Transportation of hard disk media using electrostatic levitation and tilt control

Abstract

In electrostatic levitation systems, thin flat objects, such as silicon wafers, can be levitated by controlling the electric field between object and an electrode pattern, depending on the measured gap between them. This allows to manipulate these objects without making physical contact. As the gap between object and electrodes is actively controlled, the system is fairly robust for accelerations perpendicular to the objects surface. However, the restoring force for any lateral disturbance is much lower, as it is not actively controlled. This restricts the allowable lateral accelerations and poses a serious limitation on practical implementation of electrostatic levitation system as a good non-contact object handler. In this paper, the allowable lateral accelerations are increased by tilting the electrodes and object during lateral acceleration. Experimental results show how with tilting control, a levitated aluminium disk always remains aligned with the electrodes, while without tilt control it oscillates around the central point.