Passive Limitations for a Magnetic Gravity Compensator

Abstract

The development of sophisticated advanced vibration isolation is important because 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. 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 are presented and consequently are used to illustrate the feasibility of using passive permanent magnets for gravity compensation in this demanding high precision industrial application.

Three-Dimensional Analytical Calculation of the Torque Between Permanent Magnets in Magnetic Bearings

“…2, have distinct features such as clean, noiseless, and vibration and maintenance free, although high costs due to control apparatus prevent their wide applications at present [1]. However, due to their inherently high control bandwidth and accuracy they are under focus for high-performance bearing applications [2]- [5]. Accurate modeling tools are essential to obtain designs suitable to facilitate the ever growing demands.…”

Three-Dimensional Analytical Field Calculation of Pyramidal-Frustum Shaped Permanent Magnets

“…ERMANENT MAGNET (PM)-based gravity compensation is a relatively new but increasingly used technique in vibration isolation devices [1]- [3]. Conventional techniques, such as hydraulic or air-based gravity compensators, generally exhibit higher force density and are technically more mature compared to PM based devices.…”

“…It is shown in [3] that the PM topology of a gravity compensator is of significant influence on the produced force. More specifically, topologies which focus the magnetic flux to a small volume, such as the Halbach topology, provide the highest force density.…”

“…More specifically, topologies which focus the magnetic flux to a small volume, such as the Halbach topology, provide the highest force density. In [3], solely cuboidal PMs are used to investigate the achievable force density for bidirectional (or checkerboard) arrays and Halbach arrays. Increased flux focusing properties, hence, increased force density, may be achieved by means of differently shaped PMs, such as the 3D trapezoidal magnets in this paper.…”

Analytical Force, Stiffness, and Resonance Frequency Calculations of a Magnetic Vibration Isolator for a Microbalance

“…In the last few years, research has been conducted on permanent-magnet-based levitation and isolation systems, e.g., in combination with mechanical [2]- [4] or fully magnetic [5]- [7] means, and in [8], the effects of errors in the magnetization direction on permanent-magnet-based systems are discussed. Such systems can be characterized by three important characteristics, i.e., force, stiffness, and resonance frequency.…”