The Magnetic Levitation Motion Platform Control System

Magnetic suspension has been paid more and more attention because of its many merits such as no mechanical contact, no wear, low power loss, no need of lubrication and long service life, etc. The magnetic plate has various coupling and non-linear characteristics, its bearing characteristic is determined mainly by its configuration parameter and control system. Therefore, it has great significance to research the coupling and bearing characteristic, controller system of the magnetic plate system.The five free-degree dynamic model is set up by Lagrange equation. The coupling characteristic, model error and bearing characteristic are analyzed. Then two control methods, which are discrete control and centralized control, are used to make the plate suspend stably in this paper.First, the coupled electromechanical dynamic model based on PID controller is set up completely. By analyzing the stability of the magnetic plate, the range of the controlling parameters K_p,K_i,K_d is found when the magnetic plate is suspending stably. Through analyzing the relation between the controlling parameters and the stiffness, damping of the magnetic plate system, the controlling parameters are determined finally. Then a fuzzy-PID controller which has better robustness is designed combining the merit of the fuzzy controller. Emulation results indicate that the discrete control based on the fuzzy-PID can make the magnetic plate suspend stably, but the dynamic characteristics is not very good.Two decoupling centralized controller, which are linear state feedback decouple controller and matrix transformation decouple controller, are adopted against the strong coupling characteristic of the magnetic suspension system. Emulation results indicate that the magnetic plate can suspend stably and has better dynamic and static characteristics. But there are many problems such as large real-time calculation, the complexity of controller design, excessive dependence on the precision of mathematical model when the linear state feedback decouple controller is used. The matrix transformation decouple controller is easy to design and utility.At last, the paper presents an application of fuzzy-PID controller design to a magnetic bearing system. The experiment results show that fuzzy-PID control can levitate the suspension system stably and is very robust.