A piezomotor for the small actuator market

Because of their intrinsic qualities (high power density, silent working...), piezomotors will eventually replace electromagnetic motors in the small actuators market (mechanical power of few watts). But at present time, the industrialisation cost of this kind of motor is still standing in the way of an important industrial development. This paper describes design and experimental phases of an ultrasonic motor development. The reduction of production cost and the reliability of manufacture process have always been preference shares while preserving workable mechanical characteristics. By so doing, a 20 mm-diameter motor delivering a mechanical output in the 1 watt range could be produced with a cost price lower than 15 $ (excluding power supply and control). Using PZT rods "arranged in 3/4 of wavelength" to generate the travelling wave, this motor makes full use of conical couplers to reduce mechanical losses and optimise mechanical performances.