A modal sensor integrated circular cylindrical wedge wave ultrasonic motor

Tai Ho Yu, Ching-Chung Yin*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


This study investigates a new circular cylindrical wedge wave ultrasonic motor (WW-USM) integrated with modal sensors. The presented motor is driven by continuous wedge waves of the fundamental modes with an integer circumferential number. In this design, the constructive interference of two equal-intensity standing waves actuated by two comb transducers generates a traveling wedge wave. Dual-phase electrodes were parallel to the axis placed on a piezoelectric (PZT) tube at a distance of 1/4 wavelength. Two orthogonal sinusoidal signals at the resonant frequency of designated flexural mode exerting on the electrodes have the WW-USM operate in bidirectional rotation. The base height of the stator was appropriately tuned to achieve an excellent modal separation from other vibration modes. A modal sensor on the border of the PZT tube was designed to detect the dynamic characteristics of the WW-USM and to improve the performance. The wedge wave motor has a flexible mechanical performance between the angular speed and output torque. Varying the contact position of the rotor on the inclined surface of the stator may exchange the angular speed for torque output. No further modification of the entire motor structure is needed. The prototype WW-USM driven by the flexural mode F(1, 4) under 1 N static preload was operated by an AC voltage of 400 V pp at the frequency of 36.605 kHz. The maximum values of angular speed, output torque, and electromechanical transduction efficiency are 225 rpm, 15.736 mN m, and 16.22%, respectively.

Original languageEnglish
Pages (from-to)144-154
Number of pages11
JournalSensors and Actuators, A: Physical
Issue number1
StatePublished - 1 Feb 2012


  • Modal separation
  • Ultrasonic motor (USM), Modal sensor
  • Wedge wave

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