Single Piezoelectric Actuator Research Articles

A purely centered and non-redundant piezoelectric stick-slip rotary stage with force amplification

This paper proposes a purely center-rotation and non-redundant piezoelectric stick–slip rotary stage with force magnification. A bridge driving mechanism with centrosymmetric actuation feet is proposed, and its tilt angle can be adjusted to regulate the clamping force amplification characteristics, thus improving load capacities. Meanwhile, only a single piezoelectric actuator is used, and the driving mechanism is built in the circular slider, hence achieving non-redundant, purely centered rotation and improving the structural compactness. Theoretical calculations and simulation analyses of single-step rotation angles and force amplification of the rotary stage are carried out. In addition, a system dynamics model with electromechanical, rigid-flexible, and friction coupling properties is established. Finally, a prototype is fabricated, and various experiments are conducted. The designed bridge driving mechanism amplifies the piezoelectric actuation force by 2.8 times, and the stick–slip rotary stage has a maximum load of up to 9 kg. Also, the stage can rotate more than 360°, and the angular resolution is 0.1265 μrad, demonstrating superior performances of the non-redundant center-rotation stage.

Coupled hysteresis and resonance control of three-degree-of-freedom tip-tilt-piston piezoelectric stage

In order to solve the coupled hysteresis and resonance problems in three-degree-of-freedom tip-tilt-piston piezoelectric stage, a coupled hysteresis model and a coupled integral resonance compensation model are designed. The inverse coupled hysteresis feedforward control combined multi-axis coupled resonance control and high-gain integral tracking controller are used to improve the tracking speed and positioning accuracy of the stage. Firstly, a kinematic model of the stage is built to translate the three-degree-of-freedom motion of the end-effector into the outputs of three piezoelectric actuators. Then, a coupled hysteresis model based on the rate-dependent Prandtl–Ishlinskii model is established and parameterized to simultaneously compensate for the hysteresis of a single piezoelectric actuator and the coupled hysteresis between multiple piezoelectric actuators. The effectiveness of the model is verified by open-loop and closed-loop inverse model feedforward control experiments. Afterwards, a coupled integral resonance compensation model is also established and parameterized to suppresses the resonance and expand the system bandwidth. Finally, the proposed controller is used to conduct tracking experiments on a composite signal, and the results show that the accuracy and speed of trajectory tracking are further improved, and the mechanical coupling between axes are significantly reduced.

Design, analysis, and experimental investigations of an asymmetrical under-actuated micro-gripper

In this paper, we present a new asymmetrical under-actuated micro-gripper which can perform twisting and gripping operation to the target simultaneously actuated by a single piezoelectric actuator. Two improved hybrid amplification mechanisms were designed integrated with three different flexure hinges to enhance dynamic performances. Kinematics and dynamics models of the micro-gripper including input stiffness, displacement amplification ratio, and natural frequency based on pseudo-rigid-body method and Lagrange’s equations were derived. Proposed models were evaluated by finite element simulation studies. Experimental results shown that our designed micro-gripper possesses good performance in terms of clamping reliability and dynamic response.

An Inchworm and Stick-Slip Dual Mode Piezoelectric Linear Actuator for Cell Injection

Cell injection system for biomedical engineering demands that actuators have large stroke, high resolution and speed for cell positioning and injection. Single mode piezoelectric actuators could meet some of these requirements but hardly all. Stick-slip actuator is easy to achieve high-speed operation, but it is prone to setback; The speed characteristics of the inchworm actuator are lower than those of the stick-slip actuator, but the step is more stable and the setback is lower. This study proposes an inchworm and stick-slip dual mode piezoelectric actuator (ISSPA) for cell injection. It integrates two working modes into one actuator and both modes drive the same slider. The stick-slip mode works at high frequency for fast positioning to the cell and the inchworm mode drives the needle to puncture the cell membrane and accurately locates to the specified location. The structure and working principle of the ISSPA are provided. A prototype of the proposed ISSPA is fabricated and experiments are conducted. When the driving voltage of the piezoelectric stack is 100 V and the frequency is 500 Hz,the maximum speed of the ISSPA is 2.287 mm/s in the stick-slip mode. When the driving voltage of the piezoelectric stack is 60 V, the frequency is 3 Hz and the load is 0.5 kg,the minimum step displacement is 57 nm in inchworm mode. Demonstration of cell injection is carried out by using the ISSPA to positioning and puncturing a zebrafish embryo. Fast positioning with the stick-slip mode and accurate puncture with the inchworm mode are achieved with the ISSPA alone, taking 12 seconds for the whole injection process. It could be expected to apply the ISSPA to cells with wide range of diameter, as the frequency of the stick-slick mode and the voltage of the inchworm mode could be well regulated.

A non-redundant piezoelectric center-rotation platform with a single-layer structure and a large working range

This paper reports the design, modeling, and testing of a new single-layer center-rotation platform driven by a single piezoelectric actuator. The platform avoids actuator redundancy and exhibits a large rotation angle, high-precision resolution, and high resonant frequency. The pure center- rotation motion is realized by combining the improved Scott-Russell (SR) mechanism and lever- guided structure. The auxiliary stiffness mechanism at the input end of the SR mechanism also improves the stability of the rotation platform. An analytical model is established based on the finite element method, and the key parameters affecting the structural performance are investigated. A prototype is finally manufactured, and several experiments are conducted to test the proposed platform. The experimental results show that the rotation angle is 16.8 mrad, the resonant frequency is 527.3 Hz, and the resolution is 0.29 μrad. Thus, the platform is capable of precision center rotation.

Development of a Novel Flexure-Based XY Platform Using Single Bending Hybrid Piezoelectric Actuator

In this article, a novel flexure-based XY platform using a bending hybrid piezoelectric actuator was proposed, which was inspired by a classical piezoelectric stack-actuated platform. First, the stack-actuated platform was designed, the configuration and working principle of the bending hybrid piezo-actuated platform were illustrated. Then, theoretical analyses were conducted to design the piezo-actuated platform, the finite element method was employed for the static and dynamic analyses, and the prototypes of the two platforms were fabricated. Eventually, a series of tests were carried out to verify the theoretical and simulated results, and to investigate and compare their output characteristics. The experimental results revealed that the proposed piezo-actuated platform could achieve a motion range of 16.48 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> m × 16.84 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> m and the coupling error of less than 0.59%. Furthermore, the hysteresis ratios were about 8.3% and 8.2%, the first-order bending frequencies were 2162 and 2303 Hz in two axes, the displacement resolution was about 4.31 nm, and the steady-state displacement deviations of the point-to-point positioning control both are within ±30 nm in two axes. Compared with the traditional stack-actuated platform, the piezo-actuated platform not only had positive and negative output displacement, but also possessed superior performance, including low cross-coupling, low hysteresis, and high resolution, which was expected to be used in nanopositioning and micro/nanomanipulation.

Design and experimental evaluation of an inchworm motor driven by bender-type piezoelectric actuators

Piezoelectric actuators (PEAs) are widely used in ultra-precision detection platforms where nano-precision and non-magnetic features are required. With the development of the semiconductor industry, actuators develop toward the tendency of smaller size, higher precision, and longer travel. However, these demands are difficult to meet merely by virtue of a single piezoelectric actuator or a simple structured inchworm piezo motor, which makes it necessary to develop a new drive mode following a different drive principle. In this paper, a novel inchworm piezo motor with bender-type PEAs in phalanx distribution was proposed, which facilitates in reducing the dimension of the motor and enhances the performance and stability of the piezo motor. For the purpose of accommodating the bender-type PEAs and providing the preloads to the bender-type PEAs, a flexible mechanism housing was designed and the modal analysis was finished, avoid resonance and reduce structural vibration. Experimental results show that the resolution of the developed motor is 2 nm or less under the laser interference with an adoption rate of 10 MHz and a resolution of 0.1 nm, while the maximum stroke is over 19 mm at the constant speed of 2.3 mm s−1, and the maximum output force is 41.6 N.

Liquid cooling of stacked piezoelectric actuators for high-power operation

In this article, we propose a liquid cooling solution to reduce the temperature rise and expand the working range of stacked piezoelectric actuators (PEAs) for high-frequency and large-stroke operation. Based on an analysis and preliminary testing of the power dissipation and temperature rise, a specific liquid cooling solution for a single PEA is designed and its effectiveness is verified through experiments. To incorporate liquid cooling into a high-bandwidth fast steering mirror (FSM) system driven by PEAs, a compact and self-contained cooling unit is proposed and evaluated. Subsequent experimental results validate its effectiveness, but also show some deficiencies for this cooling solution. To further improve the cooling efficiency, two new coolants are adopted based on an analysis of the heat transfer coefficient, and a suitable direct liquid cooling solution is established. Experimental results show that the cooled PEA can operate continuously over 8 kHz with a peak-to-peak voltage of 100 V whilst its maximum temperature is restricted to around 40 °C using this cooling solution. The reliability and coolant insulation properties have been verified by a 3-month long continuously operational test.

Design and analysis of a two-degrees-of-freedom monolithic compliant piezoelectric microgripper

This paper presents the design, modeling, and testing of a compliant two-degrees-of-freedom microgripper using a single piezoelectric actuator. It can move along the x- and y-directions by combining double-leaf bridge and parallelogram mechanisms. An analytical model is established using the finite-element method. The displacement amplification ratio, natural frequency, and output coupling ratio are analyzed using ANSYS software. An experimental test system is built to verify the open-loop performances. Experimental results show that the displacement amplification ratios in the x- and y-directions are 30.8 and 8.6. The first resonant frequencies in the x- and y-directions are 123.3 and 546.9 Hz. If an input displacement of 10 μm is applied, the operating ranges in the x- and y-directions are 0–616.6 μm and 0–51.0 μm, and the gripping force range is 0–25.8 mN. Experimental results validate the feasibility of the theoretical model and simulation analysis. Also, closed-loop trajectory control is conducted to reduce the hysteresis nonlinearity and achieve a high control accuracy for the new microgripper.

“Generation III” Piezoelectric Single Crystals Developed by Solid-State Single Crystal Growth Method

Crystallographically engineered Relaxor-PT single crystals, specifically PMN-PT (Generation I) and PIN-PMN-PT/PMN-PZT (Generation II), offer much higher piezoelectric and electromechanical coupling coefficients (d33&gt;1,500 pC/N, k33&gt;0.9), when compared to polycrystalline PZT-5H ceramics (d33&gt;600 pC/N, k33&gt;0.75). Recently Ceracomp Co., Ltd. (www.ceracomp.com) has developed the solid-state single crystal growth (SSCG) technique and successfully fabricated Gen III PMN-PZT single crystals modified with acceptors or donors. The piezoelectric constants (d33) of (001) Gen III PMN-PZT single crystals were measured to be higher than 4,000 pC/N and thus about two times higher than those of PMN-PT/PZN-PT (Gen I) and PIN-PMN-PT/PMN-PZT (Gen II) single crystals. The Gen III PMN-PZT single crystals have been firstly applied to single crystal-epoxy composites, ultrasonic transducers, piezoelectric sensors, and piezoelectric actuators. In this paper we introduce the development of Gen III PMN-PZT single crystals, piezoelectric composites and multilayer single crystal actuators.

A Compact 2-DOF Micro/Nano Manipulator Using Single Miniature Piezoelectric Tube Actuator

Micro/nano manipulators using piezoelectric actuators are extensively applied in precision manipulation fields. In this article, a novel 2-DOF micro/nano manipulator with compact structure is proposed, designed, fabricated, and tested. Different movers can be actuated by only single miniature piezoelectric tube actuator (PTA) to achieve multimotion forms, including 2-DOF linear–linear motion, linear–rotary motion, and rotary–rotary motion in two orthogonal directions. Above all, the configuration and operating principle are amply depicted. Then, the theoretical analyses are accomplished to design the PTA, and the finite-element method is undertaken to validate the theoretical modeling. Ultimately, a prototype of the manipulator is manufactured and experimentally investigated for its output performances. The test results indicate that the developed manipulator can achieve the maximum rotary speed of 0.171 rad/s around the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> -axis and 0.169 rad/s around the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Y</i> -axis. Furthermore, the angular displacement resolutions are measured to be 0.54 and 0.57 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> rad around <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> - and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Y</i> -axis, respectively. All the results state that the developed micro/nano manipulator not only has distinct multimotion outputs, but also possess superior characteristics in terms of both motion range and displacement resolution, which is expected to be applied into precise positioning and microassembly.

Active control of multiscale features in wall-bounded turbulence

This study experimentally investigates the impact of a single piezoelectric (PZT) actuator on a turbulent boundary layer from a statistical viewpoint. The working conditions of the actuator include a range of frequencies and amplitudes. The streamwise velocity signals in the turbulent boundary layer flow are measured downstream of the actuator using a hot-wire anemometer. The mean velocity profiles and other basic parameters are reported. Spectra results obtained by discrete wavelet decomposition indicate that the PZT vibration primarily influences the near-wall region. The turbulent intensities at different scales suggest that the actuator redistributes the near-wall turbulent energy. The skewness and flatness distributions show that the actuator effectively alters the sweep events and reduces intermittency at smaller scales. Moreover, under the impact of the PZT actuator, the symmetry of vibration scales’ velocity signals is promoted and the structural composition appears in an orderly manner. Probability distribution function results indicate that perturbation causes the fluctuations in vibration scales and smaller scales with high intensity and low intermittency. Based on the flatness factor, the bursting process is also detected. The vibrations reduce the relative intensities of the burst events, indicating that the streamwise vortices in the buffer layer experience direct interference due to the PZT control.

A compact linear-rotary impact motor based on a single piezoelectric tube stator with two independent electrodes

A compact linear-rotary impact motor based on a single piezoelectric tube actuator is proposed. The motor can realize independent linear and rotary motions. With two independent electrodes, the piezoelectric actuator has an outer diameter of 6 mm, a thickness of 0.5 mm, and a length of 25 mm. The actuator produces a maximum axial displacement of 2.17 µm with a driving voltage of 720 Vp-p (peak-to-peak driving voltage), and it produces a maximum torsional angle of 599.98 µrad with a driving voltage of 720 Vp-p. The prototype motor can achieve the independent linear velocities of 6263.45 µm/s and -6331.58 µm/s in the positive and negative directions of motions under the saw-shaped driving voltage of 560 Vp-p at 8 kHz. The motor can realize the independent rotary velocities of 1.22 × 106µrad/s and -1.21 × 106µrad/s in the two motions under the saw-shaped driving voltage of 560 Vp-p at 9 kHz. The maximum output force of the motor is 0.45 N, and the maximum output torque is 0.80 mN m for linear and rotary motions, respectively.

Linear Piezoelectric Motor for Topography Detector of Diamond Wire

In topography detection procedures for diamond wire, precision motion control is one of the key preconditions; the motion control unit of detection needs both micron resolutions and centimeter strokes. In this paper, a linear motor with four sets of multilayer piezoelectric actuators was developed to achieve an actuator with high resolution and a large stroke. The stroke depended on the guideways of the system, which mar enlarged the stroke of a single multilayer piezoelectric actuator. The mechanism of differential actuation was analyzed by dividing an operation cycle into several states. A symmetrically arranged four-foot design was proposed, and a corresponding excitation method was devised. A prototype was fabricated to conduct a proof-of-concept operation test. Experimental results validated the feasibility of the prototype with a 10 mm stroke. The speed of the prototype increased when the amplitudes of driving voltage signals increased from 30 V to 100 V. Within the frequency range of 1 Hz to 120 Hz, the speed increased initially then decreased with driving frequency, the maximum of which was at 100 Hz. With an excitation voltage signal of 100 V and 100 Hz, the speed reached a maximum of 740 μm/s. With an excitation voltage signal of 30 V and 120 Hz, the resolution of the prototype reached 0.26 μm. The prototype satisfies precision motion control of topography detection for diamond wire. This work also provides an option for automatic systems that require high resolutions and large strokes.

Inertial motor on a single piezoelectric actuator for a low-temperature near-field scanning optical microscope.

The impact of such factors as the shape of the applied voltage pulse, the friction force, and the mass of the movable part on the motor operation at low temperatures is experimentally investigated. Important added features in the motor design are support springs. These springs prevent one part of the slider clamp from shifting relative to the other during motion. The optimization of the factors listed above provided for reliable withdrawal of the microscope's fiber probe with a speed of up to 0.2 µm/step at a temperature of 5 K.

Multimodal suppression of vibration in smart flexible beam using piezoelectric electrode-based switching control

This paper describes an active vibration control system combining a piezoelectric electrode configured with a novel switching control system to achieve multimodal vibration suppression in smart flexible structures embedded with only a single piezoelectric actuator. The fact that high-frequency vibrations attenuate more rapidly than do low frequency vibrations motivated the development of a novel scheme in which the resonant excitation of coupled bending and lateral vibrations is applied to a cantilever beam. Switching times are determined using time-frequency analysis of modal responses. A smoothing function was applied to alleviate the effects of high-frequency oscillations during the switching control transition in order to facilitate the suppression of bending mode vibrations. Algorithms for proportional derivative (PD) control and positive position feedback (PPF) control can be tailored specifically for the target vibration modes and implemented in a variety of switching control schemes. The vibration responses induced by various switching control schemes was analyzed in order to derive appropriate control parameters for the development of an efficient switching control system aimed at suppressing multimodal vibrations. Experiment results demonstrate the effectiveness of the proposed piezoelectric electrode configuration in suppressing lateral mode vibrations. The proposed switching control system also proved highly satisfactory in suppressing vibrations in a system subject to simultaneous bending mode excitation.

Hydrodynamic Tweezers: Trapping and Transportation in Microscale Using Vortex Induced by Oscillation of a Single Piezoelectric Actuator.

The demand for a harmless noncontact trapping and transportation method in manipulation and measurement of biological micro objects waits to be met. In this paper, a novel micromanipulation method named “Hydrodynamic Tweezers” using the vortex induced by oscillating a single piezoelectric actuator is introduced. The piezoelectric actuator is set between a micropipette and a copper beam. Oscillating the actuator at a certain frequency causes the resonance of the copper beam and extend 1D straight oscillation of the piezoelectric actuator to 2D circular oscillation of the micropipette, which induces a micro vortex after putting the micropipette into fluid. The induced vortex featuring low pressure in its core area can trap the object nearby. A robotic micromanipulator is utilized to transport the trapped objects together with the micropipette. Experiments of trapping and transportation microbeads are carried out to characterize the key parameters. The results show that the trapping force can be controlled by adjusting peak-peak voltage of the sinusoidal voltage input into the piezoelectric actuator.

A decoupled flexure-based rotary micropositioning stage with compact size

This paper presents the design and analysis of a novel compact flexure-based rotary micropositioning stage driven by piezoelectric actuator. The developed stage possesses a double four-bar rotary mechanism with rotational symmetric configuration and totally kinematic decoupling, which can convert the linear motion of the piezoelectric actuator into the pure rotational motion, significantly minimizing the parasitic error at the rotation center. Based on the configuration, a single piezoelectric actuator is employed to drive the stage, avoiding actuator redundancy and large configuration size. Meanwhile, we introduce a compliant rotational guiding mechanism to enhance the rotational stiffness and dynamics of the stage. Analytical modeling and finite element analysis are adopted to facilitate the design of dimension. Finally, a prototype of the stage is manufactured and tested, which is capable of a rotational angle of [Formula: see text] with the first natural frequency of 430 Hz, whilst the well-constrained maximum center shift along the X- and Y-axis are 0.29 µm and 0.12 µm, respectively, indicating good decoupling capability. Furthermore, the compact size of [Formula: see text] is beneficial for limited working space.

Simultaneous Displacement and Force Estimation of Piezoelectric Stack Actuators Using Charge and Voltage Measurements

This article is devoted to simultaneous displacement and force self-sensing using a single piezoelectric stack actuator. Values of displacement and force are estimated from measurements of charge and applied voltage. To calibrate the self-sensing algorithm, a parameter identification procedure is presented that accounts for hysteresis under varying displacement and force conditions using a standard Prandtl–Ishlinskii hysteresis operator. Quasi-static validation experiments are carried out on a custom-built test rig that shows low average estimation errors of $0.5 \%$ and $-0.4\%$ with standard deviations of $2.7\%$ and $3.1\%$ in displacement and force, respectively.

Development of a radial-flow multiple magnetically coupled fan system with one piezoelectric actuator

In recent years, piezoelectric fans and their feasibility for use in cooling electronic devices have been widely studied. However, there are few studies that address using a single piezoelectric actuator to generate radial air flow. In this study, a radial-flow multiple fan system (RMFS) was developed for the thermal management of high power LEDs. This system only used one piezoelectric actuator and a magnetic repulsive force to activate up to 20 fans, which featured low power consumption and a large cooling area. The RMFS was mounted in a circular heat sink to evaluate its thermal performance. To find the optimal design for the RMFS, the influence of some geometric parameters was investigated. The performance of different designs was compared with a commercially available axial fan. The results showed that design E had the best thermal performance among the designs because of its relatively large frequency and amplitude. The thermal resistance and percentage improvement under a 35W heat flux were 0.86K/W and 36.9%, respectively. In addition, a coefficient of performance (COP) was defined. The COP of design E was approximately 3.7 times that of the rotary fan. For the power consumption aspect, the RMFS is more efficient than the rotary fan.