Abstract
The author has been active in the development of levitation devices for precision positioning during the last 18 years. Principal among the techniques studied has been the use of two-force or levitation linear motors. These motors have been designed into stages for precision positioning in lithography, scanned probe microscopy, and other precision measurement systems. In such devices, the use of levitation linear motors allows the control of six stage degrees of freedom to nanometer resolution with a single moving part.
This paper presents an overview of the operating principles, electromagnetic configurations, and system level performance of levitation linear motors for precision applications. The configuration of such motors is most commonly an iron-free permanent magnet array in the Halbach configuration which is driven by an iron-free multiphase coil set. By properly choosing the phase drive currents, forces in levitation and translation can be controlled. This opens possibilities for novel positioning system configurations and performance capabilities.
