Adaptive resonant frequency tracking of piezoelectric transducers based on variable universe fuzzy PI control

As the power core of ultrasonic instruments, the piezoelectric transducer generates a strong impact force when operating at resonance. However, the influence of various uncertainly applied payloads on the electrical characteristics of piezoelectric transducers poses a challenge in the context of achieving stable control of the resonant state. To address this issue, this paper proposes a novel resonant frequency tracking control method based on a variable universe fuzzy proportional–integral (PI) control strategy. Experimental results demonstrate that the variable universe adjustment mechanism provides the controller with an enhanced system response speed while maintaining high control accuracy. The variable universe fuzzy PI controller exhibits a maximum settling time of 0.78 s and an overshoot of 16.2°, which represent reductions of 51.3% and 59.4%, respectively, compared with a conventional fuzzy PI controller. The proposed control strategy can realize high-precision and consistent resonant frequency tracking for piezoelectric transducers under dramatically varying impedance conditions induced by uncertainly applied loads, providing valuable insights for the driving and control of these transducers.