A non-contact linear bearing and actuator via ultrasonic levitation

In this study, the design and testing of a linear bearing using near-field acoustic levitation (NFAL) phenomenon was performed. A pair of Langevin transducers placed at either end of a beam with either a right-angle V-shaped or A-shaped cross-section was used to excite and absorb ultrasonic flexural vibrations transmitted along the length of the beam from one transducer to the other. The beam was used as a guide rail, supporting a slider formed from a short length of beam with the same cross-section. This arrangement provides a small and inexpensive non-contact bearing with magnetic field immunity and without generating a magnetic field, both useful characteristics for clean room and precision actuators. The slider was levitated by the vibration of the beam tip to 100 mu m, and was moved successfully in either direction by traveling waves transmitted along the guide rail. In a 300-mm long prototype, objects up to 160 g (60.5 k g/m(2)) were levitated and transported. A transportation speed of 138 mm/s was obtained for a slider of 90 g. The stiffness of the levitation was found to be 1. 1 N/mu m/m(2) for this prototype. (c) 2006 Elsevier B.V. All rights reserved.