A stator for a self-running, ultrasonically-levitated sliding stage

Here we propose a self-running, ultrasonically-levitated sliding stage and investigate the levitation and propulsion characteristics of its stator. The stator consists of two aluminum beams and four PZT plates, which have two-paired bimorph configurations. A flexural standing wave was generated along the beam by applying an input voltage to the PZTs, and the stator could be levitated from a flat substrate by the acoustic radiation force generated by its own vibrating beam. The size of the stator was optimized using finite-element analysis (FEA) to maximize the vibration displacement amplitude of the beam. The flexuial vibration modes at 24.3 and 102 kHz were the most prominent vibration modes having large displacement amplitudes. The stator was levitated at 23.2 and 96.1 kHz, which are close to the frequencies predicted by the FEA results. A standing wave was observed along the beam. The experimental and the simulated results showed good agreement. The levitation distance h was measured by varying the vibration displacement amplitude of the beam u, and was found to be proportional to u. When a traveling wave was excited along the beam by controlling the temporal phase difference of the two transducers, the stator could be made to hover and to move in the opposite direction to the traveling wave. The stator moved in the positive direction when the phase difference was in the ranges 0° to 200° and 310° to 360°, and in the negative direction when the phase difference was between 220° and 260°.