Passive Magnetic Suspension Limitations for Gravity Compensation

The development of sophisticated advanced vibration isolation is important, since even the minutest vibrations have disastrous effects on the performance of static and moving parts in high-precision machines. This paper concerns with the isolation of these vibrations for a large static body in an advanced micro-lithographic system, where a passive/active electromagnetic solution is presented. In these configurations passive permanent magnets (PM) provide the gravity compensation and active electromagnets the accurate positioning. However, this paper only considers the applicability of a passive magnetic solution for this high force gravity compensation application, or, more specifically, the influence of various PM array topologies on the force density. Further, fast-solving analytical models will be presented and will consequently be used to illustrate the feasibility of using passive permanent magnets for gravity compensation in this demanding high precision industrial application.