Miniaturization of the traveling wave ultrasonic linear motor using series connection of bimorph transducers

Small-sized ultrasonic linear motors are demanded for replacing pneumatic actuators. We propose the structure of traveling wave ultrasonic linear motor less than 10 mm in diameter using series connection of bimorph transducers. The length of one bimorph transducer is determined to be 25 mm being based on finite element analysis for the resonance frequency of 66 kHz. A traveling wave of bending vibration is excited along the transmission bar with the superposition of two waves which have phase difference of ±90 degrees for each. The maximum thrust of 0.5 N was obtained.