A Novel Dual-Rotor Ultrasonic Motor Applied for Underwater Propulsion

In this paper, a novel dual-rotor ultrasonic motor applied for underwater propulsion is proposed. It is briefly composed of rotor unit, stator unit, prepressure regulating mechanism, gear unit and bracket. The rotor unit comprises two rotating shafts, two driving disks and a pair of propellers with opposite turning directions. The stator unit comprises a metal matrix and a circular piezoelectric ceramic wafer. The metal matrix is in the shape of a spindle with its two ends serving as driving feet. The upper edge of the driving feet is used for generating propulsion force via contact friction induced by the first longitudinal vibration of the stator. The prepressure regulating mechanism is a torsion spring which can adjust the amount of deformation. It can be seen from experimental results that the speed of the prototype motor can reach 110 r/min and the stalling torque can reach 3 mN·m when the driving frequency is 63.55 kHz and the driving voltage is 150 V
_p-p
. The design and measurement results provide useful guidance for the application of ultrasonic motor in underwater environment.