In order to understand the dynamic characteristics of an ultrasonic motor stator, we proposed a modified two- dimensional axisymmetric finite element model to analyze the three-dimensional vibrational problem of piezoelectric annular and circular plates. In this work, displacement fields are properly assumed and the electric effect is included. Following the finite element method, analyses of axisymmetric and nonaxisymmetric vibration of circular and annular plate, and also the stator of ultrasonic motors can be conducted in a convenient way. Natural frequency, location of contact point and elliptic locus of the stator are then calculated. Effects by different geometry design and selected circumferential wave number are discussed. Comparisons of some typical examples are made between the present work and those available in the literature.

This report is the result of a master thesis work where the goal was to develop acontrol system for a type of ultrasonic motor. The ultrasonic motors use ultrasonicvibrations from a piezoelectric material to produce a rotating motion. They arepowered by two sinusoidal voltages and their control signals generally are thevoltages amplitude, frequency and the phase difference between the two voltages.In this work the focus is on control using only amplitude and frequency. A feedbacksignal was provided by an encoder, giving an angular position. The behavior of themotors were investigated for various sets of control signals. From collected data alinearized static model was derived for the motor speed. This derived model wasused to create a two part control system, with an inner control loop to managethe speed of the motors using a PI controller and an outer control loop to managethe position of the motors. A simple algorithm was used for the position controland the result was a control system able to position the motors with a 0.1 degreeaccuracy. The motors show potential for greater accuracy with a position feedback,but the result in this work is limited by the encoder used in the experiments.

This study has been carried out to develop and manufacture piezoelectric ceramic materials which are utilized for ultrasonic motor (USM) applications. For this purpose, the effect of compositional modifications on the dielectric and piezoelectric properties of lead zirconate titanate (PZT) based ceramics was investigated. PZT based powders were produced using the mixed oxide method. The base composition was selected as Pb(Zr0.54Ti0.46)O3. The samples in the proximity of morphotrophic phase boundary were doped with strontium, lanthanum, lead manganese niobate (PMnN) and lead manganese antimonate (PMS) in order to improve the structural characteristics and electromechanical properties which are very important for USM applications. The dielectric constant, planar coupling coefficient, mechanical quality factor, piezoelectric strain constant and tangent loss values were evaluated in accordance with standard IRE (Institute of Radio Engineers) test procedures. The results on dielectric and piezoelectric properties showed that piezoelectric ceramics with high mechanical quality factor, high piezoelectric strain constant and low tangent loss could be produced by using the aforementioned dopants. As a result, a new piezoelectric ceramic named as 0.97[PSLZT]-0.024[PMnN]-0.006[PMS] was produced with KT= 1913, Qm= 1240, d33= 540 pC/N, tan delta= 0.89%, kp= 0.57 and Tc= 235 &deg / C. This composition is a good candidate for high power applications. The ceramic samples with the developed compositions were used to produce an ultrasonic-wave type motor and the performance of the USM was evaluated in terms of speed, torque and efficiency.

To make a camera more user friendly or let it operate without an user the camera objective needs to be able to put thecamera lens in focus. This functionality requires a motor of some sort, due to its many benefits the ultrasonic motor is apreferred choice. The motor requires a driving circuit to produce the appropriate signals and this is what this thesis is about.Themain difficulty that needs to be considered is the fact that the ultrasonic motor is highly non-linear.This paper will give a brief walk through of how the ultrasonic motor works,its pros and cons and how to control it. How thedriving circuit is designed and what role the various components fills. The regulator is implemented in C-code and runs on amicro processor while the actual signal generation is done on a CPLD. The report ends with a few suggestions of how toimprove the system should the presented solution not perform at a satisfactory level.

A novel segmented electrodes linear ultrasonic motor (USM) was developed. Using a planar vibration mode concept to achieve elliptical motion at the USM drive-tip, an attempt to decouple the components of the drive-tip trajectory was made. The proposed design allows greater control of the drive-tip trajectory without altering the excitation voltage. Finite element analyses were conducted on the proposed design to estimate the performance of the USM. The maximum thrust force and speed are estimated to be 46N and 0.5370m/s, respectively. During experimental investigation, the maximum thrust force and speed observed were 36N and 0.223m/s, respectively, at a preload of 70N. Furthermore, the smallest step achievable was 9nm with an 18μs impulse. Nevertheless, the proposed design allowed the speed of the USM to vary while keeping the thrust force relatively constant and allowed the USM to achieve high resolution without a major sacrifice of thrust force.

A novel segmented electrodes linear ultrasonic motor (USM) was developed. Using a planar vibration mode concept to achieve elliptical motion at the USM drive-tip, an attempt to decouple the components of the drive-tip trajectory was made. The proposed design allows greater control of the drive-tip trajectory without altering the excitation voltage. Finite element analyses were conducted on the proposed design to estimate the performance of the USM. The maximum thrust force and speed are estimated to be 46N and 0.5370m/s, respectively. During experimental investigation, the maximum thrust force and speed observed were 36N and 0.223m/s, respectively, at a preload of 70N. Furthermore, the smallest step achievable was 9nm with an 18μs impulse. Nevertheless, the proposed design allowed the speed of the USM to vary while keeping the thrust force relatively constant and allowed the USM to achieve high resolution without a major sacrifice of thrust force.

This thesis deals with the design, fabrication and analysis of a novel actuator for a fish-like swimming mini robot. The developed actuator is tested on a mini boat. The actuator relies on a novel piezoelectric ultrasonic motor, developed according to the design requirements of actuator for fish-like swimming mini robots. Developed motor is within the dimensions of 25x6x6 mm in a simple mechanical structure with simple driving circuitry compared to its predecessor. Bidirectional rotation of the motor is transformed to a flapping tail motion for underwater locomotion in a simple mechatronic structure. The simplicity in the motor and actuator enables further development on the miniaturization, improvement on the performances as well as easy and low cost manufacturing. The developed actuator is a candidate to be used in mini swimming robot with fish- like locomotion.

Η εργασία αυτή εχεις ως αντικείμενο την μελέτη και την κατασκευή ενός μετατροπέα συντονισμού για την οδήγηση ενός πιεζοηλεκτρικού κινητήρα οδεύοντος κύματος τύπου Ultrasonic. Αρχικά γίνεται μια θεωρητική αναφορά στους πιεζοηλεκτικούς κινητήρες και τους ηλεκτρονικούς μετατροπείς ισχύος ενώ ακολουθεί η προσομοίωση του μετατροπέα στο Pspice. Ακολούθως αναλύεται η διαδικασία της κατασκευής και ακολουθούν τα πειραματικά αποτελέσματα καθώς και τα συμπεράσματα που λάβαμε. / In this thesis someone can find about designing and manufacturing a resonant inverter in order to control a piezoelectric traveling wave ultrasonic motor. In the first chapters someone can read about the piezoelectric phenomenon, piezoelectric motors and about electronic converters which control the velocity of motors. Next there is a presentation of the Pspice simulation model and results. Furthermore there is the manufacturing procedure of the inverter and at the end there are the results and conclusion of the thesis.

A qualitative analysis of a rotary traveling wave-type ultrasonic motor (USM) used to supply feedback forces in force-feel systems is carried out. Prior to simulation, the subsystems and contact mechanics needed to define the motor's equations of motion are discussed along with the pitfalls of modeling a USM. A mathematical model is assembled and simulated in MATLAB Simulink. Accompanying the dynamic model, a new reduced model is presented from which predictions of USM performance can be made without a complicated dynamic model. Outputs from the reduced model are compared with those of the dynamic model to show the differences in the transient solution, agreement in the steady state solution, and above all that it is an efficient tool for approximating a motor's steady state response as a function of varying the motor parameters. In addition, the reduced model provides the means of exploring the USMs response to additive loading, loads acting in the direction of motor motion, where only resistive loads, those opposite to the motor rotation, had been considered previously. Fundamental differences between force-feel systems comprising standard DC brushless motors as the feedback actuators and the proposed system using the USM are explained by referencing the USM contact mechanics. Outputs from USM model simulations are explored, and methods by which the motor can be implemented in the force-feel system are derived and proven through simulation. The results show that USMs, while capable of providing feedback forces in feel systems, are far from ideal for the task. The speed and position of the motor can be controlled through varying stator excitation parameters, but the transient motor output torque cannot; it is solely a function of the motor load, whether additive or resistive. / Master of Science

The traveling wave ultrasonic motor is considered for use in haptic devices where a certain input-output relation is desired between the applied force and the resulting motion. Historically, DC motors have been the standard choice for this purpose. Owing to its unique characteristics, the ultrasonic motors have been considered an attractive alternative. However, there are some limitations when using the ultrasonic motor for force-feedback applications. In particular, direct torque control is difficult, and the motor can only supply torque in the direction of motion. To accommodate these limitations we developed an indirect control approach. The experimental results demonstrate that the model reference control method was able to approximate a second order spring-damper system.