Two-Phase Lorentz Coils and Linear Halbach Array for Multiaxis Precision-Positioning Stages With Magnetic Levitation

• Published in: IEEE/ASME transactions on mechatronics Vol. 22; no. 6; pp. 2662 - 2672
• Main Authors: Nguyen, Vu Huy, Kim, Won-jong
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-12-2017; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Coiling; Coils; Force control; Interferometer stages; Interferometers; Interferometry; Magnetic cores; Magnetic flux; Magnetic levitation; Magnetic levitation vehicles; Magnetic separation; Mathematical analysis; Matrix methods; Motion control; Multiaxis; Nanopositioning; Permanent magnets; permanent-magnet (PM) linear motors; Superconducting magnets; Translational motion; Translations
• ISSN: 1083-4435; 1941-014X
• DOI: 10.1109/TMECH.2017.2769160

In this paper, a new framework for linear permanent-magnet (PM) machines with applications in precision motion control is proposed and validated. A single forcer generating two independent force components in two perpendicular directions is the fundamental unit of the framework. Each forcer consists of two planar Lorentz coils separated by a 90° or 270° phase difference and parallel to a Halbach magnet array. Many coil pairs can be assembled to the same platen to move over a common magnet matrix, forming a linear or planar PM motor. Advantages of this framework include a linear system model, the capability to magnetically levitate the mover in multiaxis stages, and that to generate long translational motion range. The framework developed herein is validated by a six-degree-of-freedom magnetically levitated (maglev) stage. The dimension of the moving platen's frame is 14.3 cm × 14.3 cm, and its total mass is 0.75 kg. The achieved positioning resolution in translations along X, Y , and Z is 10 nm. The positioning resolution in out-of-plane rotation is 0.1 μrad, which is a record in the literature. The maximum travel range in XY with laser interferometers is 56 mm × 35 mm, limited by the size of the precision mirrors. With the coils' total mass of only 0.205 kg, the achieved acceleration is 1.2 m/s 2 . Experimental results exhibit reduced perturbations in other axes of in-plane motions.