Computer-Aided Design and Optimization of Piezoelectric Ultrasonic Motors

Piezoelectric ultrasonic motors are superior to electromagnetic micro motors, because their efficiency remains theoretically constant during miniaturization. However, the still relatively recent technology has a considerable unexploited optimization potential. Numerical structural analysis by the means of the finite element method (FEM) is a common approach for dimensioning piezoelectric motors. Consequently, there is a need for efficient optimization procedures fitted to the FEM simulation. We developed a dedicated design methodology to first well understand the influence of the geometrical parameters on the movement of the motor. The parameters with the strongest influence on the objective function, the vibration amplitude of the resonator, are used in a following optimization stage. Functional models of rotary and linear motors are built in order to demonstrate their operation. Interferometric measurements validate quantitatively the FEM model along with the suggested design methodology.