Multiple Magnetic Suspension System

(16th report : Basic Characteristics of Two-degree-of-freedom Motions Control Using Parallel Magnetic Suspension)

Abstract

Parallel magnetic suspension that controls multiple floators or multi-degree-of-freedom motions with a single power amplifier has already been realized. In this system, all of the suspended points move simultaneously even when a disturbance acts on one of the suspended points solely because all electromagnet’s coils are connected. This paper studies the moving direction of each suspended point with respect to a step disturbance in double parallel magnetic suspension system. The analytical study shows that the response direction is determined by the system parameter that relates the response speed of each subsystem. In the slower subsystem, the suspended point moves in the same direction as the applied force while in the faster subsystem, the suspended point moves in the opposite direction. In other words, the slower subsystem has positive stiffness while the faster system has negative stiffness. To confirm this prediction, step responses are measured in the experimental apparatus.