A standing wave ultrasonic stepping motor using open-loop control system

We propose a standing wave ultrasonic stepping motor with blades and grooves for positioning. The step-by-step movements are achieved by applying the square wave driving voltage and the high-voltage pulse in turn. The prototype with a diameter of 30 mm, a height of 10 mm is experimentally characterized. The motor is superior to those previously reported due to the positioning mechanism for eliminating displacement cumulative error when using an open-loop control system. Also, the operating mode and the metal-to-metal friction drive ensure a stall torque of 0.055 Nm under a relatively low operating voltage of 100 Vpp at a resonance frequency of 74 kHz.