A Miniature Self-Moving Ultrasonic Actuator With Dual-Axis-Translational/Fast/Load-Carriable Movements Inspired by Earthworm’s Wriggling/Turtle’s Crawling Motions

This article presents a miniature self-moving ultrasonic actuator (MSMUA) with dual-axis-translational/fast/load-carriable movements. When the longitudinal–torsional (L–T) hybrid vibration is excited with the spiral-groove-shaped transducer, the MSMUA can move in the x and y axes by combining the z-axis bending (Bz)/L–T vibrations and the y-axis bending (By)/L–T vibrations, respectively, which are interestingly the imitations of earthworms’ wriggling motion and turtles’ crawling motion. First, by constructing the Krimhertz-transmission-theory-based dynamic model, the modal degeneration was performed among the L–T, By, and Bz vibrations. Then, a prototype with the sizes of 67.5 × 42 × 10 mm³ and the weight of 27.23 g was fabricated to assess MSMUA’s moving/carrying/positioning performance. When MSMUA in a tethered manner moved in the x and y axes, it yielded the maximal speeds of respectively 483 and 233 mm/s (7.15 and 5.55 times of the body length per second) and the maximal payloads of respectively 1218.5 and 711.5 g (44.7 and 26.1 times of the mechanical part’s weight). In an untethered manner, the minimal step displacements reached 112 and 128 nm in the x and y axes, respectively. Benefitting from the dual-axis-translational movement and nanometer resolution, the MSMUA is potentially applicable to the wafer inspection.