic system in order to achieve highly automated data acquisition and data transfer process to make the health data available for on-ground analysis. Finally, scenario of the SHM system operation in accordance to the L-410 NG maintenance plan is proposed in the paper. The scenario assumes replacement of common inspections that are done within regular maintenance checks by the automated inspections using SHM system. Challenges of the proposed scenario from the point of view of the aircraft certification and operation are discussed as well.

Errors in shearography measurements due to the creep of the PZT shearing actuator

Shearography is a modern optical interferometric measurement technique. It uses the interferometric properties of coherent laser light to measure deformation gradients on the µm m − 1 level. In the most common shearography setups, the ones employing a Michelson interferometer, the deformation gradients in both the x- and y-directions can be identified by setting angles on the shearing mirror. One of the mechanisms for setting the desired shearing angles in the Michelson interferometer is using the PZT actuators. This paper will reveal that the time-dependent creep behaviour of the PZT actuators is a major source of measurement errors. Measurements at long time spans suffer severely from this creep behaviour. Even for short time spans, which are typical for shearographic experiments, the creep behaviour of the PZT shear actuator induces considerable deviation in the measured response. In this paper the mechanism and the effect of PZT creep is explored and demonstrated with measurements. For long time-span measurements in shearography, noise is a limiting factor. Thus, the time-dependent evolution of noise is considered in this paper, with particular interest in the influence of external vibrations. Measurements with and without external vibration isolation are conducted and the difference between the two setups is analyzed. At the end of the paper some recommendations are given for minimizing and correcting the here-studied time-dependent effects.

Feasibility of using PZT actuators to study the dynamic behavior of a rotating disk due to rotor-stator interaction.

In this paper, PZT actuators are used to study the dynamic behavior of a rotating disk structure due to rotor-stator interaction excitation. The disk is studied with two different surrounding fluids—air and water. The study has been performed analytically and validated experimentally. For the theoretical analysis, the natural frequencies and the associated mode shapes of the rotating disk in air and water are obtained with the Kirchhoff-Love thin plate theory coupled with the interaction with the surrounding fluid. A model for the Rotor Stator Interaction that occurs in many rotating disk-like parts of turbomachinery such as compressors, hydraulic runners or alternators is presented. The dynamic behavior of the rotating disk due to this excitation is deduced. For the experimental analysis a test rig has been developed. It consists of a stainless steel disk (r = 198 mm and h = 8 mm) connected to a variable speed motor. Excitation and response are measured from the rotating system. For the rotating excitation four piezoelectric patches have been used. Calibrating the piezoelectric patches in amplitude and phase, different rotating excitation patterns are applied on the rotating disk in air and in water. Results show the feasibility of using PZT to control the response of the disk due to a rotor-stator interaction.

Studies on the Active Control and Placement of Piezoelectric in Piezoelectric Cantilever Beam

The active vibration control of the flexible cantilever beam with PZT actuators was studied in this paper, and the principle and the method of the active vibration control were analyzed. First, using the balanced reduction method to reduce the model was carried out; the reduced model would be controlled. The placement of the piezoelectric actuators was utmost important, the optimization arrangement of the piezoelectric actuators was studied in this paper basing on the modal influential matrix of the piezoelectric actuators in order to make it to maximize its effectiveness to realize active control. Next step the LQG/LTR method is used to control the structure, then the LQR method was adopted to control the beam, and the two methods were compared. The results show that the LQG/LTR method to control the beam will realize effective control if only the treatment is adequate, when the acoustic noise and Interference were added to the system.

Novel piezoelectric actuator control slider using transverse-mode deformation

This work proposes a novel structure design of active slider with a piezoelectric actuator at the top of the slider body and a soft layer between the substrate and head elements, to efficiently control the flying height of slider. A parametric simulation was performed to obtain an optimize dimension of PZT actuator and the most efficient soft material. Then three types of slider structures were designed and investigated with considering air bearing effects to achieve large actuation efficiency.

Design and analysis of an X–Y parallel nanopositioner supporting large-stroke servomechanism

In this paper, we consider the design and analysis of an X–Y parallel piezoelectric-actuator-driven nanopositioner with a novel two-stage amplifying mechanism, where the mechanical design is optimized to achieve a large stroke and high-natural frequency for the purpose of high-performance servomechanism. The parallel kinematic X–Y flexure mechanism provides good geometric decoupling. The kinematic and dynamic analysis shows that the proposed design has a large work space and high bandwidth, which is further verified by finite-element analysis. The analysis results demonstrate that the designed nanopositioner has a large workspace more than 200 µm and a high-natural frequency at about 760 Hz. Furthermore, the dynamical model of the nanopositioner, including the dynamics of the PZT actuators, is also generated from the perspective of input/output transfer functions, and the parameters are identified by frequency-response experiments, which can be used for nano precision servomechanism.

Effective Models of PZT Actuators for Numerical Simulation of Elastic Wave Propagation

In this study, to accurately identify the functions of piezoelectric actuators and sensors for the generation and collection of elastic waves in typical engineering structures, several effective models of surface-bounded flat PZT disks are further developed and validated for numerical modelling of elastic wave propagations. Based on these models, a series of finite element models of elastic waves in plates are devised using both implicit and explicit dynamics analysis techniques and those numerical simulations are conducted and verified one another. The results flowed from the present research is being used to study the elastic wave propagation in pipes and develop an online structural health monitoring (SHM) system with an integrated piezoelectric actuator-sensor network.

적층 벤더형 압전식 공압밸브의 내구 특성

In this paper, pneumatic valve which consists of valve body, valve controller, nozzle and a multi-bender PZT actuator was suggested and fabricated. The fabricated pneumatic valve was experimented for performance evaluation. From the experimental results, we know that the flow rate of the suggested valve is 23 lpm at the pressure difference of 1bar and the maximum flow rate is 30 lpm at the pressure difference of 4 bar. The flow rates after endurance test of 9.8 million were 22.57 lpm and 28.62 lpm at the pressure difference of 1bar and 4bar, respectably. Finally, it was verified that the B10 life of the suggested pneumatic valve is over 50 million.

Quantitative damage image construction in plate structures using a circular PZT array and lamb waves

A circular PZT ceramic wafer array based on a process of receiver beamforming is developed for damage identification in plate structures, and a method of quantitative damage image construction is presented using Lamb wave signals received from the array. Design parameters of the circular PZT array, including diameter of the PZT array, number of PZT wafers and steering angle, are investigated. Characteristics related to magnitude of the array response, viz. the reflection coefficient and distance between the damage and the array, are also analyzed. It is demonstrated that, because of the unique configuration of the PZT array, the magnitude of the array response is independent of the direction of the damage location relevant to the array. Exact propagation path of wave propagation is adopted, and therefore the damage can be reconstructed even in the near field surrounding the PZT array. To validate the proposed method, a circular PZT array consisting of one PZT actuator and several PZT sensors is used in experiments to identify damage in an aluminum plate. By considering the attenuation of Lamb wave propagation in plate structures, quantitative image construction is implemented for damage of different severities and distances from the array.

Analysis of a three-dimensional FEM model of a thin piezoelectric actuator embedded in an infinite host structure

In this paper, we adopted a two-dimensional analytical electro-elastic model to predict the stress distributions of the piezoelectric actuator in 3D case. The actuator was embedded in an elastic host structure under electrical loadings. The problem is reduced to the solution of singular integral equations of the first kind. The interfacial stresses and the axial normal stress in both plane stress state and plane strain state were obtained to study the actuation effects being transferred from the actuator to the host. The stress distributions of the PZT actuator in different length and different thickness were analyzed to guarantee the generality. The validity of the present model has been demonstrated by application of specific examples and comparisons with the corresponding results obtained from the Finite Element Method.