Optimization of a single phase ultrasonic linear motor

Piezoelectric ultrasonic motors are superior to electromagnetic micromotors, 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 developped 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, were used in a following optimization stage. The operation of the optimized motor was proofed on a test bench. Interferometrical measurements validated quantitatively the FEM model along with the suggested design methodology.