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This dissertation, Control of Travelling-wave Ultrasonic Motors by Sheung-wai, Chung, 鍾尚威, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled Control of Travelling-wave Ultrasonic Motors submitted by CHUNG, Sheung Wai for the degree of Doctor of Philosophy at the University of Hong Kong in April 2006 A traveling-wave ultrasonic motor (TUSM) converts electricity into mechanical motion using piezoelectric effect. Generally two AC sinusoidal voltages with finite phase difference are employed to produce a continuous, time-varying bending of the stator. Such bending forms a traveling-wave along the surface of the stator. Since the rotor is hard pressed to the stator by a pressure disc, it is driven into rotation. The TUSM features a high holding torque. It offers a high torque at low speed characteristics. Its response is fast and it is much more than the traditional DC servomotor. Since it utilizes piezoelectric effect, there is no electromagnetic interference. Although the TUSM is very suitable for many mechatronic applications, its speed exhibits nonlinear response to controllable inputs. Such peculiarity presents a significant challenge for servo control using the TUSM. Different approaches of modeling have been adopted. These include equivalent circuit analysis, analytic approaches and finite element analysis. Unfortunately, they are either too complex or computationally intensive for controller design and simulation. In consequence, various empirical controllers have been employed. The first objective of this project is to develop a practical model of TUSM for control purposes. It relates the controllable inputs to the output torque of the TUSM. The second objective is to utilize this model to develop various modes of torque control, thus demonstrating its effectiveness. Both passive compliance and active speed controls are developed. Passive compliance control includes both the self-locking torque control and the reacting torque control. Neurofuzzy control and a practical model-based control have been explored for active speed control. Hence, all the control strategies which are essential for a robot manipulator are available, allowing TUSM to be deployed to it. A digital signal processing (DSP) based control system has been developed for experimental purpose. It consists of a DSP microcontroller, a power electronic drive, a TUSM and an optical encoder. The microcontroller provides two trains of PWM signals with variable frequency and duty ratio to the drive. The frequency expands the controllable speed span and the duty ratio offers a partial linear relationship to the motor torque. Through resonance, the drive converts a dc voltage into two sinusoidal voltages with finite phase difference. They are required to drive the TUSM. The optical encoder provides speed feedback to the microcontroller. This DSP-based system can therefore readily be deployed for standalone embedded mechatronic system. Experiments have demonstrated the effectiveness of self-locking torque and reacting torque control. Superior performance in tracking and disturbance rejection is also observed in both neurofuzzy and practical model-based controls. An abstract of exactly 419 words Signed ________________ Chung Sheung Wai DOI: 10.5353/th_b3689003 Subjects: Ultrasonic motorsServomechanisms

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