Elliptical Displacements Research Articles

Design of an ambulatory piezoelectric actuator which has T-shape stator

T-shaped ambulatory piezoelectric actuator which can be used for various purposes such as lifesaving and environmental monitoring was proposed. The actuator consists of eight piezoelectric benders, t-shaped stator, and four legs, and it is very simple in structure and has the advantages of being easily manufactured and downsizing. It is also driven by four legs and can be moved forward and backward. The piezoelectric bender was composed of a carbon body and a ceramic plate. Vibration motions of the piezoelectric benders in x and z axes were transfer to the legs and the elliptical displacements at the ends of the legs were obtained by combination of the phase difference of 90 degrees. Characteristics of the actuators were simulated by finite element analysis, and the optimized prototype actuator was fabricated and experimented.

Driving characteristics of a hexadecagon-shaped ultrasonic motor

A novel hexadecagon-shaped ultrasonic motor is proposed. The stator is easy to fabricate because of its simple structure. The stator of the hexadecagon ultrasonic motor is composed of an elastic ring and ceramics. The elastic ring has sixteen sides and angles. The eight ceramics are attached on the outer surfaces of the eight sides of the ring. When rotor of the cylindrical shaft is inserted inside the ring stator, the central lines of the sixteen sides of the stator hold the shaft with slight pressures. This slight pressure is the preload of the motor and it can be controlled by the radius and the thickness of the ring. When two AC voltages that have a 90-degree phase difference are applied to the eight ceramics, elliptical displacements of the inner surface of the ring are obtained. These elliptical displacements of the inner surface rotate the shaft rotor through friction. The proposed hexadecagon ultrasonic motor was designed and analyzed by using a finite element analysis (ATILA), depending on the number of piezoelectric ceramics and hexadecagon modes. As a result, the stator was optimally designed by defining the output displacement characteristics, which depend on changes in the chosen parameters.

Driving characteristics of an ultrasonic rotary motor consisting of four line contact type stators

A new type of ultrasonic rotary motor that can replace existing ultrasonic motors for driving camera zoom lenses was proposed and investigated experimentally. The proposed motor composed of four roof-shaped stators. On the upper surfaces of each roof-shaped stator, two rectangular ceramics were attached. When two AC voltages with a 90° phase difference were applied to the ceramics, elliptical displacements occurred at the tip line of the actuator. By combining these elliptical displacements of the four stators, rotational motion of the stator could be achieved. If a circular disk rotor was positioned on the stator, vibrations of the stator were transferred through the four contact lines between the stator and the rotor. Preload of the motor could be controlled by the jointing bolt, which went through the center of the disk rotor and the ball bearings. The finite element analysis (FEA) simulation program ANSYS was used to analyze the elliptical displacement characteristics in relation to changes in the size of the elastic body, piezoelectric ceramics, friction tips, frequency, and applied voltages. A prototype motor was fabricated, and its driving characteristics such as impedances, vibration amplitudes, rotational speed, and torque were measured.

Speed and Torque Characteristics of Three-Phase Ultrasonic Motor

A three-phase ultrasonic motor was proposed as an actuator for small precision machinery. Twelve ceramic plates were attached on upper and bottom sides of the metal plate. When three-phase alternating voltage was applied to the stator, elliptical displacements were generated at the three inner edges of the stator. The displacement characteristics and resonance frequency were obtained by using a finite element analysis program. The maximum displacement was occurred at frequency of minimum impedance. The effectiveness of the proposed design was verified experimentally. By measuring characteristics of the motor such as speed and torque. When pre-load to rotor was increased, motor speed was decreased and torque of the motor was increased. Three contact points between the rotor and stator made stable driving of the motor.

탄성체 재질 변화에 따른 16각형 초음파모터의 토크 특성 연구

In this study, novel ultrasonic rotary motor of hexadecagon shape stator was proposed. Stator of the hexadecagon ultrasonic motor was composed of an elastic ring and ceramics. The elastic ring had sixteen sides and sixteen angular points. Eight ceramics were attached on the outer surface of the eight sides of the ring. When rotor of cylindrical shaft was inserted inside of the ring stator, central lines of the sixteen sides of the stator hold the shaft by the slight pressures(frictions). This slight pressure was a preload of the motor and it could be controlled by radius and thickness of the ring. When two sinusoidal voltages which have 90 degree phase difference were applied to each four ceramics, elliptical displacements of inner surface of the ring were obtained. These elliptical displacements of the inner surface rotated the shaft rotor through the frictions. The proposed hexadecagon ultrasonic motor was designed and analyzed by using the finite element method (FEM), depending on materials of the elastic ring. Based on the FEM results, one model of motor which showed maximum displacement at contact points was chosen and fabricated. And characteristics of the motor were compared with simulated results. When the motor was fabricated with these results, EL20ET0.5CT0.5CW2 model showed 115[rpm] speed about input voltage of 60[Vrms] at 65.6[kHz]. And the maximum torque of 6[gfcm] was obtained. From these results, the hexadecagon shaped ultrasonic motor can be used to actuator for optical device which needs detailed position control. Also it can be used to medical and portable device by reducing size and weight.

Design and fabrication of a hollow tray shaped ultrasonic motor

A hollow tray shaped ultrasonic motor was developed and analyzed. The shape of conventional rectangular frame ultrasonic motor was changed to have a stable line contacts between the stator and the corn-shaped rotor. Stator of the motor consists of the hollow tray-shape elastic body and four rectangular-plate ceramics. Four ceramics were attached to outer surfaces of the square elastic body. The other advantages of this motor are that pre-load can be imposed by the weight of the rotor. As shown in Fig. 1, when two AC voltages which have 90° phase difference were applied to the four ceramics, elliptical displacements of inner surfaces of the stator were obtained. To find maximum displacement model that generates elliptical displacement at the center lines of the inner surfaces, vibration patterns and elliptical displacements were analyzed by using the finite element analysis program ATILA. Prototype of the motor was fabricated and speed and torque characteristics were measured and analyzed.

Design and Fabrication of Three Touch Point Thin Ultrasonic Rotary Motor

A novel structure three touch points thin ultrasonic rotary motor has been proposed to enable the actuator to use in small mobile equipment. A thin stator of simple structure is advantageous to use in tight spaces. Also, three points of contact enables to stable driving. Twelve ceramics plates were attached on upper and bottom side of the metal plate. When three phase alternating current sources are applied to the stator, elliptical displacements are generated at three inner edges of the stator. Modeling of the ultrasonic motor was done and the displacement characteristics were defined by using finite element analysis program. The effectiveness of the proposed design was verified by experiments. Characteristics of the motor such as speed, and input voltage were measured by using the driver and measurement equipment. Maximum displacement was appeared at frequency of minimum impedance. The resonance frequency was inversely proportional to the ceramic length. The maximum speed of 220 [rpm] was obtained at the resonance frequency, 76.4 [kHz]. The speed increase somewhat linearly with increasing applied voltage.

Design and Fabrication of Hexadecagon Type Ultrasonic Motor

Ultrasonic rotary motor which has hexadecagon shape stator was proposed. Stator of the hexadecagon ultrasonic motor was composed of an elastic ring and ceramics. The elastic ring had sixteen sides and sixteen angular points. Eight ceramics were attached on the outer surface of the eight sides of the ring. When two sinusoidal voltages which have 90 degree phase difference were applied to each four ceramics, elliptical displacements of inner surface of the ring were obtained. These elliptical displacements of the inner surface rotated the shaft rotor through the frictions. The proposed hexadecagon ultrasonic motor was designed and analyzed by using the finite element method (FEM). Based on the FEM results, the rotational speed of the fabricated motor was measured by changing the driving frequency and voltage. As FEM results, large displacements at contact points of the stator could be obtained from thinner elastic ring and also thinner ceramics. Rotational speed of 61 [rpm] was obtained from the fabricated motor by applying 10 [V] of alternating voltages.

Motional characteristics of ultrasonic motor using Λ (lambda)-shaped stator

Abstract In this study, characteristics of novel ultrasonic motor with lambda shaped stator were investigated. A thin metal plate was used as a Λ(lambda)-shaped stator and four ceramic plate were attached on upper and bottom surface of the metal plate. From the stator, elliptical displacements of the contact line were obtained. When two sinusoidal sources with phase difference of 90° were applied to the ceramics, the symmetric and anti-symmetric displacements were combined at the contact line of the stator to make the elliptical motion. A finite element analysis (ATILA) was used for simulating the motional pattern of contact line of the stator. Stator characteristics depending on changes of ceramic size and thickness of metal were analyzed. The motor was fabricated by using results of FEA. Characteristics of the motor such as frequency, speed, torque, and pre-load were measured by using the driving system and measurement equipment.

Driving characteristics of a thin square frame-type ultrasonic motor

A thin, square, frame-type ultrasonic motor was proposed for applications in small actuators. The stator is easy to fabricate because of the simple structure where eight piezoelectric ceramics are attached on the thin square frame-shaped elastic body. When two sinusoidal sources with a phase difference of 90 degrees are applied to the stator, elliptical displacements are generated at the four edges of the stator. The designed rotor is revolved by the displacements. A finite element method was used to simulate the generated displacements, and a driving experiment was then conducted to compare the output characteristics with the results of the simulation.

Driving Characteristics of a Simple Square-Frame Ultrasonic Motor

A novel design of a simple square-frame USM (ultrasonic motor) was proposed. The stator of the motor consists of a square-frame shape elastic body and four rectangular plate ceramics. The four ceramics were attached to outer surfaces of the square-frame elastic body. The same phase voltages were applied to the ceramics on horizontal surfaces, and 90 degree phase difference voltages were applied to the ceramics on vertical surfaces. When the four outer edges of stator were clamped, the bending vibrations of the right angled bars were transformed into travelling vibrations and elliptical displacements were generated at the center of the bars. To find an optimal size of a stator, that generates elliptical displacement at the centers of the inner surfaces, the finite element analysis program ATILA was used. The analyzed results were compared to the experimental results. As result, the model EL10W3T0.5_CL7 which generates the maximum elliptical displacement was chosen by analyzing the resonance mode according to changes in frequency.

Driving Characteristics of the Thin-Type Ultrasonic Motor Using Microcontroller

This paper represented driving characteristic of a thin-type ultrasonic motor by fabricating and utilizing two kinds of drivers which could generate sinusoidal wave, square wave, respectively. A thin brass plate was used as a cross shaped vibrator and sixteen ceramic plates were attached on upper and bottom side of the brass plate. From the thin stator, elliptical displacements of the four contact tips were obtained. When two harmonic voltages which have 90° phase difference were applied to the ceramics, the symmetric and anti-symmetric displacements were generated at inside of the tips to make the elliptical motion. A finite element analysis (ATILA) was used for simulating the motional pattern of contact tips of the stator. The characteristics of the motor such as speed, torque, and current consumption were measured by applying sinusoidal waves through driving equipment which composed of function generator and power amplifier. As a result, the speed and the torque changed linearly at both driving frequency of 88.6 ∼ 87.6[kHz] and voltage of 24∼36[V]. Two-drivers which generate sinusoidal waves and square waves were designed and compared through some experiments in order to be put to practical use. In conclusion, the drivers had similar characteristic of speed-torque at alike frequency and voltage range. The square wave driver was recommended to control the motor linearly among two drivers by reason of practical use and simplification of driver.

Thin-Type 초음파모터의 설계 및 제작

In this paper, the characteristics of a thin-type ultrasonic motor generating elliptical displacements analyzed by FEM are presented, and then fabrication of the motor is then described. The structure of the motor consists of sixteen ceramic pieces attached to the upper and bottom surfaces of an elastic body. The principle of the motor is to apply alternating voltages which have a 90 phase difference to the attached ceramics, and then elliptical displacements are generated at four edges of the elastic body. Then the rotor is moved by the elliptical displacements. In the case of a ceramic thickness of 1.5, the highest speed was obtained at 79 kHz. In the case of a ceramic thickness of 2 mm, the highest speed was obtained at 77.5 kHz. Consequently, the speed and torque of the ultrasonic motor (USM) increased linearly with increasing applied voltage.

Design of thin cross type ultrasonic motor

This paper proposes a newly designed structure for a thin ultrasonic rotary motor. A thin brass plate is used as a cross-shaped vibrator and sixteen ceramic plates are attached to the top and bottom sides of the brass plate. To find the optimum size for the prototype motor, the stator motions were simulated using ATILA by changing the length and thickness of the ceramics. In the results, the stators commonly had three resonance peaks on the admittance curve; the contact tips of the stator moved at trajectories tangential or normal to these resonance peaks. Elliptical displacements of the tips were obtained at off-resonance frequencies. The maximum displacements at the resonance peaks were compared and the maximum displacements of the contact tips were obtained at a length, width, and thickness of 18, 3, and 1.8 mm respectively. With the fabricated prototype motor, high rotational speeds were obtained by applying relatively low voltages. Speed and torque were increased linearly by increasing the voltage. However, torque decreased when the input voltage went over 24 V.

박형 초음파모터의 최적 설계

In this study, novel structured thin ultrasonic rotary motor has been proposed. Ultrasonic motors are based on an elliptical motion on the surface of elastic body. Thin brass plate was used as a cross shaped vibrator and eight ceramic plates were attached on upper side and bottom side of the brass plate. From the thin stator, elliptical displacements of the four contact tips were obtained. To find the optimal size of the stator, motions of the motors were simulated using ATILA by changing length, width and thickness of the ceramics. The stators had commonly three resonance peaks and contact tips of the stator moved on tangential or normal trajectories at these resonance peaks. The maximum displacements at the resonance peaks were compared. As results, maximum displacements of the contact tips were obtained at the length of 16 mm, width of 6 mm and thickness of 0.4 mm. Changes of the resonance frequencies were inversely proportional to the length of ceramic and proportional to the width of ceramic. The motor was fabricated by using the designed stator. And, the characteristics of the motor were compared with the simulated results. When the motor was fabricated with these results, speed fo 935 rpm was obtained by input voltage of 25 Vrms at 93.5 kHz.

The directional radiation of long waves from bottom deformations of finite duration

The process of generation of two-dimensional (2D) wave motions during small elliptical displacements of the bottom which occur for a finite time interval is considered within the framework of the linear theory of long waves in a basin of constant depth. The spatial structure and the amplitudinal and energy characteristics of the emerging directional surface wave are analysed for bottom deformations of a special form.