Directed-Driven 8-Phase Magnetically Levitated Rotary Table Based on an Analytical-Numerical Model

Abstract

The magnetically levitated rotary table (MLRT) has the potential to be applied in many industrial applications due to its excellent rotation ability and good positioning accuracy. This paper presents the prototype of a novel MLRT with a simple and compact structure. The table employs a circular permanent magnet (PM) array and a circular coil array to generate large scale rotation around the vertical axis and limited movement in the other directions. This MLRT has a higher current carrying capacity and simpler commutation law than the existing MLRT. Furthermore, different from the previous works, the magnetic force model presented in this paper is obtained by a novel analytical-numerical method that considers the clearances in the circular PM array. Thus, the predicted magnetic force and torque are more accurate than those from the existing modeling method. The translation and rotation of the table are measured by six laser sensors, which are distributed around and below the mover respectively. The PID controller is used to stabilize the system. Experiments related to the motion decoupling, trajectory tracking and load change are carried out to verify the motion performance of the novel rotary table. Compared with the existing magnetic force model, the experimental results illustrate that the novel magnetic force model, which considers the clearances in a circular PM array, is more suitable for motion control of the MLRT.

Keywords

• Magnetically levitated rotary table (MLRT)
• circular permanent magnet (PM) array
• magnetic force model
• motion control