Structural Control of Nonlinear Dynamical Behaviour of Non-Contact Standing Wave Ultrasonic Motor

Abstract

The article describes the design and control of dynamical behaviour of a non-contact ultrasonic motor with flexurally-vibrating ring-shaped stator and rotor provided with blades. Due to asymmetric arrangement of blades (structural asymmetry), rotational movement of the rotor can be produced by excitation of standing waves in the stator in contrast to other non-contact ultrasonic motors relying on application of travelling waves. This simplifies design and control of the motor. Dynamics of the rotor is studied using a finite element method and qualitative theory of nonlinear conservative systems. It is shown that the control of structural asymmetry (particularly, application of an asymmetric rotor with twinned design) can be used for creation of a dynamical system with no equilibrium points. In such a system it will be possible to set rotor into stable rotational motion for any initial angular position.