Self-tuned driving of piezoelectric actuators: The case of ultrasonic motors

A number of piezoelectric devices with wide applicability in industrial and technological areas, i.e. ultrasonic motors and piezoelectric transformers, are based on piezoelectric resonators. Piezoelectric resonators are electromechanical structures for which the operation point is close to resonance. This operation point must be kept close to resonance regardless of external perturbations. This paper introduces the mechatronic design of control electronic circuits for piezoelectric resonators. The design approach has been experimentally validated on ultrasonic motors. The paper analyzes the specification of optimal driving signals, the digital electronic generation of such signals and the self-tuning characteristics of these electronic drivers based on feedback loops.