Resonant-type smooth impact drive mechanism actuator using lead-free piezoelectric material

In this study, a resonant-type smooth impact drive mechanism (R-SIDM) actuator fabricated with lead-free piezoelectric materials was investigated. There is high demand for compact high-power actuators, and ultrasonic motors are a promising way to meet these requirements because of their high power density. The R-SIDM actuator is a type of linear ultrasonic motor that is driven with a quasi-saw-shaped displacement excited by a combination of two resonant sinusoidal waves. The advantage of the R-SIDM actuator is its low heat generation compared with that of conventional SIDM actuators because of its resonant drive operation. A previously proposed R-SIDM used a transducer composed of lead zirconate titanate (PZT), which has excellent piezoelectric properties but is harmful to the environment. Therefore, in the presently proposed R-SIDM actuator, PZT was replaced by the lead-free piezoelectric ceramic (K,Na,Li)NbO3 (KNLN). The actuator was used to rotate a bearing rotor to measure the driving performance, and a driving speed of 53 mm/s with no load and a maximum thrust force of 69 mN were obtained.