A Novel Actuator Based on Near-Field Acoustic Levitation and Electromagnetic Actuation

Electromagnetic actuators based on levitation are widely employed for precision applications because of their extremely high positioning resolution. While the majority of these actuators require measurement and control systems for stabilizing the levitating platform, a few of hybrid actuators function without them, leading to a more compact system. These hybrid electromagnetic actuators usually employ an additional diamagnetic force to achieve stable levitation. However, the payload carrying capacity and bandwidth of these hybrid actuators are limited because of the small magnitude of the diamagnetic force and diamagnetic stiffness respectively. Here we propose a novel hybrid actuator that employs acoustic forces instead of diamagnetic forces to achieve stable levitation. In particular near field acoustic levitation technique was employed to levitate a magnetic stage. The position of the levitating magnetic stage is controlled through electromagnetic forces generated by current-carrying wires developed on a printed circuit board. A mathematical model of the actuator was developed to show that its payload carrying capacity and bandwidth is significantly higher than the diamagnetic levitation based electromagnetic actuators. Finally, the actuator is developed and experiments were performed to demonstrate large payload carrying capacity and the positioning bandwidth in agreement with the mathematical model.