Parametric design of PI controllers for piezoelectric ultrasonic transducers

Piezoelectric ultrasonic transducers are widely used and can offer great benefits, e.g., in ultrasonic machining, cleaning, and cutting. However, due to the resonance behavior of these transducers, feedback controllers that track the resonance frequency and regulate the vibration amplitude are often indispensable to ensure efficiency. This article presents a generic and efficient approach to designing proportional-integral controllers for piezoelectric ultrasonic transducers using the method of pole-zero cancellation based on a model of their vibration amplitude and phase dynamics. The parametric design method was experimentally applied to a piezoelectric ultrasonic periodontal scaler and compared with other tuning methods to demonstrate its advantages. The parametric design methodrequired ten times fewer experiments to parameterize the controller than the Ziegler-Nichols method, for instance, and resulted in a closed-loop system with better load rejection than the other tuning methods. The results document that the new method can considerably simplify and accelerate the development of performant feedback controllers for piezoelectric ultrasonic transducers.