Fig. 1. Vibration model of PEM

Fig. 2. Structure diagram of FaaPEM

Fig. 3. Dynamic heat exchange model of PEM

Fig. 4. FaaPEM stabilization control system

Fig. 5. System diagram

Fig. 6. Sweep result diagram. (a) First piezoelectric actuator; (b) second piezoelectric actuator

Fig. 7. Amplitude of the phase delay varies with the driving voltage. (a) First piezoelectric actuator voltage regulation diagram; (b) second piezoelectric actuator voltage regulation diagram

Fig. 8. Phase difference scanning results

Fig. 9. Half wave state. (a) Driven by single piezoelectric actuator; (b) driven by dual piezoelectric actuators; (c) FaaPEM phase delay as a function of time; (d) curve of phase delay of FaaPEM without feedback as a function of time

Fig. 10. Quarter wave state. (a) Driven by single piezoelectric actuator; (b) driven by dual piezoelectric actuators; (c) FaaPEM phase delay as a function of time