Linear Piezoelectric Motor Research Articles

Modeling and Characterization of a Linear Piezomotor

This article presents the modeling and characterization of a new class of piezoelectric linear motor. The motor relies in its operation on a set of piezoelectric bimorphs which are sequentially activated to linearly move a drive rod along spring loaded rollers. Emphasis in this article is placed on studying the dynamic behavior of this class of piezoelectric motors, both theoretically and experimentally, in an effort to predict the piezomotor response to various loads and excitation schemes. To this end, a numerical model has been developed to simulate the dynamics of the piezoelectric bimorphs comprising the piezomotor. Friction between the bimorph elements and the drive rod are handled using an appropriate friction model. Experimental testing of the motor is carried out to validate the predictions of the theoretical model.

Micro–macro linear piezoelectric motor based on self-moving cell

This paper deals with the development of a piezoelectric linear motor that can control macro and micro movements. Concept of the motor is based on a self-moving cell, which consists of an elastic shell structure and a piezoelectric stack actuator. Three cells are connected in series and by activating piezoelectric actuators in these cells, macro movement can be achieved. Since these cells are fit into a guideway with interference, this motor can possess a high stall force and fail-safe lock. When one piezoelectric actuator is activated by open loop control with hysteresis compensation, micro movement can be obtained. Design of self-moving cell structure, fabrication, and control of the motor for macro and micro movements are explained. The maximum moving velocity of 1.05 mm/s and the maximum force of 4.3 N were observed. The possibility of nano scale movement was demonstrated by taking into account the hysteresis compensation of the piezoelectric actuator.

Design, operation, and motion characteristics of a precise piezoelectric linear motor

Abstract This paper presents the design, operation, and motion characteristics of a precise piezoelectric motor for linear translation. The motor is compact, thermally stable, ultra-high vacuum compatible, and suitable for applications requiring fine resolution over millimeter-long travel ranges. Inside the motor, a translating alumina prism is symmetrically constrained within a stationary structure by a compliant suspension that preloads six shear-mode piezoelectric actuators against flat surfaces on the prism. A single step is achieved by sequentially sliding each piezoelectric actuator backward along the prism’s surfaces and then simultaneously moving all actuators forward. Many steps are repeated at 60 Hz for longer translations. Experiments indicate that: the step size is adjustable between 5 nm and 225 nm, the motor can reach speeds of 13.5 μ m/s, the step size is highly uniform with a standard deviation of about 1.2 nm, error motion in the direction orthogonal to the translation is about 800 nm peak-to-valley, and the thermal stability is better than 40 nm/ ° C.

A linear piezo-electric ultrasonic motor using a single flexural vibrating bar for electro-discharge system industrial applications

This paper provides the development process of a linear piezo-electric ultrasonic motor using a single flexural vibrating bar. The process covers the design methodology, conceptual design, basic configuration, modelling and analysis, principle of operation, motor structure, experimental examination and evaluation of the main characteristics of the motor. The motor comprises three main parts: the stator, rotor and sliding element. The mechanism concept of the developed motor is based on creating elliptical motions of surface points generated by superposition of longitudinal and bending vibration modes of oscillating structures. Pressing the stator against the driving tip, the microscopic motions are transferred into a rotary motion then into linear motion through the friction between parts of the motor. The developed motor provides a linear motion and can be driven with common droving system with electrical signal of invariable frequency. Modelling using finite element analysis, mechanism and design of the component of the developed prototype are presented in this paper. The essential experimental test to implement the motor in electro-discharge system industrial application was carried out, and the initial results show that the developed prototype is able to provide a reversible directional of motion, no-load travelling speed equal to 28 mm/s, maximum load of 0.78 N, a resolution <50 μm and a dynamic response <10 ms.

Multilayer piezoelectric linear ultrasonic motor for camera module

Piezoelectric linear ultrasonic motors have been widely studied for auto focusing devices of digital cameras and cellular phones due to their simple structure. A piezoelectric motor operated at low voltages, not achievable using bulk piezoelectrics, is required for the camera module of cellular phone. In this study, a tiny piezoelectric linear motor was fabricated and its dynamic properties at low voltages were analyzed. To reduce the driving voltage, thin multilayer ceramics fabricated by a tape casting method were applied to the motor. The proper number of layers of the piezoelectric element was determined by ATILA simulation program. As a result of the simulation, the largest displacement of the shaft was observed at 21 layers. Characteristics of the motor were analyzed with respect to applied voltages and frictional forces between the mobile element and shaft. Velocity and force of the motor increased with increasing applied voltage. The motor exhibited a velocity of 10.9 mm/s and a thrust force of 110 mN at a frictional force of 62.5 mN and an applied voltage of 10 Vp-p.

Piezoelectric linear motor with unimorph structure by co-extrusion process

A new piezoelectric linear motor was developed using a ring-shaped, unimorph stator composed of a piezoelectric active layer (0.3PZN–0.7PZT/Mn) and a conductive passive layer (0.3PZN–0.7PZT/Mn/Ag). The stator was prepared by co-extrusion followed by the thermoplastic green machining (TGM) process. After co-extruding the piezoelectrically active and passive layers together, they were machined into a ring shape and then sintered at 930 °C for 4 h. The stator was poled in the thickness direction and operated in radial vibration mode. A glass rod was used as the moving shaft. When a saw-tooth electric field was applied, the shaft moved linearly as a result of the stator's bending motion. When an inverted saw-tooth electric potential was applied, the shaft moved linearly in the opposite direction. The velocity of the piezoelectric linear motor was about 4 mm/s at an applied voltage of 80 V p–p and a resonance frequency of 36.5 kHz.

Adaptive growing-and-pruning neural network control for a linear piezoelectric ceramic motor

In this paper, an adaptive growing-and-pruning neural network control (AGPNNC) system is developed for a linear piezoelectric ceramic motor. The AGPNNC system is composed of a neural controller and a robust controller. The neural controller uses a self-constructing neural network (SCNN) to mimic an ideal computation controller, and the robust controller is designed to achieve L 2 tracking performance with desired attenuation level. If the approximation performance of the SCNN is inadequate, the SCNN can create new hidden neurons to increase learning ability. If the hidden neuron of the SCNN is insignificant, it should be removed to reduce computation loading; otherwise, if the hidden neuron of the SCNN is significant, it should be retained. Moreover, the adaptive laws of controller parameters are derived in the sense of Lyapunov function and Barbalat's lemma; so the system stability can be guaranteed. Finally, experimental results show that a perfect tracking response can be achieved using the self-constructing network mechanism and the on-line parameter-learning algorithm.

Comparison of Voltage-Source Resonant Driving Schemes for a Linear Piezoelectric Ceramic Motor

Linear piezoelectric actuators are innovative manipulators that have shown a high potential in applications requiring operation within the submicrometer or even the nanometer range. The driving principle of a linear piezoelectric ceramic motor (LPCM) is based on the ultrasonic vibration force of piezoelectric ceramic elements and mechanical frictional force. Therefore, its dynamic model is complex, and the motor parameters are time varying due to increasing temperature and changing motor drive operating conditions, so that it is difficult to design a suitable driving strategy for the LPCM. This paper presents a comparative study of three voltage-source resonant driving schemes, including an inductance-capacitance (LC) resonant inverter, an .LLCC-resonant inverter, and an LC-resonant inverter with energy feedback for the LPCM. The effectiveness of the reported driving strategies is verified by numerical analyses and experimental results under the variation of loads. By way of experimental validation, the newly designed -LC-resonant inverter with energy feedback for driving the LPCM possesses good performances of high voltage gain and invariant output characteristic under different operating conditions.

Development of Lyapunov-Based Genetic Algorithm Control for Linear Piezoelectric Ceramic Motor Drive

In general, the role of genetic algorithm (GA) is operated offline as a minor compensator or tuner in the control engineering because the systematic design and the latent stability problem of a GA-based control scheme are required to be solved. This paper originally designs a Lyapunov-based GA control (LGAC) scheme, and it applies for a practical control engineering example of the online motion control of a linear piezoelectric ceramic motor driven by a hybrid resonant inverter. In this control scheme, a GA control system via backstepping design technique is utilized to be the major controller, and adaptation laws derived from Lyapunov stability analyses are manipulated to adjust appropriate evolutionary steps. As a result, the system stability can be guaranteed directly without strict constraint conditions and detailed system knowledge. The effectiveness of the proposed drive and control system is verified by experimental results in the presence of uncertainties. From the measured results, the LGAC system performs superior high-precision motion control under wide operation range than conventional backstepping control system.

Traveling-wave piezoelectric linear motor. I. The stator design

A new type of piezoelectric linear motor incorporating a traveling wave has been developed. The linear motor is comprised of a stator and a carriage. The stator design, which consists of a meander-line structure and gear teeth mounted on the meander-line structure, is the focus of this article. The meander-line structure is constructed with bimorph actuators arranged in a line. These actuators are driven by two phased sets of alternating current (ac) in order to generate a traveling wave. The traveling wave is transferred to the gear teeth, by which the carriage is driven. Modeling of the stator is derived by use of a strain energy method. The performance of various materials is evaluated by analytical and experimental methods. The analytical and the experimental results are quite approximate. Modal analysis is investigated using ANSYS. Appropriate modes associated with ultrasonic levels of resonant frequency are selected to obtain desired motion and to enhance the output performance. Surface speed for various applied input voltage are studied and indicate a nearly linear relationship. The stator in combination with the carriage makes up the linear motor.

Traveling-wave piezoelectric linear motor. II. Experiment and performance evaluation

This article continues the discussion of a traveling-wave piezoelectric linear motor. Part I of this article dealt with the design and analysis of the stator of a traveling-wave piezoelectric linear motor. In this part, the discussion focuses on the structure and modeling of the contact layer and the carriage. In addition, the performance analysis and evaluation of the linear motor also are dealt with in this study. The traveling wave is created by stator, which is constructed by a series of bimorph actuators arranged in a line and connected to form a meander-line structure. Analytical and experimental results of the performance are presented and shown to be almost in agreement. Power losses due to friction and transmission are studied and found to be significant. Compared with other types of linear motors, the motor in this study is capable of supporting heavier loads and provides a larger thrust force.

Design of Total Sliding-Mode-Based Genetic Algorithm Control for Hybrid Resonant-Driven Linear Piezoelectric Ceramic Motor

This study presents a total sliding-mode-based genetic algorithm control (TSGAC) system for a linear piezoelectric ceramic motor (LPCM) driven by a newly designed hybrid resonant inverter. First, the motor configuration and driving circuit of an LPCM are introduced, and its hypothetical dynamic model is represented by a nonlinear function with unknown system parameters. In the hybrid resonant drive system, it has the merits of the high voltage gain from a parallel-resonant current source, and the invariant output characteristic from a two-inductance two-capacitance resonant driving circuit. Since the dynamic characteristics and motor parameters of the LPCM are highly nonlinear and time varying, a TSGAC system is therefore investigated based on direction-based genetic algorithm with the spirit of total sliding-mode control (TSC) and fuzzy-based evolutionary procedure to achieve high-precision position control under a wide operation range. In this control scheme, a GAC system is utilized to be the major controller, and the stability can be indirectly ensured by the concept of TSC without strict constraints and detailed system knowledge. In addition, the effectiveness of the proposed drive and control system is verified by numerical simulations and experimental results in the presence of uncertainties

Piezoelectric motor and method of exciting an ultrasonic traveling wave to drive the motor

A rotary ultrasonic piezoelectric motor is provided and a method of exciting a flexure traveling wave to drive the motor. The motor includes a stator having a piezoelectric ceramic disc polarized in the radial direction and bounded by a top electrode and a segmented bottom electrode. The motor also includes a power source for applying two pairs of alternating voltages to the bottom electrode segments to excite a shear-shear mode vibration in the stator, resulting in a shear-shear mode flexure traveling wave in the stator. The motor further includes a rotor operatively connected to the stator, and the stator is driven to rotate through a frictional force between the rotor and the stator due to the traveling wave deformation of the stator. A linear ultrasonic piezoelectric motor and method of exciting a flexure traveling wave to linearly drive the motor is provided. The motor includes a stator having a rectangular piezoelectric ceramic plate that is polarized in the longitudinal direction. The motor also includes a power source for applying two pairs of alternating voltages to the bottom electrode segments to excite a shear-shear mode vibration in the stator, resulting in a shear-shear mode flexure traveling wave in the stator. The motor further includes a slider operatively connected to the stator, and the stator is driven to move linearly through a frictional force between the slider and the stator due to the traveling wave deformation of the stator.

A study on the friction and thrust force of the shaft and mobile element in the impact typed piezoelectric ultrasonic linear motor

Recently, a novel tiny piezoelectric ultrasonic linear motor driven by impact force which converts a radial mode vibration into a longitudinal one was developed for camera optical modules. This tiny piezoelectric motor consists of a shaft, mobile element and piezoelectric transducer. In this work, the frictional properties of the interface between the shaft and mobile element were investigated according to their respective materials. Five types of materials were used for the shaft, viz. stainless steel coated with DLC (Diamond like carbon) and PTFE (Polytetrafluoroethylene), uncoated stainless steel, Pyrex and Graphite. Bakelite and stainless steel (SUS) were used for the mobile elements. It was found that two combinations, namely Pyrex glass or stainless steel for the shaft and stainless steel for the mobile element, exhibited good dynamic behaviors in a tiny piezoelectric ultrasonic linear motor, which was newly developed based on operating concepts based on Newton’s law.

Analysis of driving mechanism for tiny piezoelectric linear motor

Recently, a tiny piezoelectric linear motor using a vibration mode of the transducer has been invented. The motor consists of a shaft, mobile element, and piezoelectric transducer using a piezoelectric radial mode bimorph disk. The fringe of the bimorph disk is fixed firmly which means this area has no degree of freedom. Therefore, the radial mode of the transducer transfers to the flexure mode. The mobile elements move along the Pyrex shaft by the impact force generated by the flexure mode of the piezoelectric transducer. The motors are operated at their resonant frequencies. The dynamic properties of the motor have been intensively measured and analyzed according to the applied voltage waveforms at the resonant frequencies. As the sawtooth and rectangular voltage waveforms are applied, the velocity, the thrust force, and the velocity dependence of the mobile position are measured. The dynamic characteristics are also analyzed within a period of each wave using laser vibrometer. The velocity of the mobile is moderately constant along the shaft. The better dynamic characteristics are obtained in the case of applying the rectangular waveform.

Intelligent compensation of friction, ripple, and hysteresis via a regulated chatter

Abstract In this paper, a hybrid control scheme utilizing a PID feedback control with an additional regulated chatter signal is developed to compensate motion impeding influences such as the effects due to friction, force ripples, and hysteresis in linear piezoelectric motor. The regulated chatter signal is a pulse sequence superimposed on the PID control signal. It has a fixed amplitude, and a pulse width regulated via iterative learning control. As such, the scheme is expected to be useful for applications involving iterative motion sequences. An analysis of the closed-loop performance is presented in the paper. Simulation and experimental results are also furnished to demonstrate that the proposed control scheme can reduce tracking errors significantly.

Piezoelectric linear motor concepts based on coupling of longitudinal vibrations

Classically, rotary motors with gears and spindle mechanisms are used to achieve translatory motion. In means of miniaturization and weight reduction piezoelectric linear motors are of interest. Several ultrasonic linear motors found in literature base on the use of two different vibration modes. Most often flexural and longitudinal modes are combined to achieve an elliptic micro-motion of surface points. This micro-motion is converted to direct linear (or translatory) motion of a driven slider. To gain high amplitudes of the micro-motion and thus having a powerful motor, the ultrasonic vibrator should be driven near the eigenfrequency of its modes. Additionally, low mechanical and electrical losses lead to increased efficiency and large amplitude magnification in resonance. This demands a geometrical design that fits the eigenfrequencies of the two different modes. A frequency-deviation of only a few percent leads to non-acceptable disturbance of the elliptical motion. Thus, the mechanical design of the vibrators has to be done very carefully. Within this contribution we discuss different motor designs based on the coupling of two the same longitudinal vibrations within one structure to generate an elliptic motion of surface points. Different concepts based on piezoelectric plates and Langevin transducers are compared. Benefits and drawbacks against the combination of longitudinal and bending modes will be discussed. Numerical results of the stator vibration as well as motor characteristics are validated by measurements on different prototypes.

Adaptive grey control for hybrid resonant driving linear piezoelectric ceramic motor

This paper presents an adaptive grey control (AGC) system for a linear piezoelectric ceramic motor (LPCM) driven by a newly designed hybrid resonant inverter. First, the motor configuration and the driving circuit of an LPCM are introduced, and its hypothetical dynamic model is described briefly. The hybrid resonant drive system has the merits of high voltage gain from a parallel resonant current source and the invariant output characteristic from a two-inductance two-capacitance (LLCC) resonant driving circuit. Since the dynamic characteristics and motor parameters of the LPCM are highly nonlinear and time varying, an AGC system is therefore investigated based on the principle of computed torque control and grey method to achieve high-precision position control under wide operation range. In this control system, a grey uncertainty predictor is utilized to estimate the lumped uncertainty on line to relax the requirement of the unknown uncertainty in the design of a computed torque position controller. In addition, the effectiveness of the proposed drive and control system is verified by numerical simulations and experimental results in the presence of uncertainties.

Supervisory control for linear piezoelectric ceramic motor drive using genetic algorithm

This paper presents a supervisory genetic algorithm (SGA) control system for a linear piezoelectric ceramic motor (LPCM) driven by a two-inductance two-capacitance resonant driving circuit. First, the motor configuration and driving circuit of an LPCM are introduced, and its hypothetical dynamic model is described briefly. Since the dynamic characteristics and motor parameters of the LPCM are highly nonlinear and time varying, an SGA control system is therefore investigated to achieve high-precision position control. The proposed SGA control system is composed of two parts. One is a GA control that is utilized to search an optimum control effort online via gradient descent training process, and the other is a supervisory control to stabilize the system states around a predefined bound region. Compared with conventional GA control systems, the proposed control scheme possesses the salient advantages of simple structure, fewer executing time, and good self-organizing properties. The effectiveness of the proposed driving circuit and control system is verified with numerical simulations and hardware experiments under the occurrence of uncertainties. In addition, the advantages of the proposed control scheme are indicated in comparison with a traditional integral-proportional position-control system.

Linear piezoelectric ultrasonic motor

The present invention relates to a linear motor which draws its operating power from ultrasonic vibration above the frequency of 20 kHz which is generated by piezoelectric ceramic. More particularly, the invention relates to a linear piezoelectric ultrasonic motor which linearly operates a slider due to a frictional force generated by applying sinusoidal electric field with a 90 degree phase difference to a pair of piezoelectric ceramic. This causes an elliptical mechanical vibration on a shaking beam which is connected to the piezoelectric ceramic.