Design and Implementation of an New 6-DoF Magnetic Levitation Positioning System

Abstract

High-precision magnetic levitation positioning systems are of great interest for many modern applications, because of their absolutely non-contact operation and large planar travel ranges with precisions up to the nanometer range. In this article, a novel six degrees-of-freedom (6-DoF) magnetic levitation (maglev) system, which is based on repulsive levitation forces, is presented. Compared to other known solutions from the literature, this proposed concept allows a freely accessible mover from above in combination with decoupled levitation and propulsion forces. The maglev system consists of eight air-core coils in order to realize a 6-DoF motion. The six-axes position measurement is achieved by four eddy current sensors and four optical laser sensors. After a detailed explanation of the working principle, a decoupled 6-DoF dynamic model is derived and analyzed. Then, based on this dynamic model, simple proportional–integral–differential (PID) controllers are implemented in order to control the unstable behavior of the system. The aim of this article is to demonstrate the functionality of the proposed system. Thus, various experimental results, obtained from the prototype, were conducted to evaluate the dynamic performance of the maglev system. It will be shown that the position errors lie in the range of the sensor resolution and, thus, can be made as small as desired, depending on the applied sensor resolution.