Ultrasonic motors with polymer-based vibrators

Abstract

With their characteristics of low density and elastic moduli, polymers are promising materials for making ultrasonic motors (USMs) with high energy density. Although it has been believed for a long time that polymers are too lossy to be applied to high-amplitude vibrators, there are several new polymers that exhibit excellent vibration characteristics. First, we measure the damping coefficients of some functional polymers to explore the applicability of polymers as vibrators for USMs. Second, to investigate the vibration characteristics, we fabricate bimorph vibrators using several kinds of polymers that have low attenuation. Third, a bending mode USM is fabricated with a polymer rod and four piezoelectric plates bonded on the rod as a typical example of a USM. Through an experimental investigation of the motor performance, it was found that the polymer-based USMs exhibited higher rotation velocity than the aluminum-based USM under a light preload, although the maximum torque of the polymer-based USMs was smaller than the aluminum-based USM. Among the tested polymers, polyphenylenesulfide was a prospective material for USMs under light preloads because of the high amplitude and lightweight of polyphenylenesulfide.

Pellicular Morphing Surfaces for Soft Robots

“…However, the small forces produced make them less appealing at the scale required. Ultrasonic motors have been fabricated by bonding polymers to piezoelectric materials [16] and could drive motion between the strips. Another approach could be to generate movement through the use of travelling waves, such as through soft, active materials like dielectric elastomers [17].…”

A Traveling-Wave Linear Ultrasonic Motor Driven by Two Torsional Vibrations: Design, Fabrication, and Performance Evaluation

“…Kondo et al [22] bonded two groups of lead-zirconate-titanate (PZT) elements onto two ends of a rectangular bar and generated a traveling wave (TW) on the middle part to drive the slider. In general, lightweight is achievable with B 2 motors [1,10,23,24], but their mechanical outputs are limited as electromechanical coupling of bending vibration is not strong [25,26]. Second, several motors utilize L 2 modes as longitudinal vibration generally exhibits high electromechanical coupling [1,3].…”

A Dumbbell Shaped Piezoelectric Motor Driven by the First-Order Torsional and the First-Order Flexural Vibrations

“…Recently, piezoelectric motors have become increasingly in demand in optical instruments, automatic stages, and robotics' arm joints [1,7,12,15]. Vibrators are core components for piezoelectric motors, and they are generally composed by lead-zirconate-titanate (PZT) ceramics and metal vibrating bodies [1,[16][17][18][19]. PZT ceramics basically work in three modes-i.e., thickness (d 33 ), extensional (d 31 ), and shear (d 15 ) modes [1,20], where the d 33 and d 31 modes have been commonly adopted in conventional piezoelectric motors.…”