Linear Piezoelectric Motor Research Articles

Piezoelectric Linear Motors with Alternating Action for Motion Servo System of Probe Station

The development of a piezoelectric linear motor is presented in this paper, based on the principle of alternating motion, to meet the acting stroke and accuracy requirements for the probe station’s motion servo system. By partitioning the stator into tangential and normal components, two tangential actuators are affixed to the base, while two normal actuators are fixed on the preloading mechanism, thereby proposing a novel approach for connecting the stator and base. First, the construction and the working principle of the motor were introduced. Subsequently, the motor’s major components were designed through finite element simulation, followed by modeling the motor dynamics and deriving its displacement transfer function. Finally, an experimental prototype was fabricated, and a prototype test system was constructed. The driving method can realize a large stroke operation at a low frequency. The minimum operating frequency of the motor is 1 Hz, the minimum step is 12.55 μm, and the stroke is 105 mm. The study results will promote the development of high-performance probe systems.

A Novel Four legged linear piezoelectric inchworm motor with high thrust force

A Novel Four legged linear piezoelectric inchworm motor with high thrust force

A novel high energy density single-phase linear piezoelectric motor: design and experiment

The circuit simplification and simple structure of piezoelectric motor have become a major trend at present. Therefore, a novel, miniaturized, single-phase driven piezoelectric motor is proposed. The suggested piezoelectric motor employs a bending vibration mode of the first order, which is inspired by the motion patterns of fish tail fins. First, the motor’s operational principle and structure are explained. By analyzing the relationship between the working frequency and amplitude of the motor and the output power, the key parameters of the motor are determined, and the structure size of the motor is calculated. Next, the FEM model of the stator is utilized to conduct transient analysis in order to examine the movement path of the driving foot. Symmetrical right-diagonal or left-diagonal motions are formed by the driving foot during the first bending vibration, creating oblique elliptical movements. Finally, a prototype is made and its vibration and mechanical characteristics are tested. At a frequency of 15.6 kHz, the motor’s highest speed without any load is measured at 31.2 mm/s. Both forward and backward performance is identical. When the motor is supplied with a voltage of 140 Vpp and a preload of 2 N, it achieves a moving speed of 4.2 mm/s at 15.6 kHz, with an output thrust of around 0.9 N.

Research on variable stiffness asymmetrical resonant linear piezoelectric actuator based on multi-modal drive

In this paper, a linear piezoelectric motor with variable stiffness and asymmetric resonance is proposed, which is driven by a single harmonic signal. Working in the resonant state improve the output performance of the motor. Motor control is relatively simple and can realize reverse movement under the driving of second-order single harmonic signal. At the same time, the new motor can obtain different operating speed and step distance by changing the clamping position in front and back to meet the requirements of different loads and different working conditions and has strong applicability. By experiment, the first-order optimal operating frequency of the motor prototype at three different stiffness adjustment positions is 88 Hz, 90 Hz and 92 Hz respectively. Under the excitation of 240 Vp–p first-order resonance signal, the corresponding output speed of the motor prototype is 16.116 mm s−1, 20.457 mm s−1 and 25.015 mm s−1 respectively, and the corresponding displacement resolution is 0.18 mm, 0.22 mm and 0.27 mm respectively. When the stiffness adjustment positions is 2 mm, the maximum load of the motor prototype reaches 450 g. The second-order optimal operating frequency at the stiffness adjustment positions 1 mm is 601 Hz. Under the excitation of a 240 Vp–p second-order resonant signal, the reverse output speed of the motor prototype is 13.126 mm s−1, and the corresponding displacement resolution is 0.02 mm.

Design and experimental analysis of a high force piezoelectric linear motor

In this paper, the design and experimental analysis of a piezo-motor for applications requiring compact size, high blocking and driving forces are presented. Mechanical design addresses difficulties associated with high integration flexibility and high blocking force for the motor. The technology is inspired from a real inchworm motion and is based on Piezoelectric Actuators (PAs). The proposed Inchworm Motor (IM) consists of an extending mechanism (EM) and two doubled clamping mechanisms (CMs). Theoretically and by using Finite Element Analysis (FEA), the CM is designed in order to obtain high clamping forces between rotor and stator (2500N), while the EM is designed for large displacement (free stroke of 0.01mm) and high force (500N) using PAs. Practically and by using a preliminary low power supply (80V, 1Hz), the working principle of the motor is validated under testing conditions of 300N as a clamping force and 5N as a driving force. The fabricated IM achieves speed of 2.25μm/s. Experimental methods for verifying the theoretical force, calibrating the pre-stressing force and measuring the friction coefficient between the stator and the rotor are proposed. A motor with a weight of 78g and dimensions of 100mm×16mm×7mm ensures full clamping ability when not electrically activated.

Low-voltage driving linear piezoelectric motors having textured sliders of surface multi-connected vesicle-like microarray

Friction behavior and serious wear of the stator/slider pair are critical to restrict the development and commercialization of standing-wave linear ultrasonic motors. Owing to the effective friction regulation of laser surface microtextures, a multi-connected vesicle-like microarray consisting of the micropits and microgrooves was prepared on the slider surface. Finite element analysis at the microscale showed the proposed micro-textures were prone to cause the stator tip to sink, resulting in an increase of horizontal impact effect of ultrasonic vibration and the alternately regulating of static-dynamic friction boundary, which enhances the tangential force and improves the driving effect. The experimental results approved that the composite microtextures combining the pits of 100 μm and the grooves of 50 μm are positive for friction drive and output performance enhancement. Specifically, the output power of the low-voltage driving linear piezoelectric motor with the complex texturing array is 66% higher than that of non-textured ones. This study provides a reliable approach to enhancing the friction-driving performance and operation stability of piezoelectric motors or actuators.

Transient measurement of mechatronic multi-parameters and kinetics performances for linear piezoelectric motors

Due to the time-dependent correlations, the measurement and characterization of electronic and mechanical parameters are critical for linear piezoelectric ultrasonic motors (USMs) during the running process. This study constructed a homemade system to measure the electromechanical multi-parameters and kinetics performances agilely, transiently, and synchronously. The principles and structures of the test system were demonstrated based on virtual instrument technology. A signal conditioning circuit is designed and used for physical signal processing, A/D conversion, and transmission. The difference in resonant frequencies was discovered for the synchronization acquisition of mechatronic parameters, and the instantaneous characteristics of electromechanical parameters for SWUM (e.g., driving voltage, input current, thrust force, and speed during the start-up and power-off process) were established based on the experimental data. This study is significant for the measurement/evaluation of the dynamic and transient performances of linear piezoelectric motors and actuators.

Low-temperature sintered PMnS–PZT multilayer-ceramic for nano-step piezomotor application

Multilayer piezoceramic featured with low driving voltage and large generation force is a basic core component of piezoelectric motors. It has been found that Pb(Mn1/3Sb2/3)O3–Pb(Zr,Ti)O3 (PMnS–PZT) piezoceramic is a powerful system as it simultaneously exhibits a large piezoelectric coefficient (d) and a high mechanical quality factor (Q). However, a quite high sintering temperature (> 1200 ℃) is required, which limits the low-temperature co-firing preparation of the PMnS–PZT multilayer ceramic. In this work, we report a high-performance PMnS–PZT multilayer ceramic using Li2CO3 as a sintering aid and a linear piezoelectric motor based on the multilayer ceramic. The investigations show that a 0.4 wt% Li2CO3-modified PMnS–PZT ceramic sintered at 980 ℃ exhibits excellent ferroelectric, piezoelectric and electromechanical coupling properties. Furthermore, a 12-layer structured linear piezomotor was fabricated based on the Li2CO3-modified PMnS–PZT multilayer ceramic (with Ag/Pd internal electrodes), which shows a superhigh unit volume driving force in comparison with the previously reported piezoelectric motors and a 50 nm step resolution. The obtained results indicated that Li2CO3-modified PMnS–PZT ceramic and its multilayer structure have great potential for high-power device applications.

A Rotary-Linear Ultrasonic Motor Using MnO2-Doped (Ba0.97Ca0.03)(Ti0.96Sn0.005Hf0.035)O3 Lead-Free Piezoelectric Ceramics with Improved Curie Temperature and Temperature Stability

In this work, a cylindrical lead-free rotary-linear ultrasonic motor was attached to piezoelectric plates of MnO2-doped (Ba0.97Ca0.03)(Ti0.96Sn0.005Hf0.035)O3 ceramics using the first bending vibration to pull a thread output shaft of the interior of a stator. The effect of the proposed ceramics’ d33 and Qm values are the key factors for ultrasonic motors. Therefore, MnO2-doped (Ba0.97Ca0.03)(Ti0.96Sn0.005Hf0.035)O3 lead-free piezoelectric ceramics with high values of d33 = 230 pC/N, Qm = 340.8 and a good temperature stability of their dielectric and piezoelectric properties are suitable for application to linear piezoelectric motors. The structure of the linear piezoelectric motor was simulated and fabricated by Finite Element Analysis. The characteristics of linear piezoelectric motors were also studied. The output characteristics of the lead-free piezoelectric motor were a left-pull velocity = 3.21 mm/s, a right-pull velocity = 3.39 mm/s, an up-pull velocity = 2.56 mm/s and a force >2 N at 39.09 kHz for an input voltage of approximately 200 Vp-p (peak to peak). These results are comparable to those for a lead-based piezoelectric motor that uses PZT-4 ceramics. The proposed lead-free piezoelectric motors were successfully fabricated and used to pull a 0.5 mL commercial insulin syringe.

Wear evaluation model of a linear piezoelectric ultrasonic motor considering temperature effect

Ultrasonic motor relies on interface friction to drive the slider movement. During continuous operation, the contact surfaces between the stator and slider are worn, which will affect the performance and service life of the motor. A novel wear evaluation model considering temperature effect is established to estimate the remaining life and performance for a linear piezoelectric ultrasonic motor. The interactions of temperature with resonance frequency and material parameters are considered. The relationship between wear volume and preload as well as the variations of surface roughness parameters are taken into account. An experimental platform is built to identify the critical parameters and verify the accuracy of this model. The results show that the developed model can not only predict the temperature and service life, but also evaluate the performance of the motor, which can provide valuable guidance for motor design and optimization.

Bidirectional linear inertial impact piezoelectric motor with multimodal resonance.

A new multimodal bidirectional linear inertial impact motor with bidirectional motion based on self-clamping control driven by a single-harmonic signal was designed and manufactured. By applying driving signals of different resonant frequencies to the piezoelectric plate of a piezoelectric motor combined with the unique structural design of the motor, the piezoelectric motor has multiple modes and has the ability of two-way movement. First, the overall structure of the motor is introduced, and its working principle and theoretical displacement characteristics are presented through the periodic motion diagram of the piezoelectric motor. Second, the simulation analysis is carried out to determine the working modal of the proposed motor with COMSOL5.2. Finally, a motor prototype is developed, and the accuracy of the working principle and the simulation analysis is verified through experimental tests. When the motor has no load, the driving voltage is 200Vp-p. The maximum speed when moving to the right reached 3.125 mm/s when the preload is 2 N, and the driving frequency is 96Hz. The maximum speed when moving to the left reached 4.301 mm/s when the preload is 4 N, and the driving frequency is 148Hz. In the load capacity test of the motor prototype, the maximum load of the piezoelectric motor prototype moving to the right and left can reach 0.4 and 0.6 N, respectively. Compared with similar inertial impact motors, the proposed motor achieves flexible control of driving and switching of two-way movement conveniently and has a certain driving ability.

Resonant-type inertial impact linear piezoelectric motor based on coupling of driving and clamping parts

A resonant-type inertial impact linear piezoelectric motor based on coupling of driving and clamping parts was designed and manufactured. The motor mainly includes stator (coupling of driving and clamping parts), mover (slider) and auxiliary parts. The driving part works in the resonant state under the excitation of single harmonic, which mainly realizes the function of reciprocating driving. Similarly, under the single harmonic driving, the clamping part also works in the resonant state to realize the clamping function. Through the coupling between the two parts of the stator, the mover is driven to move continuously in one direction. The inertial impact piezoelectric motor works in the resonant state because the driving and clamping parts work in the resonant state respectively. Compared with the traditional quasi-static inertial impact motor, this study novelly changes the working state of the inertial impact motor. Through the finite element simulation software COMSOL 5.2, the resonant frequency coupling of the driving and the clamping part is consistent. An experimental platform was built to verify the feasibility of the principle by testing the motor prototype. The experiment results show that: The maximum speed reaches 78 mm s−1 when the motor prototype is operated at the frequency of 810 Hz with a preload of 2 N and the working voltages of clamping and driving parts of motor were set at 80 and 220 Vp-p respectively. Meanwhile, the maximum load of the motor prototype can reach 5 N. The minimum resolution of the motor prototype is 6.379 μm.

One-dimensional traveling wave type linear piezoelectric moving platform driven by a new two-frequency two-mode excitation method

The traveling waves of linear traveling wave type piezoelectric motors are not easy to stabilize due to its finite boundary structure. The traditional two-mode excitation method is a method which can excite two modes to generate traveling waves in a finite structure. However, the drawback of the traditional method is that it does not allow for adjustment of the final output velocity. Also, this method is characterized by having low efficiency. The velocity of the generated traveling waves is constant unless the excited modes are changed. In this paper, we propose a novel method, called a two-frequency two-mode excitation method which uses a piezoelectric actuator to simultaneously excite two modes to generate traveling waves. The two frequencies chosen possess a ratio where the excited frequencies are close to two resonant modes. In addition, the two excited frequencies are simultaneously an integer ratio to a specific frequency and have a least one common multiple, as small as possible. This approach can generate stable traveling waves such that the velocity of the traveling waves can be adjusted by the two frequencies. Our theoretical predictions were validated by numerical calculations and experimental data. A Hilbert transform was used to optimize the traveling waves generated. A morphological opening was used to track the traveling wave trajectories. The obtained results show that this method can generate stable traveling waves where the wave velocity can be adjusted by mixing the frequency signals.

Non-resonant piezoelectric linear motor with alternating normal contact force.

A non-resonant piezoelectric linear motor with alternating normal contact force is developed to realize a piezoelectric linear motor with high precision, large stroke, and strong thrust. The motor employs four piezoelectric stacks to excite the non-resonant state vibration of two driving feet, which alternately push the mover to generate unidirectional motion. Through the analysis of the working principle of the motor, the structure of the motor is designed and manufactured. The test results show the feasibility of the motor. Furthermore, the operating results show that the flatness of the contact surface strongly affects the performance of the motor. The design criteria of the motor are proposed, thus providing a basis for the optimization of the motor.

Bidirectional motion characteristics of a single harmonic-driven self-clamping linear piezoelectric motor.

We propose a multimodal model to realize the bidirectional motion of a self-clamping linear piezoelectric motor driven by a single harmonic signal based on previous motor research. Compared with the previous version, only the characteristics of the drive signal need to be changed in the motor without changing any other conditions to excite multimode and achieve reverse movement. The finite element software COMSOL5.2 was used to simulate the mode of the motor. The prototype has a maximum output speed of 71.5 mm/s, a maximum traction of 0.9 N at a voltage of 220Vp-p, a frequency of 536Hz, and a preload of 2 N. The minimum resolution of 26.4 µm was achieved at no-load, a voltage of 120Vp-p, and a preload of 0 N.

Composite Data Driven-Based Adaptive Control for a Piezoelectric Linear Motor

Piezoelectric linear motors play an important role in ultraprecision manufacturing technology. However, the complex nonlinear relationship between the input and output of the piezoelectric linear motors limits their further application. In this article, to achieve precise motion control for a piezoelectric linear motor, a composite data-driven-based adaptive control method is proposed, consisting of a correction controller, model-free adaptive control (MFAC), and low pass filter. The proposed control method addresses the demand for a precise model of the piezoelectric linear motor and solely relies on the linear model and input–output measurement data. First, an experimental test is implemented to analyze the complex nonlinearity between the input and output signals of the controlled system, and a correction control is employed based on the dynamic linear sub-model of the piezoelectric linear motor to improve its dynamic and static characteristics. Then, to avoid the influence of unmodeled dynamics, such as inherent nonlinearity and external vibration, an MFAC is established as a feedback controller using data-driven technology. In addition, a low pass filter is incorporated into the feedback loop to eliminate high-frequency measurement noise in the system, thus improving the transient response of the MFAC method. Finally, the theoretical analysis of the error convergence is presented. The effectiveness of the proposed method is verified via comparisons with a correction control method, correction control-based digital sliding-mode control (DSMC) method, and correction control-based MFAC method. The experimental results indicate that the proposed control method is suitable for engineering applications. In particular, the root-mean-square error (RMSE) for the third-order S-curve tracking using the proposed is reduced by more than 15%, compared with the RMSEs for the cases with contrast control methods.

Design and Optimization of a Linear Piezoelectric Motor using Response Surface Method

Design and Optimization of a Linear Piezoelectric Motor using Response Surface Method

CNN-based CP-OCT sensor integrated with a subretinal injector for retinal boundary tracking and injection guidance.

.Significance: Subretinal injection is an effective way of delivering transplant genes and cells to treat many degenerative retinal diseases. However, the technique requires high-dexterity and microscale precision of experienced surgeons, who have to overcome the physiological hand tremor and limited visualization of the subretinal space.Aim: To automatically guide the axial motion of microsurgical tools (i.e., a subretinal injector) with microscale precision in real time using a fiber-optic common-path swept-source optical coherence tomography distal sensor.Approach: We propose, implement, and study real-time retinal boundary tracking of A-scan optical coherence tomography (OCT) images using a convolutional neural network (CNN) for automatic depth targeting of a selected retinal boundary for accurate subretinal injection guidance. A simplified 1D U-net is used for the retinal layer segmentation on A-scan OCT images. A Kalman filter, combining retinal boundary position measurement by CNN and velocity measurement by cross correlation between consecutive A-scan images, is applied to optimally estimate the retinal boundary position. Unwanted axial motions of the surgical tools are compensated by a piezoelectric linear motor based on the retinal boundary tracking.Results: CNN-based segmentation on A-scan OCT images achieves the mean unsigned error (MUE) of () using an ex vivo bovine retina model. GPU parallel computing allows real-time inference () and thus real-time retinal boundary tracking. Involuntary tremors, which include low-frequency draft in hundreds of micrometers and physiological tremors in tens of micrometers, are compensated effectively. The standard deviations of photoreceptor (PR) and choroid (CH) boundary positions get as low as when the depth targeting is activated.Conclusions: A CNN-based common-path OCT distal sensor successfully tracks retinal boundaries, especially the PR/CH boundary for subretinal injection, and automatically guides the tooltip’s axial position in real time. The microscale depth targeting accuracy of our system shows its promising possibility for clinical application.

Design and characterization of a thin linear ultrasonic motor for miniature focus systems

We present a miniature linear piezoelectric ultrasonic motor with a thin and hollow design, which can serve as an essential component of autofocusing features in next-generation camera modules. It consists of a thin square stator with a hole and an elastic cylindrical slider with a slit. The motor design, in which the slider inserted into the stator hole expands outward, enables a hollow structure for centering a lens and an optimal preload for enhancing the motor thrust force. In this study, we model the relationship between the dimensions and the preload statically to quantify the preload value and clarify the design methodology of the motor. After optimizing the preload empirically, we evaluate the fundamental characteristics experimentally. The stator with a side length of 4.5 mm and a thickness of less than 1 mm provides a thrust force of 12.9 mN that leads to a quick response, which is a requirement of autofocusing. Finally, the motor drive system with visual feedback control is used to demonstrate the positioning of an actual lens group in front of an image sensor to obtain clearer images.

Design of a Short-Beam Linear Traveling-Wave Piezoelectric Motor.

A straight short-beam linear piezoelectric motor constructed with two sets of ceramic actuators separated with the 1/4 wavelength interval is designed in this article. The piezoelectric ceramic actuators are fabricated in the whole body, which is driven by a two-phase circuit with the same amplitude but a phase difference of π /4. Traveling wave (TW) is formed by superimposing standing waves generated by each set of ceramic actuators. At the ends of the short beam, a wave-reduction mechanism with larger cross-sectional area is designed so that wave reflection is effectively diminished to preserve the TW. The currently developed short-beam linear piezoelectric motor is estimated, which can produce an ideal output speed of 169 mm/s while applying voltage of Vpp = 300 V at 45.49 kHz. Instead of operating as a stator to drive a carriage for example, the short-beam linear piezoelectric motor is implemented on a guide slider, and therefore, a linear piezoelectric motor stage is built. While driving the linear stage employed with a preload 300 GW and a friction coefficient of about 0.15, the propulsion force is measured about 4.8 N, the speed is about 56 mm/s, and the position resolution can achieve in the submicrometer scale.