Piezoelectric Motor Research Articles

A practical application of sliding mode control in the motion control of a high precision piezoelectric motor

A practical application of sliding mode control in the motion control of a high precision piezoelectric motor

Comprehensive numerical characterization of a piezoelectric composite with hollow metallic inclusions using an adaptable random representative volume

This paper investigates a piezoelectric composite made up of a piezoceramic matrix with irregularly scattered random-sized hollow metal inclusions. This composite can be produced using a combination of porous ceramic fabrication methods and microcapsule transfer techniques that were previously utilized to deliver nanoparticle medicines in biomedical applications. The effective material characteristics were computed using a numerical homogenization methodology that included finite element analysis, random representative volume element, perfect contact between distinct phases, special linear boundary conditions, and the Hill–Mandel principle. To imitate the random distribution of inclusions inside a particle-filled composite, the relationship describing the inclusion’s volume fraction was adjusted by adding a regularity coefficient. Thus, a new representative volume was designed to study the effect of the non-uniform distribution of randomly sized inclusions on the effective coefficients of the composite. An analysis of the effective properties of this new composite system with metalized pores surfaces (SMPS) revealed the following features. Due to the presence of metallic impurities, the resulting electric induction field or mechanical stress field inside the piezoelectric phase is scattered, which raises the transverse piezoelectric moduli with the increase of the inclusion’s volume fraction. Also, the electrical permittivity coefficients increase steadily with the increase in the portion of the metallic impurities. According to the findings, the volume fraction of the inclusion can be considered the most critical parameter to modify the electromechanical characteristics of the SMPS. The effects of the regularity coefficient on the equivalent properties increase as the inclusion’s volume fraction increases. The effective dielectric constants decrease as the degree of regularity of the composite structure grows, increasing the effectiveness of the piezoelectric transducer in transverse energy harvesting and motor applications. The findings of the newly constructed representative volume were verified using a basic periodic unit-cell and a random representative volume based on the random sequential adsorption (RSA) method. The developed structure of the representative volume can be applied to simulate a wide range of composites in the form of solid particles. Piezoelectric transducers constructed from the proposed piezocomposite are predicted to function well in piezoelectric motors and transverse piezoelectric sensors.

A planar piezoelectric motor of two dimensional XY motions driven by one cross-shaped piezoelectric unit: A new principle.

We present a two-degree-of-freedom piezoelectric motor, which is driven by a simple cross-shaped piezo unit. Here, not only the structure of high novelty and simplicity but also the working principle is new. The cross-shaped piezo unit is sandwiched between top and bottom guiding plates with roughly equal pressing forces applied between the four free ends of the piezo unit and the plates. The working principle is as follows: A pair of opposite arms of the piezo unit quickly and simultaneously expand and contract periodically in the X direction, which results in a vanishing total friction force in the X direction; meanwhile, the other two arms in the Y direction deform slowly in a push-pull manner, which will move the aforementioned X-direction arms a step in the Y direction; then, the Y direction piezo arms restore their initial states slowly one by one. Repeating these actions will produce continuous stepping in the Y direction. Because the structure is symmetric in X and Y directions, we can similarly produce stepping in the X direction. The advantages are obvious: compact, rigid, and planar, which are all important for high stability and, hence, crucial in building an atomically resolved scanning probe microscope.

Resonant-type rotating piezoelectric motor with inchworm-inertia composite impact.

A resonant-type rotating piezoelectric motor with inchworm-inertia composite impact was designed and manufactured. It mainly comprises a stator, rotor, support shaft, and frame. The motor stator includes a clamp, driver, central connecting block, preload structure, and other auxiliary mechanisms. The clamp and driver of the motor work in a resonant state. The motor structure was optimized by using the finite element software COMSOL 5.2. Through the finite element simulation analysis, the first-order bending vibration of the clamp and the driver was selected as the working mode, and the consistency of the resonance frequency coupling was optimized and adjusted. By coordinating the bending vibration of the clamp and driver in the vertical staggered direction, the clamping foot drives the rotor to realize the unidirectional continuous rotation. The motor prototype was designed and processed, while the experimental device platform was established to verify the working principle of the motor, and the comprehensive performance of the motor was analyzed and tested. When the input driving voltage was 240VP-P, the driving frequency was 161Hz, and the preload torque of the motor was 6.9 N mm, the maximum no-load speed of the motor reached 3.23 rad/s and the maximum load torque reached 10.35 N mm. Under the same conditions, the maximum resolution of the motor rotation angle was 0.69°.

Output characteristics and experiments of a novel low frequency rotary piezoelectric motor

Output characteristics and experiments of a novel low frequency rotary piezoelectric motor

Design, development, and theoretical and experimental tests of a nonlinear energy harvester via piezoelectric arrays and motion limiters

This paper presents the design, development and test of a nonlinear piezoelectric energy harvesting array with wideband performance under directly and parametrically excited conditions; theoretical verifications of equation-type as well as finite-element-methods are also provided. The array, as the core element, consists of four cantilever beams with attached piezoelectric layers and individual tip masses; two pairs of motion limiters were designed to limit the cantilever motions. By introducing 1-pair motion limiters, a strong hardening frequency response extended the system resonance regime and generated an enhanced bandwidth; when the monotonically increased system response triggered engagement with 2-pair motion limiters, the operational bandwidth was even further extended and formed a fully merged resonance regime for energy harvesting purposes. With motion limiters, the directly excited device achieved a continuous operational frequency bandwidth from 5.7 Hz to 12.3 Hz, which is a frequency bandwidth increase of 240%; by introducing the nonlinear frequency response in parametric resonance to the proposed device, the operational frequency bandwidth is increased by 579%. The corresponding piezoelectric voltage output of the proposed device is compared with conventional no limiter and one limiter counterparts. Theoretical investigations using an equation for the motion of the system along with a time-integration solution, as well as a finite element method using ANSYS, have been carried out to verify the results, showing good agreement. The results reveal that the proposed device has potential for dealing with different excitation levels and low frequency applications while broadening the frequency bandwidth.

A self-powered intelligent glove for real-time human-machine gesture interaction based on piezoelectric effect of T-ZnO/PVDF film

In the emerging field of human-machine interaction, intelligent gesture recognition techniques have great application prospects. The traditional use of rigid and over-sized power units has restrained the development of wearable gesture recognition systems. Here, we present a self-powered intelligent glove based on piezoelectric motion sensor arrays for real-time gesture recognition. The system can be confortably worn on human hands, and mainly consists of three parts: a flexible piezoelectric motion sensor based on T-ZnO/PVDF film (T-ZnO, tetrapod ZnO nanostructures), a signal processing module for analyzing the sensing information, and a Bluetooth unit for wireless communication. The system can work without external power, and the piezoelectric output can act as both the energy source of the system and the sensing signal. The working mechanism can be attributed to the piezoelectric effect of T-ZnO/PVDF composites and with flexion and extension of the fingers, a series of pulse signals can be generated and converted into specific corresponding codes. The sensing signal can be wirelessly transmitted to smartphones through the Bluetooth unit, and the phone can recognize the codes corresponding to sign language actions and translate them. This work can potentially promote the development of the next generation of human-machine interaction systems and expand the scope of self-powered techniques and wearable electronics.

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.

A Semisolid Micromechanical Beam Steering System Based on Micrometa-Lens Arrays.

Optical beam steerers have been widely employed for information acquisitions. Numerous beam steering schemes have been developed, and each of them can satisfy practical requirements for certain scenarios. However, there is still a lack of a comprehensive approach that is able to balance all of the critical technical parameters for wide range of applications. Here, a semisolid micromechanical beam steering system based on micrometa-lens arrays (MMLAs) is demonstrated. It is operated by manipulating the probe beam over two sets of decentered MMLAs potentially driven by high-speed piezo-electric motors. Small f-numbers, well-corrected aberration, and easy lateral reproduction of micrometa-lenses optimize the overall technical parameters. As a proof-of-concept, we implement such a device exhibiting diffraction-limited resolution within a large field of view of 30° × 30°. A three-dimensional depth sensing is also performed to demonstrate its potential in light detection and ranging applications.

Highly sensitive, flexible and wearable piezoelectric motion sensor based on PT promoted β-phase PVDF

Wearable electronic devices with biocompatibility and stability to monitor the practical human physiological states are urgently expected for some intensive disease recovery or healthy fitness improvement. In this work, a highly sensitive piezoelectric sensor with the aid of polythiophene (PT) promoting polyvinylidene Fluoride (PVDF) from α-phase to β-phase was designed. Electric-sensitivity of 4.961 V/N is obtained at the low-pressure and 0.09 N periodic pressure positively produces considerable output open circuit voltage. It is proved that PT facilitates PVDF to accumulate charge carriers at their interfaces, resulting in interface polarization and thus extremely piezoelectric sensitivity. Reliability test suggested the sensor stays stable performance after a long-term (~2.6% decline after 5000 cycles) repetitive deformation. Through the practices of our assembled wearable sensor demonstrating its powerful ability in recording human joint movement and breathing, which also shows that it is very promising in online movement monitoring of personal health.

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.

Measurement and evaluation on mechanical performances of standing-wave piezoelectric motor of V-shaped sandwich-type transducer having arc tip

A prototype of the linear standing-wave ultrasonic motors having arc tip is designed and manufactured, and the output performances and mechanical characteristics were tested and evaluated using a home-made measured simple system in this study. Results show that the flexible design of the driving foot is interesting for the performance improvement and simplification design of standing-wave ultrasonic motors. The measured system is simple and is available to evaluate the output performances (thrust and speed) and mechanical characteristics curves of linear motors. The influence trend of preload and driving voltage on output speed is opposite, while the influence trend of thrust is parabola. The peak value of applied voltage is critical for the mechanical characteristic curve of piezoelectric motor. This study also supports a basic measurement approach for service performances of linear ultrasonic motors and the tribological behaviors of motor and/or actuator devices using piezoelectric vibration.

Radiation tolerance testing of piezoelectric motors for ITER (first results)

As a part of ITER diagnostics design and development, ultrasonic and stick-slip piezoelectric motors and several types of piezoelectric ceramics were tested under severe neutron and gamma ray irradiation (∼ 1019 per cm2 at E > 0.1 MeV) in a pool-type fission reactor. The fission neutron and gamma ray spectra were corrected to comply with conditions expected under ITER divertor cassettes. Taking into account possible neutron-induced amorphization of crystal structure, four types of piezoelectric ceramics were pre-selected. To restore the electronic structure of piezoelectric ceramic damaged by gamma rays, recovery polarization (i.e. heating while applying reverse bias) was suggested. The motors and piezoceramic samples were assessed for performance before and after irradiation as well as after recovery polarization. Recovery polarization was performed at 330 °C as it is expected close to the divertor cassettes during baking. Two most promising types of piezoelectric ceramics survived multiple cycles of depolarization/polarization at both 330 °C and 200 °C as appropriate for baking ITER divertor and vacuum vessel, respectively. All the experiments and procedures are described in detail.

A simple linear driving actuator for robotic arm used in land-deep sea

The small robotic arm used for amphibious operation in land and deep sea environment is one of the research hotspots at present. Traditional motor is gradually difficult to realize the amphibious driving of small robotic arm, a piezoelectric motor, which can effectively realize linear drive in both deep sea and land environment, is proposed in this paper. The structure of the designed motor is simple with the overall size less than 60 mm × 55 mm × 5.5 mm. The operating frequencies of the designed motor on land and in underwater with different depths were obtained. Experimental tests were carried out to test the driving performance of the prototype in the land and in underwater with different pressure (water depth). The maximum driving velocity of 376 mm/s and maximum load of 2.5 N can be achieved on land, and the maximum driving velocity of 215 mm/s can be obtained in underwater with pressure as 8 MPa (depth as 800 m). This work can provide an important reference for the research on linear driver of land-deep sea underwater operation equipment.

Piezoelectric motors for nanotechnology and robotics

Piezoelectric motors for nanotechnology, microelectronics, electron microscopy, adaptive optics, mechatronics and robotics are considered. The mechanical characteristics of a simple piezoelectric motor are investigated. For a piezoelectric vibration motor the angular velocity of the rotor is determined.

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.

Lift Generation by a Miniature Piezoelectric Ultrasonic Motor-Driven Rotary-Wing for Pico Air Vehicles

Actuators are key components for further miniaturization of insect-scale microrobots. It is challenging to create a new miniature actuator suited for rotary-wing pico aerial vehicles (PAVs), which have a wing span of a few centimeters and a mass of a few grams. In this paper, we propose a miniature piezoelectric ultrasonic motor that permits high-speed rotation at a sufficient torque to achieve the flight of the simplest device comprising the proposed motor and rotor blades. The prototype motor, which employs a bending vibration mode as a principle, measures 1.6 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times1.6$ </tex-math></inline-formula> mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times2$ </tex-math></inline-formula> mm and weighs 25 mg. The experimental results show that the miniature motor rotates rotor blades having a length of 20 mm with an angular velocity of over 1800 rad/s. The thrust force generated from this system exceeds its total mass of 110 mg and successfully lifts the system. Although the flight is tethered, the set of the proposed motor and rotor blades demonstrates a takeoff that represents the possibility of rotary-wing PAVs.

Piezoceramic resistance to radiation amorphization during operation in ITER

Piezoelectric motors designed for operation in the ITER tokamak-reactor must be tested for stability under severe radiation conditions. Properties of lead zirconate-titanate that is the most common type of piezoelectric materials were analyzed from the point of view on influence of radiation. It is shown that, at the expected in ITER level of radiation, this piezoceramics has a good potential for resistance to radiation induced amorphization and depolarization. Keywords: piezoceramics, radiation tests, ITER diagnostics.

Research on High Speed Piezoelectric Motor with Eccentric Rotor Which Speed Is Equal to the Driving Frequency

Research on High Speed Piezoelectric Motor with Eccentric Rotor Which Speed Is Equal to the Driving Frequency