Linear Piezoelectric Motor Research Articles

Development of an ultrasonic linear motor with ultra-positioning capability and four driving feet

This paper presents a novel linear piezoelectric motor which is suitable for rapid ultra-precision positioning. The finite element analysis (FEA) was applied for optimal design and further analysis, then experiments were conducted to investigate its performance. By changing the input signal, the proposed motor was found capable of working in the fast driving mode as well as in the precision positioning mode. When working in the fast driving mode, the motor acts as an ultrasonic motor with maximum no-load speed up to 181.2mm/s and maximum thrust of 1.7N at 200Vp-p. Also, when working in precision positioning mode, the motor can be regarded as a flexible hinge piezoelectric actuator with arbitrary motion in the range of 8μm. The measurable minimum output displacement was found to be 0.08μm, but theoretically, can be even smaller. More importantly, the motor can be quickly and accurately positioned in a large stroke.

Novel linear piezoelectric motor for precision position stage

Conventional servomotor and stepping motor face challenges in nanometer positioning stages due to the complex structure, motion transformation mechanism, and slow dynamic response, especially directly driven by linear motor. A new butterfly-shaped linear piezoelectric motor for linear motion is presented. A two-degree precision position stage driven by the proposed linear ultrasonic motor possesses a simple and compact configuration, which makes the system obtain shorter driving chain. Firstly, the working principle of the linear ultrasonic motor is analyzed. The oscillation orbits of two driving feet on the stator are produced successively by using the anti-symmetric and symmetric vibration modes of the piezoelectric composite structure, and the slider pressed on the driving feet can be propelled twice in only one vibration cycle. Then with the derivation of the dynamic equation of the piezoelectric actuator and transient response model, start-upstart-up and settling state characteristics of the proposed linear actuator is investigated theoretically and experimentally, and is applicable to evaluate step resolution of the precision platform driven by the actuator. Moreover the structure of the two-degree position stage system is described and a special precision displacement measurement system is built. Finally, the characteristics of the two-degree position stage are studied. In the closed-loop condition the positioning accuracy of plus or minus <0.5 μm is experimentally obtained for the stage propelled by the piezoelectric motor. A precision position stage based the proposed butterfly-shaped linear piezoelectric is theoretically and experimentally investigated.

Modeling and analysis of stick-slip motion in a linear piezoelectric ultrasonic motor considering ultrasonic oscillation effect

Piezoelectric ultrasonic motor is an electromechanical coupling system, which is driven by the interface friction between the stator and the rotor/slider. A novel friction model is developed to study the stick–slip motion in a linear piezoelectric ultrasonic motor using longitudinal and bending modes. In this model, the influence of the ultrasonic oscillation on the dynamic friction coefficient is taken into account, which is described by a friction law related to the vibration amplitude at the interface. In addition, the friction contact model involves intermittent separation non-linearity induced by the variable normal force, which can result in complex stick–slip–separation motion at the contact interface. Analytical transition criteria between stick and slip are established by using the switch model. Based on the developed model, numerical simulations are performed to analyze the force transmission between the stator and the slider involving stick–slip motion. A transformed phase plane is proposed to study various states of the contact interface (stick, slip and separation), on which slip–separation, stick–slip, stick–slip–separation, and pure stick motions are intuitively characterized. The influence of some input parameters on the stick–slip motion is analyzed. Furthermore, the low-voltage dead-zone behavior is clarified by stick motion.

Improvement of a rectangle-shape linear piezoelectric motor with four driving feet

To increase the mechanical output ability of a rectangle-shape linear piezoelectric motor with four feet, an improved motor is designed in this study. The improved motor inherits the basic structure of the previous one, but the structure dimensions are adjusted by widening the horizontal beam, shortening the length of the vertical beam׳s uniform part, increasing the length of the vertical horn, and changing the widths of the horns׳ tips. Modal analysis and transient analysis are developed to gain the vibration modes of the motor and the motion trajectories of the driving feet, respectively. After the fabrication of a prototype, its vibration characteristics and mechanical output ability are measured. Experiment results show that a maximum no-load speed of 621mm/s, a maximum thrust force of 11N, and a maximum power of 1.9W are achieved by the prototype. Comparison between the improved motor and the previous one verifies that this study accomplish the design intention of mechanical output ability improvement perfectly.

Manipulator Design and Operation for a Six-Degree-of-Freedom Handheld Tremor-Canceling Microsurgical Instrument.

This paper presents the design and actuation of a six-degree-of-freedom (6-DOF) manipulator for a handheld instrument, known as "Micron," which performs active tremor compensation during microsurgery. The design incorporates a Gough-Stewart platform based on piezoelectric linear motor, with a specified minimum workspace of a cylinder 4 mm long and 4 mm in diameter at the end-effector. Given the stall force of the motors and the loading typically encountered in vitreoretinal microsurgery, the dimensions of the manipulator are optimized to tolerate a transverse load of 0.2 N on a remote center of motion near the midpoint of the tool shaft. The optimization yields a base diameter of 23 mm and a height of 37 mm. The fully handheld instrument includes a custom-built optical tracking system for control feedback, and an ergonomic housing to serve as a handle. The manipulation performance was investigated in both clamped and handheld conditions. In positioning experiments with varying side loads, the manipulator tolerates side load up to 0.25 N while tracking a sinusoidal target trajectory with less than 20 μm error. Physiological hand tremor is reduced by about 90% in a pointing task, and error less than 25 μm is achieved in handheld circle-tracing.

Characterization of intracochlear rupture forces in fresh human cadaveric cochleae.

To develop a method to measure the forces required for a probe to translocate from the scala tympani (ST) to the scala vestibuli (SV) in fresh human cochleae. Translocation of cochlear implant electrodes from the ST to the SV may lead to suboptimal audiologic outcomes. Prior work investigating the rupture forces of human intracochlear membranes comes from a single study conducted on isolated ex vivo cadaveric specimens. Fresh (postmortem <120 h), nonfixed, never-frozen human temporal bones underwent preparation consisting of surgical isolation of the cochleae and exposure of the osseous spiral lamina, basilar membrane, and Reissner's membrane complex by removing bone covering the ST and the SV. Each isolated cochlea was mounted to a force sensor using an adjustable mounting platform. A 300-μm-diameter ball-tipped probe was attached to a piezoelectric linear motor and advanced at 1 mm/s from the ST to the SV while recording force from the load cell concurrent with video. Ten specimens were successfully exposed and analyzed. The range of rupture forces was 42 to 122 mN, with a mean of 88 mN. Nine of the 10 specimens failed via simple puncture, whereas one failed by being avulsed from its medial attachment. Using a novel technique, we report the forces required to translocate a model of an electrode from the ST to the SV. Correlation to human perceptual ability is necessary to determine if a surgeon can detect such translocation during cochlear implant surgery.

Dynamic Petri Fuzzy Cerebellar Model Articulation Controller Design for a Magnetic Levitation System and a Two-Axis Linear Piezoelectric Ceramic Motor Drive System

This brief aims to propose a more efficient control algorithm for a magnetic levitation system (MLS) and a two-axis linear piezoelectric ceramic motor (LPCM) drive system. A dynamic Petri fuzzy cerebellar (DPFC) model articulation controller is developed to allow control of the position of the metallic sphere of an MLS and the trajectory tracking of a two-axis LPCM drive system. In the DPFC, the concept of a Petri net and a fuzzy frame are incorporated into a cerebellar model articulation controller (CMAC), which alleviates the computational burden that accompanies the learning of parameters and enhances the fuzzy reasoning inference of CMACs. The supervised gradient-descent method is used to develop the online-training algorithm for the DPFC. To guarantee the convergence of trajectory tracking errors, analytical methods that use a discrete-type Lyapunov function are proposed for the DPFC. The experimental results demonstrate the effectiveness of the proposed DPFC for different experimental systems.

A Study on the Linear Piezoelectric Motor of Mode Shape

In this paper, we want to make a new type linear piezoelectric motor by mode shape coating or effective electrode surface coating. The mode shape is derived from the mechanical boundary conditions of the linear piezoelectric motor. We only have access to the first three modes of formas, the effective electrode surface coating basis, as well as with the linear piezoelectric motor of normal shape do comparison. Next, we will inspect their gain or axial velocity through theoretical analysis, simulation and experiment. According to the results of the theoretical analysis, we have found that the gain or axial velocity of the linear piezoelectric motors of mode shape is much larger than the linear piezoelectric motors of normal shape. However, according to the results of simulation and experiments, we have found that the gain or axial velocity of the linear piezoelectric motors of mode shape is much greater than the linear piezoelectric motors of normal shape, which is about 1.2 to 1.4 times. The linear piezoelectric motor of mode shape 3 has the fastest axial velocity, which is about -48 mm/s and 48 mm/s under conditions of 180 Vp-p driving voltage, 21.2 kHz driving frequency (the third vibration modal), 25 gw loading and the position of loading or mass at x = 5 mm & 45 mm respectively. And its axial velocity is about 1.4 times the linear piezoelectric motor of normal shape under the same conditions. Overall, the mode shape coating helps to enhance the gain or axial velocity of the linear piezoelectric motor.

A T-shape linear piezoelectric motor with single foot

A new T-shape piezoelectric motor using the hybrid of two orthogonal longitudinal vibrations is proposed in this work. Six pieces of PZT ceramic plates are bonded on the upside and downside surfaces of a T-shape duralumin alloy base respectively to form the proposed motor. Elliptical movement can be generated on the driving tip by applying sine and cosine voltages to the PZT elements. The horizontal displacement of the driving tip will push the runner while the vertical displacement can overcome the preload. Finite element method is used to accomplish the design and analysis process. The resonance frequencies of the two vibration modes are tuned to be close by modal analysis, while the motion trajectory of the driving tip is observed by transient analysis. After the fabrication of a prototype, the vibration characteristics and mechanical output ability are measured. The no-load speed and the maximum output thrust force of the proposed motor are tested to be 718mm/s and 3.5N under an exciting frequency of 53.1kHz. The proposed T-shape piezoelectric motor exhibits merits of simple structure, easy to realize miniaturization, easy to be fabricated, and high power-to-weight ratio.

Piezoelectric linear motor using resonant-type clamping based on harmonic vibration synthesis

A piezoelectric linear motor (PLM), which has a mechanism based on synchronized switching control, is composed mainly of a driving unit and a clamping unit. A resonant-type clamping (RTC) unit is developed to increase the working frequency of the motor. The developed RTC unit is a three-layer tuning fork structure with ten pieces of single-layer piezoelectric sheets as driving elements. The RTC unit was designed to have a resonant frequency ratio of 1:3:5 by deliberate design of the lengths and widths of each layer. A resonant-type quasi-square-shaped mechanical wave was obtained combined with the three vibration modes of those layers. A PLM prototype that utilized the developed RTC unit was fabricated and tested. The moving speed of the slider can reach up to 78.3mm/s at a driving voltage of 240Vp–p.

Development of a Piezoelectric-Actuated Drop-on-Demand Droplet Generator Using Adaptive Wavelet Neural Network Control Scheme

This paper presents the design, fabrication and control of a piezoelectric-type droplet generator which is applicable for on-line dispensing. The piezoelectric-actuated dispensing system consists of a linear piezoelectric motor (LPM) actuated table, a plastic syringe, a nozzle, a linear encoder and a PC-based control unit. Adaptive wavelet neural network (AWNN) control is applied to overcome nonlinear hysteresis inherited in the LPM. The adaptive learning rates are derived based on the Lyapunov stability theorem so that convergence of the tracking error can be assured. Unlike open-loop dispensing system, the system proposed can potentially generate droplets with high accuracy. Experimental verifications including regulating and tracking control are performed firstly to assure the reliability of the proposed control schemes. Real dispensing is then conducted to validate the feasibility of the piezoelectric-actuated drop-on-demand droplet generator. The results demonstrate that the proposed scheme works well in developing the piezoelectric-actuated drop-on-demand dispensing system.

Intelligent Control Using the Wavelet Fuzzy CMAC Backstepping Control System for Two-Axis Linear Piezoelectric Ceramic Motor Drive Systems

This study aims to propose a more efficient control algorithm to achieve precision trajectory tracking control for a two-axis linear piezoelectric ceramic motor (LPCM). Since the inherent nonlinear nature and cross-coupling effect of a two-axis LPCM, its accurate model is difficult to obtain; thus, an intelligent adaptive wavelet fuzzy cerebellar model articulation controller backstepping (AWFCB) control system is designed to achieve high precision trajectory tracking control for a two-axis LPCM drive system. A novel wavelet fuzzy cerebellar model articulation controller (CMAC) is proposed in this paper; in some special cases, it can be reduced to a fuzzy system, a fuzzy neural network, a wavelet fuzzy neural network, or a conventional CMAC. The developed wavelet fuzzy CMAC incorporates the wavelet decomposition property and a fuzzy CMAC fast learning ability; thus, it is used for the LPCM control. In the AWFCB control system, a wavelet fuzzy CMAC is used to imitate an ideal backstepping controller, and a smooth compensator is designed to eliminate the residual of the approximation error between the wavelet fuzzy CMAC and the ideal backstepping controller. In order to guarantee the convergence of the tracking error, analytical methods using the Lyapunov function are utilized to derive the adaptation laws to tune the parameters of the control system online. Thus, the stability of the two-axis LPCM control system can be guaranteed. Finally, the experimental results show the precision of the trajectory tracking using AWFCB control. Compared with PID control and adaptive fuzzy sliding-mode control, the AWFCB control can achieve tracking error reduction of about 80%~99% and 48%~97%, respectively.

High-order face-shear modes of relaxor-PbTiO3 crystals for piezoelectric motor applications

The face-shear vibration modes of [011] poled Zt ± 45° cut relaxor-PT crystals and their applications for linear piezoelectric motors were investigated. Unlike piezoelectric ceramics, the rotated crystal was found to exhibit asymmetric face-shear deformations, and its two high-order face-shear modes degraded into two non-isomorphic modes. As an application example, a standing wave ultrasonic linear motor (10 × 10 × 2 mm3) operating in high-order face-shear vibration modes was developed. The motor exhibits a large driving force (1.5 N) under a low driving voltage (22 Vpp). These findings could provide guidance for design of crystal resonance devices.

Miniaturization of a U-shape linear piezoelectric motor with double feet

A U-shape linear piezoelectric motor with double driving feet is proposed and tested. It adopts bonded-type structure to realize the miniaturization. Six pieces of PZT ceramic plates are bonded on a U-shape duralumin alloy base to form the motor. This structure makes it has simple fabrication and assemblage processes. The proposed motor produces elliptical movements on the two driving feet by the superimposing of longitudinal vibrations. The resonance frequencies of the two vibration modes are tuned to be close at about 54kHz. Transient analysis is developed to illustrate the movements of the driving feet. The vibration characteristics of a prototype are measured by a scanning laser Doppler vibrometer. The no-load speed and the maximum output thrust force of the prototype are tested to be 765mm/s and 7.3N, respectively. The weight of the miniaturized U-shape piezoelectric motor is about 0.026kg; its power density is about 6.4 times that of the previous one with bolt-clamped structure.

Piezoelektrik Bir Motorun ANSYS'de Dinamik Analizi

In this study, Piezolegs-LL1011A which is linear piezoelectric motor type has been selected as a model. After modelling has been done of this motor, modal and harmonic analysis of same motor have been obtained with finite element package program ANSYS. As a result of these analysis, natural frequency values have been obtained of Piezolegs motor. An appropriate frequency range for motion of drive tip is obtained for harmonic analysis. In according to applied forces, harmonic analysis is done and drive tip motion of motor is observed. © Afyon Kocatepe Universitesi

A Bonded-Type Linear Piezoelectric Motor with Four Feet

A bonded-type linear piezoelectric motor with four feet is proposed, designed, fabricated and tested. The proposed motor consists of one rectangle-type metal frame and eight pieces of PZT ceramics. The proposed motor works under two vibration modes, in which the vertical and horizontal displacements of the driving feet are generated respectively. Elliptical movements, which can push the runner into linear motion, are produced on the driving feet. The structure and operating principle of the proposed motor are introduced. Typical output of the prototype motor is no-load speed of 613 mm/s and maximum thrust force of 4.6 N.

A square-plate piezoelectric linear motor operating in two orthogonal and isomorphic face-diagonal-bending modes

We report a piezoelectric linear motor made of a single Pb(Zr,Ti)O3 square-plate, which operates in two orthogonal and isomorphic face-diagonal-bending modes to produce precision linear motion. A 15 × 15 × 2 mm prototype was fabricated, and the motor generated a driving force of up to 1.8 N and a speed of 170 mm/s under an applied voltage of 100 Vpp at the resonance frequency of 136.5 kHz. The motor shows such advantages as large driving force under relatively low driving voltage, simple structure, and stable motion because of its isomorphic face-diagonal-bending mode.

Design of a Kind of Non-Resonant Linear Piezoelectric Motor

A type of drive foot with displacement amplification was proposed based on analysis of the friction drive principle of the non-resonant linear piezoelectric motors. Firstly, the displacement amplification mechanism of the drive foot was carried on and the elliptical trajectory equation of the drive tip was deduced through the mechanism model of the drive foot. The optimization design of main structure parameters was conducted with finite element analysis software to analyze the influences of displacement amplification. The simulation results showed that the maximum magnification factor can be obtained when H(the thickness of flexible arm) is 0.8mm and θ (the flexible angle) is 12°. A linear piezoelectric motor prototype was designed and fabricated, the experimental results indicated that this kind of motor can run steadily in a wide range (the operation bandwidth is beyond 1kHz) and that the thrust can be 0.35N and the maximum velocity can be 2.5mm/s when the operation frequency is 4kHz and the operation voltage is 90V.

Vibration Characteristics Analysis for the Stator of Dynamic Friction Linear Piezoelectric Stack Motors

To improve the output performance of piezoelectric linear motors, researches was carried on the vibration characteristic for the stator of dynamic-friction type non-resonant linear piezoelectric motors. By analyzing the construction and working mechanism of the motor, longitudinal vibration model was established for the stator of motor. Then the vibration differential equation of the drive tip was deduced and longitudinal displacement functions were proposed. Further, the prototype was fabricated and investigated by experiments on the longitudinal displacement of drive tip under different excitation conditions. Experiment results proved the vibration characteristic theory of stator that the longitudinal amplitude of drive tip increases with excitation voltage. The maximum amplitude of drive tip is 0.85μm and the output force is 3 N on condition that the operation voltage is 90 V and the frequency is 1.6 kHz. The above studies can provide theoretical basis for performance optimization of motor and for structural optimization of stator.

Design of a Long Distance Unidirectional Piezoelectric Motor Based on Non-Resonant Inchworm Principle

The advantages of linear piezoelectric motor which has low velocity, large output force, non-electromagnetic disturbance and high response speed are concerned wildly in astronautic industry and manufactural industry. A unidirectional and linear piezoelectric motor has been designed based on these advantages. The stiffness and resonant frequencies of the clamping structure and driving structure are calculated by mathematic model. The characteristics of long distance, slow velocity and large output force are realized. This motor can be used in the equipment which needs long distance, small inertia, large driving force and disposable movement. The stiffness and resonant frequencies of clamping structure and driving structure, no-load characteristic and motion characteristics under different loads are tested in the experiment. The results of the stiffness satisfy the theoretical design. The no-load resonant frequencies are high and the maximum resonant frequency dwindles with increasing load.