Investigation into vibration filtering for reducing friction loss of ultrasonic motors through a numerical approach

Ultrasonic motors (UMs) have emerged as a leading solution for actuators in biomedical equipment, aerospace applications, and other fields, owing to their distinct advantages, such as compact structures and self-locking ability. The operating principle of nearly all UMs heavily relies on friction coupling. Excluding material fatigue, friction loss is the primary factor affecting the UMs' service life. To address this challenge, we propose, for the first time, the integration of vibration filtering into UMs to minimize friction loss during operation. The core innovation of this study involves partitioning the mover into two components: the primary mover and the secondary mover, connected by a flexible mechanism. The lightweight secondary mover remains in contact with the vibrator, while the primary mover contains the majority of the mover's mass. The flexible mechanism serves as a filter, effectively preventing the transmission of harmonic vibrations, which are known to contribute to friction loss, from the secondary mover to the primary mover. By developing a generalized kinematic model for UMs, we systematically examined the feasibility of our approach with different parameters. Our findings demonstrate that, under a preload of 100 N, friction loss can be reduced by approximately 5 times. Although this technique introduces additional structural complexity, we contend that it holds heuristic significance for enhancing the efficiency of UMs, despite still being at the proof-of-concept level.