Novel Design and Control of Ultrasonic Transducers for a Media-Free Contactless Micro-Positioning System

Microelectromechanical systems (MEMS) are increasingly used for both industrial and consumer applications. To improve the accuracy and efficiency of MEMS fabrication and to overcome the limitations of conventional contactless positioning systems, this study introduces a novel positioning concept that combines ultrasonic levitation with electromagnetic actuation. Squeeze-film effects generated by high-frequency ultrasonic transducers enable levitation, while fast-response reluctance forces from electromagnets govern the positioning dynamics without requiring bulky mounting frames. A novel double-acting ultrasonic transducer with a Gaussian-profile horn is proposed, ensuring approximately uniform vibration distribution and increased levitation force. The double-acting design enables levitation on both surfaces, simplifying mounting and reducing interactions among transducers. A model-based control strategy ensures resonant operation and constant vibration amplitude. Experiments demonstrate levitation forces up to 343 N, with a total levitation height of 25 μm, resulting from two levitation air gaps. Comprehensive performance characterization validates the feasibility of this transducer design for integration into the proposed positioning system.