Design and Experiment of a Macro-Micro Planar Maglev Positioning System

In this paper, a new planar magnetic levitation (maglev) positioning system is proposed, which is capable of executing dual-axis planar motions purely involving magnetic forces. Functionally, such a mechanism behaves like a planar XY table with micrometer precision. Specifically, in this system, a new structure with an adaptive sliding-mode control (ASMC) algorithm is described, which aims to achieve the following three goals: 1) a large moving range (millimeter level); 2) precise positioning (micrometer level); and 3) fast response. The system consists of a moving carrier platform, six permanent magnets (PMs) attached to the carrier, and six electromagnets mounted on a fixed base. After exploring the characteristics of the magnetic forces between PMs and electromagnets, the general 6-DOF dynamic model of this system is derived and analyzed. Then, because of the naturally unstable behavior inherent in maglev systems, the proposed ASMC guarantees satisfactory performance of the maglev system. Experiments have successfully demonstrated the feasibility and effectiveness of the overall system.