Design of a bidirectional actuator for a nanopositioning system with a permanent magnet and an electromagnet

Abstract

A precision bidirectional linear actuator for ultraprecision systems is proposed and designed in this article. The actuator is composed of a symmetric structure with a force generation unit and a guide mechanism. The force generation part consists of a permanent magnet and an electromagnet, which generate a permanent and a reversible flux, respectively. The combination of permanent and reversible fluxes makes various flux densities in its air gaps between the moving part and the fixed yokes. The difference between flux densities in the lower and upper gaps creates forces for bidirectional linear motions of hundreds of micrometers. As a guide mechanism, two circular plates and one shaft are used. Reducing other forces generated by motions, except the z-directional motion, these circular plates in the form of a flexure endow the actuator with smooth motion, freedom from wear, and a high stiffness for a rapid settling time. The function of the shaft is to transfer motion to an object. Finally, the total body has a symmetric structure enabling it to be stable in terms of thermal error. The actuator is designed with the software tools MAXWELL ™ 2D and PRO-MECHANICA ™. The designed actuator is evaluated with a linear current amplifier, a laser Doppler vibrometer for nanometer resolution, a dynamic signal analyzer for frequency responses of the proposed actuator, and a simple proportional-integral-derivative controller for its tracking performance.

Robust design of a novel three-axis fine stage for precision positioning in lithography

“…They also consider the permeance of leakage flux from the magnets and yoke. All the magnets are assumed as flux sources with permeance P m and source flux r [7,8]. To improve the design, several constraints such as size limitation, heat generation, Table 4.…”

Design parameter study of a permanent magnet biased magnetic actuator for improving stiffness and linearity

“…The PM-biased MA is mainly applied to a radial bearing for high speed rotors (Murphy et al, 2004;Meeks et al, 1994), and is occasionally combined with an axial bearing (McMullen et al, 2000). It is often used as an actuator for precision positioning (Molenaar et al, 1997;Lee et al, 2002;Kim and Gweon, 2005), and as a vibration isolator (Lee and Lee, 2006) or electro-magnetic exciter (Lequesne, 1990;Oberbeck and Ulbrich, 2002).…”

“…: +82 2 883 1513 E-mail address:dchan@snu.ac.kr operation range than the conventional electromagnetic actuator. Figure I shows the I-OaF PM-biased MA (Lee et al, 2002;Kim and Gweon, 2005) consists of a center core wound by serially connected upper and lower coils and two side core connected to centers core by PMs. In the concept of the PM-biased MA, the electromagnet flux does not pass through the PM, and the total air gap in the EM flux path is constant.…”

“…To date, the full 2002; Kim and Gweon, 2005) used for the dimensional analysis. It is composed of an assembled moving part of cores, two PMs and serially-connected coils between the upper and lower fixed guides.…”

A novel bidirectional and dual-redundancy hybrid electromagnetic brake for aircraft

“…[10][11][12] In addition, the currently widely used unidirectional electromagnet cannot satisfy the multifunction requirements. The existing bidirectional hybrid electromagnets are often used for precision manufacturing and measuring system [13][14][15][16] and not for highpower equipment.…”