Speed control of traveling-wave ultrasonic motors using a practical modeling approach

This article presents a new approach for speed control of traveling-wave ultrasonic motors. The key is to provide a practical model to allow for controller design and simulation using standard simulation software. The model offers a simple relationship between the control inputs and the output torque. Operating frequency and voltage amplitudes are used as control inputs through direct pulse-width-modulation. A speed control system using a low cost DSP microcontroller has been implemented. A PI controller has been designed through simulation to compare with the experiments. Consistent results have been obtained, demonstrating the feasibility, and effectiveness of this approach.