Magnetically Levitated Rotary Table With Six Degrees of Freedom

This paper presents a six-degree-of-freedom magnetically levitated rotary table for fine positioning. The table utilizes a moving magnet motor configuration with the Halbach arrays mounted around the perimeter of the table. The actuation forces are achieved by using the Lorentz force, where the coils are made using printed circuit board technology. By using four three-phase amplifiers, a total of eight independently controlled forces are produced. Closed-loop motion control is achieved by using four optical encoders and four capacitive sensors. Movement is unlimited rotating around the Z-axis and limited in the additional three linear (X , Y, Z) axes and two rotary axes around X and Y , respectively. The table has been manufactured and experimentally demonstrated to deliver submicrometer accuracy in precision micromachining application.