Title page for ETD etd-09092008-101507


Type of Document Master's Thesis
Author Murphy, Devon Patrick
Author's Email Address demurphy@vt.edu
URN etd-09092008-101507
Title Analysis of a Rotary Ultrasonic Motor for Application in Force-Feel Systems
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Inman, Daniel J. Committee Chair
Kasarda, Mary E. F. Committee Member
Seigler, Thomas Michael Committee Member
Keywords
  • Additive Loading
  • Resistive Loading
  • USM
  • Ultrasonic Motor
  • Haptic
  • Torque Control
  • Control Stick
  • Force Feedback
Date of Defense 2008-08-25
Availability unrestricted
Abstract
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.
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